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tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 1 copyrigh t ? 2005, trinamic motion control gmbh & co kg trinamic ? motion control gmbh & co kg sternstra?e 67 d C 20357 hamburg germany www.trinamic.com features the tmc249 / tmc249a (1) is a dual full bridge driver ic for bipolar stepper motor control applications. the tmc249 is realized in a hvcmos technology and directly drives eight external low - rds - on high efficiency mosfets. it supports more than 6000ma coil current. the low power dissipation makes the tmc249 an optimum choice for drives, where a high reliabili ty is desired. with additional drivers, motor current and voltage can be increased. the integrated unique sensorles s stall detection (pat. pend.) s tallguard? makes it a good choice for applications, where a reference point is needed, but where a switch is not desired. its ability to predict an overload makes the tmc249 an optimum choice for drives, where a high reliability is desired. internal dacs allow microstepping as well as smart current control. the device can be controlled by a serial interface (spi? i ) or by analog / digital input signals. short circuit, temperature, undervoltage and overvoltage protection are integrated. more than 6000ma using 8 external mos transistors (e.g. 4a rms) sensorless stall detection s tallguard ? and load measurement integra ted control via spi with easy - to - use 12 bit protocol or external analog / digital signals short circuit, overvoltage and over temperature protection integrated status flags for overcurrent, open load, over temperature, temperature pre - warning, undervoltage integrated 4 bit dacs allow up to 16 times microstepping via spi, any resolution via analog control (for up to 64 microsteps via spi see last manual page) mixed decay feature for smooth motor operation slope control user programmable to reduce electromagne tic emissions chopper frequency programmable via a single capacitor or external clock current control allows cool motor and driver operation 7v to 34v motor supply voltage (a - type) up to 58v motor supply voltage using a few additional low cost components 3 .3v or 5v operation for digital part low power dissipation via low rds - on power stage standby and shutdown mode available choice of so28 or chip size mlf package (1) the term tmc249 in this datasheet always refers to the tmc249a and the tmc249. the major diff erences in the older tmc249 are explicitly marked with non - a - type. the tmc249a brings a number of enhancements and is fully backward compatible to the tmc249. tmc249/a C data sheet high current microstep stepper motor driver with stallguard?, protection / diagnostics and spi interface
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 2 copyrigh t ? 2005, trinamic motion control gmbh & co kg features ................................ ................................ ................................ ................................ ............. 1 pinning ................................ ................................ ................................ ................................ .................. 5 p ackage codes ................................ ................................ ................................ ................................ ... 5 so28 d imensions ................................ ................................ ................................ ................................ 6 qfn32 d imensions ................................ ................................ ................................ .............................. 6 application circuit / block diagram ................................ ................................ ....................... 7 p in f unctions ................................ ................................ ................................ ................................ ...... 7 selecting power tran sistors ................................ ................................ ................................ ... 8 l ist of recommended t ransistors ................................ ................................ ................................ .... 8 layout consideration s ................................ ................................ ................................ ................ 9 using additional pow er drivers ................................ ................................ ............................. 10 control via the spi interface ................................ ................................ ................................ . 11 s erial data word tran smitted to tmc249 ................................ ................................ ..................... 11 s erial data word tran smitted from tmc249 ................................ ................................ ................ 11 t ypical motor coil current values ................................ ................................ ................................ 12 b ase current control via ina and inb in spi mode ................................ ................................ ....... 12 c ontrolling the power down mode via the spi interface ................................ ........................... 12 o pen load detection ................................ ................................ ................................ ........................ 13 s tandby and shutdown mode ................................ ................................ ................................ .......... 13 p ower saving ................................ ................................ ................................ ................................ .... 13 stall detection stal lguard? ................................ ................................ ................................ 14 u sing the sensorless load measurement ................................ ................................ ...................... 14 i mplementing sensorle ss stall detection ................................ ................................ ..................... 14 protection functions ................................ ................................ ................................ ................. 15 o vercurrent protectio n an d diagnosis ................................ ................................ ........................ 15 o ver temperature prot ection and diagnosis ................................ ................................ ................ 15 o vervoltage protectio n and enn pin behavior ................................ ................................ ............ 15 chopper p rinciple ................................ ................................ ................................ ......................... 16 c hopper cycle / u sing the mixed decay feature ................................ ................................ ........... 16 a dapting the sine wav e for smooth motor o peration ................................ ................................ .. 17 b la nk t ime ................................ ................................ ................................ ................................ ......... 17 b lank time settings ................................ ................................ ................................ .......................... 17 classical non - spi control mode (st and alone mode) ................................ .................. 18 p in functions in stan d alone mode ................................ ................................ ................................ . 18 i nput signals for mic rostep control in st and alone mode ................................ .......................... 18 unipolar operation ................................ ................................ ................................ ...................... 19 d ifferences of short circuit behavior in unipolar ope ration mode ................................ ........... 19 d ifferences in choppe r cycle in unipolar operation mode ................................ .......................... 19 calculation of the e xternal components ................................ ................................ ....... 20 s ense r esistor ................................ ................................ ................................ ................................ . 20 e xamples for sense re sistor settings ................................ ................................ .......................... 20 h igh side overcurrent detection resistor r sh ................................ ................................ ............ 20 m aking th e circuit short circ uit proof ................................ ................................ ......................... 21 o scillator c apacitor ................................ ................................ ................................ ...................... 22 t able of oscillator f requencies ................................ ................................ ................................ ... 22 p ull - up resistors on unus ed inputs ................................ ................................ ............................... 22 p ower supply sequenci ng considerations ................................ ................................ .................... 22
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 3 copyrigh t ? 2005, trinamic motion control gmbh & co kg s lope c ontrol r esistor ................................ ................................ ................................ ................. 23 absolute maximum rat ings ................................ ................................ ................................ ....... 24 electrical character istics ................................ ................................ ................................ ..... 24 o perational r ange ................................ ................................ ................................ .......................... 24 dc c haracteristics ................................ ................................ ................................ ......................... 25 ac c haracteristics ................................ ................................ ................................ ......................... 27 t hermal p rotection ................................ ................................ ................................ ......................... 27 spi interface timing ................................ ................................ ................................ ...................... 28 p ropagation t imes ................................ ................................ ................................ ........................... 28 u sing the spi interface ................................ ................................ ................................ ................... 28 spi f ilter ................................ ................................ ................................ ................................ .......... 28 application note: ex tending the microste p resolution ................................ ............. 29 d ocumentation revisio n ................................ ................................ ................................ ............ 30
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 4 copyrigh t ? 2005, trinamic motion control gmbh & co kg life suppor t policy trinamic motion control gmbh & co kg does not authorize or warrant any of its products for use in life support systems, without the specific written consent of trinamic motion control gmbh & co kg. life support systems are equipment intended to support or sustain life, and whose failure to perform, when properly used in accordance with instructions provided, can be reasonably expected to result in personal injury or death. ? trinamic motion control gmbh & c o kg 2005 information given in this data sheet is believed to be accurate and reliable. however no responsibility is assumed for the consequences of its use nor for any infringement of patents or other rights of third parties, which may result from its us e. specifications subject to change without notice.
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 5 copyrigh t ? 2005, trinamic motion control gmbh & co kg pinning note: cooling plane on - la type should be connect ed to gnd or left open. package codes type package temperature range lead free code/marking tmc249a so28 automotive (1) yes tmc249a - sa tmc249 so28 automotive (1) from date code 05 05 (wwyy) tmc249 - sa tmc249a qfn32, 7*7mm until date code 1808 automotiv e (1) yes tmc249a - la / 249a - la (1) ics are not tested according to automotive standards, but are usable within the complete automotive temperature range. tmc249 / 249a so28 1 2 3 4 5 6 7 28 27 26 25 24 23 22 17 sdo sdi la2 ha1 inb ha2 sra la1 agnd ann slp ina 16 bl2 sck 15 lb1 8 9 10 11 12 13 14 srb csn hb1 bl1 osc lb2 20 gnd 19 vs 18 vt 21 vcc hb2 enn spe agnd ann ha1 ha2 - sra inb vs enn csn sdi sck srb lb2 lb1 - hb2 hb1 bl2 vt bl1 top view la1 la2 32 31 30 29 28 27 26 25 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 tmc 249-la spe sdo osc gnd gnd vcc ina - slp
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 6 copyrigh t ? 2005, trinamic motion control gmbh & co kg so28 dimensions ref min max a 10 10.65 b 17.7 18.1 c 7.4 7.6 d 1.4 e 2.65 f 0.25 g 0.1 0.3 h 0.36 0.49 i 0.4 1.1 k 1.27 all dimensions are in mm. qfn32 dimensions ref min nom max a 0.80 0.90 1.00 a1 0.00 0.02 0.05 a3 0.20 l1 0.03 0.15 d 7.0 e 7.0 d2 5.00 5.15 5.25 e2 5.00 5.15 5.25 l 0.45 0.55 0.65 b 0.25 0.30 0.35 e 0.6 5 all dimensions are in mm. attention: drawing not to scale. i e f c a k h b d g -c- a 3 a 1 side view plane a ccc c 0.08 c nx seating d d/2 index area e a a a c aaa c top view 2x 2 x (d/2 xe/2) e / 2 -b- - a - n x l e nxb d2/2 d2 e 2 / 2 2 1 e 2 bbb c a b ddd c -b- - a - n n-1 btm view 6 5 (d/2 xe/2) index area see detail b see detail b bottom view with type c id n-1 1 2 n radius datum a or b detail b terminal tip e e/2 l 1
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 7 copyrigh t ? 2005, trinamic motion control gmbh & co kg application circuit / block diagram pin functions pin fu nction pin function vs motor supply voltage vt short to gnd detection comparator C connect to vs if not used vcc 3.0 - 5.5v supply voltage for analog and logic circuits gnd digital / power ground agnd analog ground (reference for sra, srb, osc, slp, ina, inb, slp) osc oscillator capacitor or external clock input for chopper ina analog current control phase a inb analog current control input phase b sck clock input of serial interface sdo data output of serial interface (tri - state) sdi data input of seri al interface csn chip select input of serial interface enn device enable (low active), and overvoltage shutdown input spe enable spi mode (high active). tie to gnd for non - spi applications ann enable analog current control via ina and inb (low active) sl p slope control re sistor. tie to gnd for fastest slope bl1, bl2 digital blank time select sra, srb bridge a/b current sense resistor input ha1, ha2, hb1, hb2 outputs for high side p - channel transistors la1, la2, lb1, lb2 outputs for low side n - channel t ransistors r s r sh coil a +v m r s coil b 100f 220nf n n n n p p p p tmc249 ha1 ha2 la2 la1 lb1 lb2 hb2 hb1 srb sra vt vs 4 dac 4 dac ina inb vref refsel pwm-ctrl ann spe 1 0 0 1 current controlled gate drivers current controlled gate drivers slp r slp pwm-ctrl osc control & diagnosis parallel control spi- interface refsel gnd agnd under- voltage tem- perature osc vcc 1nf 100nf +v cc sck sdi sdo csn bl2 bl1 [mdbn] [pha] [err] [phb] stand alone mode [mdan] [...]: function in stand alone mode enn vcc/2 load mesure- ment
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 8 copyrigh t ? 2005, trinamic motion control gmbh & co kg selecting power transistors selection of power transistors for the tmc249 depends on required current, voltage and thermal conditions. driving large transistors directly with the tmc249 is limited by the gate capacity of these transistors. if the total gate charge is too high, slope time increases and leads to a higher switching power dissipation. a total gate charge of maximum 25nc per transistor pair (n gate charge + p gate charge) is recommended (at 25nc, tie pin slp to gnd to get an accepta ble slope). the table below shows a choice of transistors which can be driven directly by the tmc249. the maximum application current mainly is a function of cooling and environment temperature. rdson and gate charge are read at the nominal drive voltage o f 6v and 25c. all of these transistor types are mainly cooled via their drain connections. in order to provide sufficient cooling, the transistors should be directly connected to massive traces on the pcb which are widened near the transistor package, pr oviding a copper area of some square cm. the heat then is dissipated vertically through the pcb to a massive power or ground plane, which shall cover most of the pcb area in order to use the whole pcb for cooling. as an example, the minimum pcb size requir ed to reach the given current for the si7501, is about 42mm * 42mm, yielding in a heat up of the transistor packages of about 85c above ambient temperature. with a 100mm * 100mm pcb, this reduced to 70c above ambient temperature, so that safe operation i s possible up to 60c ambient temperature at maximum current (transistor package at 130c). list of recommended transistors manu facturer and type package (#trans) max. appli - cation voltage rds on [ohm] total gate charge [nc] typical maximum appli cation current remark fairchild semi fdd 8424 h to252 - 4 (1n,1p) 34v 0.023 0.045 10 10 6000ma (1) (2) siliconix si 7501 dn ppack (1n,1p) 28.5v 0.035 0.055 5.5 8.0 4200ma (1) trinamic tmc34np ppack (1n,1p) 28.5v 0.035 0.055 5.5 8.0 4200ma (1) fairchild sem i fds 8960 so8 (1n,1p) 34v 0.023 0.050 7.0 7.0 4000ma (1) (2) fairchild semi fds 8958 a so8 (1n,1p) 28.5v 0.023 0.050 7.0 7.0 4000ma (2) siliconix si 4539 ady so8 (1n,1p) 28.5v 0.040 0.060 7.5 9.0 3500ma siliconix si 4532 ady so8 (1n,1p) 28.5v 0.055 0 .080 4.5 6.5 3000ma 5000ma (2 parallel) (3) fairchild semi fds 8333c so8 (1n,1p) 28.5v 0.075 0.130 2.9 3.0 2800ma 5000ma (2 parallel) (3) irf 9952 (/ irf 7509) so8 (1n,1p) 28.5v 0.075 0.280 4.5 4.0 2500ma trinamic tmc32np - mlp mlp (1n,1p) 28.5v 0.120 0.250 2.8 2.5 2300ma 4400ma (2 parallel) very small! (3) siliconix si 5504 1206 - 8 (1n,1p) 28.5v 0.090 0.170 3.0 3.2 2000ma very small! trinamic tmc32np2 - sm8 sm8 (2n,2p) 28.5v 0.120 0.250 2.8 2.5 2000ma only 2 packages! siliconix si 4559 ey so8 (1n,1 p) 34v or 58v (see a/n) 0.045 0.120 11 10 3000ma 2500ma (at 48v) (4) (1) these p - channel transistors have a very high drain to gate capacity, which may introduce destructive current impulses into the ha/hb outputs by forcing them above the power supply leve l, depending on the low - side slope. to ensure reliability, connect one mss1p3 or zhcs1000 or an ss14 1a schottky diode or similar to both ha and hb outputs against vs to protect them. (2) compare (1), but for n - channel transistor. protect la/lb outputs with on e schottky diode to gnd. (3) higher current with two devices in parallel, i.e. using 8 double transistors instead of four. (4) see application note document for simple extension to operate at up to 58v.
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 9 copyrigh t ? 2005, trinamic motion control gmbh & co kg layout considerations for optimal operation of the circuit a careful board layout is important, because of the combination of high current chopper operation coupled with high accuracy threshold comparators. please pay special attention to massive grounding. depending on the required motor current, either a single massive ground plane or a ground plane plus star connection of the power traces may be used. the schematic shows how the high current paths can be routed separately, so that the chopper current does not flow through the systems gnd - plane. tie the tmc249s agnd and gnd to the gnd plane. additionally, use enough filtering capacitors located near to the boards power supply input and small ceramic capacitors near to the power supply connections of the tmc249. use low inductance sense resistors, or add a ceram ic capacitor in parallel to each resistor to avoid high voltage spikes. in some applications it may become necessary to introduce additional rc - filtering into the sra / srb line, as shown in the schematic, to prevent spikes from triggering the short circui t protection or the chopper comparator . alternatively , a 470nf ceramic capacitor can be placed across the sense resistors . if you want to take advantage of the thermal protection and diagnosis, ensure, that the power transistors are very close to the packa ge, and that there is a good thermal contact between the tmc249 and the external transistors. please be aware, that long or thin traces to the sense resistors may add substantial resistance and thus reduce output current. the same is valid for the high sid e shunt resistor. place the optional shunt resistor voltage divider near the tmc249, in order to avoid voltage drop in the vcc plane to add up to the measured voltage. +vm gnd gnd- plane r sb r sa bridge a bridge b r sh c vm 100r optional voltage divider vs vt tmc249/ tmc239a 100r 100r 3.3 - 10nf sra srb optional filter agnd gnd 100nf r div
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 10 copyrigh t ? 2005, trinamic motion control gmbh & co kg using additional power drivers for higher voltage and higher output current it is poss ible to add external mosfet gate drivers. both, dedicated transistor drivers are suitable, as well as a circuit based on standard hcmos drivers. it is important to understand the function of dedicated gate drivers for n - channel transistors: since the chopp ing also can be stopped in open load conditions, the gate drive circuit for the upper transistors should allow for continuous on conditions. in the schematic below this is satisfied by attaching a weak additional charge pump oscillator and pumping the vs u p to the high voltage supply. do not enable the tmc249, before the gate driver capacitors are charged to an appropriate voltage. a current sensing comparator in the vm line pulling down the vt pin by some 100mv on overcurrent can be added, if required. sin ce the tmc249 in this application can not sense switch - off of the transistor gates to ensure break - before - make operation, the break before - make - delays have to be set by capacitive loading of its transistor drive outputs. the capacitors cdhs and cdls are ch arged / discharged with the nominal gate current. the opposite output is not enabled, before the switching - off output has been discharged to 0.5v. to calculate the timing, refer to the required logic levels of the attached power driver, resp. the attached pmos. for cdhs and cdls 470pf give about 100ns. both circuits do not show decoupling capacitors and further details. high current, high voltage mos, e.g. si4450 r s coil n n ha1 la1 sra vt tmc249/ tmc239 vs small signal p- mos, e.g. bss84 +12v ls- driver +v m e.g. 50v hs-driver 1f c dhs 470p c dls 470p 2n2 c-pump 20khz icm7555 to other bridges 100r 4.7nf opt. 22k n n ir2101 12v 390r 390r 1k slp 10k set hs and ls current to 10ma 1k high voltage logic level mos bridge r s coil n n p p ha1 la1 sra vt tmc249/ tmc239 vs +v s +v m 20..60v c dhs c dls 1k 1/2 74hc244 on low side +5v 1k 1/2 74hc244 on high side vm-5.2v 1k slp 15k set to 7 ma high- side drive current lm337 hv 120r 390r adj out in 55v low current n-mos 7..15v 100r 100r gnd vcc vcc gnd /oe /oe
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 11 copyrigh t ? 2005, trinamic motion control gmbh & co kg control via the spi interface the spi data word sets the current and polarity for both coils. by applying consec utive values, describing a sine and a cosine wave, the motor can be driven in microsteps. every microstep is initiated by its own telegram. please refer to the description of the analog mode for details on the waveforms required. the spi interface timing i s described in the timing section. we recommend the tmc428 to automatically generate the required telegrams and motor ramps for up to three motors. serial data word transmitted to tmc249 (msb transmitted first) bit name function remark 11 mda mixed deca y enable phase a 1 = mixed decay 0 = current flow from oa1 to oa2 1 = mixe 0 = current flow from ob1 to ob2 serial data word transmitted from tmc249 (msb transmitted first) bit name function remark 11 ld2 load indicator bit 2 msb 10 ld1 load indicator bit 1 9 ld0 load indicator bit 0 lsb 8 1 always 1 1 = chip off due to overtemperature 1 = prewarning temperature exc 1 = undervoltage on vs
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 12 copyrigh t ? 2005, trinamic motion control gmbh & co kg typical motor coil current values current setting ca3.. 0 / cb3..0 percentage of current typical trip voltage of the current sense comparator (internal reference or analog input voltage of 2v is used) 0000 0% 0 v (bridge continuously in slow decay condition) 0001 6.7% 23 mv 0010 13.3% 45 mv ... ... 1110 93.3% 317 mv 1111 100% 340 mv the current values correspond to a standard 4 bit dac, where 100%=15/16. the contents of all registers is cleared to 0 on power - on reset or disable via the enn pin, bringing the ic to a low power standby mode. all spi inp uts have schmitt - trigger function. base current control via ina and inb in spi mode in spi mode, the ic can use an external reference voltage for each dac. this allows the adaptation to different motors. this mode is enabled by tying pin ann to gnd. a 2.0 v input voltage gives full scale current of 100%. in this case, the typical trip voltage of the current sense comparator is determined by the input voltage and the dac current setting (see table above) as follows: v trip,a = 0.17 v ina percentage spi cur rent setting a v trip,b = 0.17 v inb percentage spi current setting b a maximum of 3.0v v in is possible. multiply the percentage of base current setting and the dac table to get the overall coil current. it is advised to operate at a high base current setting, to reduce the effects of noise voltages. this feature allows a high resolution setting of the required motor current using an external dac or pwm - dac (see schematic for examples). controlling the power down mode via the spi interface programming current value 0000 for both coils at a time clears the overcurrent flags and switches the tmc249 into a low current standby mode with coils switched off. 47k 100nf agnd ina inb ann c- pwm using pwm signal 100k c- port .2 8 level via r2r-dac 51k 51k 51k 100k 100k c- port .1 c- port .0 r1 2 level control r2 c- port +v cc 10nf standard function 11 mxa 10 ca3 9 ca2 6 pha - 0 - control word function - - bit enable standby mode and clear error flags 8 ca1 7 ca0 5 mxb 4 cb3 3 cb2 0 phb 2 cb1 1 cb0 0 0 0 0 0 0 0
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 13 copyrigh t ? 2005, trinamic motion control gmbh & co kg open load detection open load is signaled, whenever there are more than 14 oscill ator cycles without pwm switch off. note that open load detection is not possible while coil current is set to 0000, because the chopper is off in this condition. the open load flag will then always be read as inactive (0). during overcurrent and under voltage or over temperature conditions, the open load flags also become active! due to their principle, the open load flags not only signal an open load condition, but also a torque loss of the motor, especially at high motor velocities. to detect only an interruption of the connection to the motor, it is advised to evaluate the flags during stand still or during low velocities only (e.g. for the first or last steps of a movement). standby and shutdown mode the circuit can be put into a low power standby mode by the user, or, automatically goes to standby on vcc undervoltage conditions. before entering standby mode, the tmc249 switches off all power transistors, and holds their gates in a disable condition using high ohmic resistors. in standby mode the os cillator becomes disabled and the oscillator pin is held at a low state. the standby mode is available via the interface in spi - mode and via the enn pin in non - spi mode. the shutdown mode even reduces supply current further. it can only be entered in spi - mode by pulling the enn pin high. in shutdown additionally all internal reference voltages become switched off and the spi circuit is held in reset. power saving the possibility to control the output current can dramatically save energy, reduce heat gen eration and increase precision by reducing thermal stress on the motor and attached mechanical components. just reduce motor current during stand still: even a slight reduction of the coil currents to 70% of the current of the last step of the movement, ha lves power consumption! in typical applications a 50% current reduction during stand still is reasonable.
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 14 copyrigh t ? 2005, trinamic motion control gmbh & co kg stall detection stallguard ? using the sensorless load measurement the tmc249 provides a patented sensorless load measurement, which allows a digital read out of the mechanical load on the motor via the serial interface. to get a readout value, just drive the motor using sine commutation and mixed decay switched off. the load measurement then is available as a three bit load indicator during normal motion of the m otor. a higher mechanical load on the motor results in a lower readout value. the value is updated once per fullstep. the load detection is based on the motors back emf, thus the level depends on several factors: - motor velocity: a higher velocity leads t o a higher readout value - motor resonance: motor resonances cause a high dynamic load on the motor, and thus measurement may give unsatisfactory results. - motor acceleration: acceleration phases also produce dynamic load on the motor. - mixed decay setting: fo r load measurement mixed decay has to be off for some time before the zero crossing of the coil current. if mixed decay is used, and the mixed decay period is extended towards the zero crossing, the load indicator value decreases. implementing sensorless stall detection the sensorless stall detection typically is used, to detect the reference point without the usage of a switch or photo interrupter. therefore the actuator is driven to a mechanical stop, e.g. one end point in a spindle type actuator. as soo n as the stop is hit, the motor stalls. without stall detection, this would give an audible humming noise and vibrations, which could damage mechanics. to get a reliable stall detection, follow these steps: 1. choose a motor velocity for reference movement. use a medium velocity which is far enough away from mechanical resonance frequencies. in some applications even motor start / stop frequency may be used. with this the motor can stop within one fullstep if a stall is detected. 2. use a sine stepping pattern and switch off mixed decay (at least 1 to 3 microsteps before zero crossing of the wave). monitor the load indicator during movement. it should show a stable readout value in the range 3 to 7 (l move ). if the readout is high (>5), the mixed decay portion ma y be increased, if desired. 3. choose a threshold value l stall between 0 and l move - 1. 4. monitor the load indicator during each reference search movement, as soon as the desired velocity is reached. readout is required at least once per fullstep. if the readou t value at one fullstep is below or equal to l stall , stop the motor. attention: do not read out the value within one chopper period plus 8 microseconds after toggling one of the phase polarities! 5. if the motor stops during normal movement without hitting th e mechanical stop, decrease l stall . if the stall condition is not detected at once, when the motor stalls, increase l stall . v_max t v(t) a_max acceleration constant velocity stall min max t load indicator stall detected! stall threshold vibration acceleration jerk l move l stall
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 15 copyrigh t ? 2005, trinamic motion control gmbh & co kg protection functions overcurrent protection and diagnosis the tmc249 uses the current sense resistors on the low side to detect an overcurrent: whenever a voltage above 0.61v is detected, the pwm cycle is terminated at once and all transistors of the bri dge are switched off for the rest of the pwm cycle. the error counter is increased by one. if the error counter reaches 3, the bridge remains switched off for 63 pwm cycles and the error flag is read as active. the user can clear the error condition in a dvance by clearing the error flag. the error counter is cleared, whenever there are more than 63 pwm cycles without overcurrent. there is one error counter for each of the low side bridges, and one for the high side. the overcurrent detection is inactive d uring the blank pulse time for each bridge, to suppress spikes which can occur during switching. the high side comparator detects a short to gnd or an overcurrent, whenever the voltage between vs and vt becomes higher than 0.15 v at any time, except for the blank time period which is logically ored for both bridges. here all transistors become switched off for the rest of the pwm cycle, because the bridge with the failure is unknown. the overcurrent flags can be cleared by disabling and re - enabling the c hip either via the enn pin or by sending a telegram with both current control words set to 0000. in high side overcurrent conditions the user can determine which bridge sees the overcurrent, by selectively switching on only one of the bridges with each p olarity (therefore the other bridge should remain programmed to 0000). over temperature protection and diagnosis the circuit switches off all output power transistors during an over temperature condition. the over temperature flag should be monitored to d etect this condition. the circuit resumes operation after cool down below the temperature threshold. however, operation near the over temperature threshold should be avoided, if a high lifetime is desired. overvoltage protection and enn pin behavior durin g disable conditions the circuit switches off all output power transistors and goes into a low current shutdown mode. all register contents is cleared to 0, and all status flags are cleared. the circuit in this condition can also stand a higher voltage, because the voltage then is not limited by the maximum power mosfet voltage. the enable pin enn provides a fixed threshold of ? v cc to allow a simple overvoltage protection up to 40v using an external voltage divider (see schematic). enn r2 c-port (opt.) low=enable, high=disable r1 +v m for switch off at 26 - 29v: at vcc=5v: r1=100k; r2=10k at vcc=3.3v: r1=160k; r2=10k
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 16 copyrigh t ? 2005, trinamic motion control gmbh & co kg chopper principle chopper cycle / using the mixed decay feature the tmc249 uses a quiet fixed frequency chopper. both coils are chopped with a phase shift of 180 degrees. the mixed decay option is realized as a self stabilizing system (pat. fi.), by shortening the fast decay phase, if the on phase becomes longer. it is advised to enable the mixed decay for each phase during the second half of e ach microstepping half - wave, when the current is meant to decrease. this leads to less motor resonance, especially at medium velocities. with low velocities or during standstill mixed decay should be switched off. in applications requiring high resolution, or using low inductivity motors, the mixed decay mode can also be enabled continuously, to reduce the minimum motor current which can be achieved. when mixed decay mode is continuously on or when using high inductivity motors at low supply voltage, it is advised to raise the chopper frequency to minimum 36khz, because the half chopper frequency could become audible under these conditions. when polarity is changed on one bridge, the pwm cycle on that bridge becomes restarted at once. fast decay switches off both upper transistors, while enabling the lower transistor opposite to the selected polarity. slow decay always enables both lower side transistors. r s e n s e s w c s w o s w c s w o i o n p h a s e : c u r r e n t f l o w s i n t a r g e t d i r e c t i o n r s e n s e i f a s t d e c a y p h a s e : c u r r e n t f l o w s b a c k i n t o p o w e r s u p p l y s w c s w o s w o r s e n s e i s l o w d e c a y p h a s e : c u r r e n t r e - c i r c u l a t i o n s w c s w o s w o s w c oscillator clock resp . external clock actual current phase a target current phase a mixed decay disabled mixed decay enabled on slow decay on fast decay slow decay
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 17 copyrigh t ? 2005, trinamic motion control gmbh & co kg adapting the sine wave for smooth motor operation after reaching the target cur rent in each chopper cycle, both, the slow decay and the fast decay cycle reduce the current by some amount. especially the fast decay cycle has a larger impact. thus, the medium coil current always is a bit lower than the target current. this leads to a f lat line in the current shape flowing through the motor. it can be corrected, by applying an offset to the sine shape. in mixed decay operation via spi, an offset of 1 does the job for most motors. blank time the tmc249 uses a digital blanking pulse for the current chopper comparators. this prevents current spikes, which can occur during switching action due to capaciti ve loading, from terminating the chopper cycle. the lowest possible blanking time gives the best results for microstepping: a long blank time leads to a long minimum turn - on time, thus giving an increased lower limit for the current. please remark, that th e blank time should cover both, switch - off time of the lower side transistors and turn - on time of the upper side transistors plus some time for the current to settle. thus the complete switching duration should never exceed 1.5s. with slow external power stages it will become necessary to add additional rc - filtering for the sense resistor inputs. the tmc249 allows adapting the blank time to the load conditions and to the selected slope in four steps (the effective resulting blank times are about 200ns sho rter in the non - a - type): blank time settings bl2 bl1 typical blank time gnd gnd 0.6 s gnd vcc 0.9 s vcc gnd 1.2 s vcc vcc 1.5 s t i t a r g e t c u r r e n t c o i l c u r r e n t t i t a r g e t c u r r e n t c o i l c u r r e n t c o i l c u r r e n t d o e s n o t h a v e o p t i m u m s h a p e t a r g e t c u r r e n t c o r r e c t e d f o r o p t i m u m s h a p e o f c o i l c u r r e n t
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 18 copyrigh t ? 2005, trinamic motion control gmbh & co kg classical non - spi control mode (stand alone mode) the driver can be controlled by analog current control signals and digital phase signals. to enable this mode, tie pin spe to gnd. in this mode, the spi interface is disabled and the spi input pins have alternate functions. the internal dacs are forced to 1111. pin functions in stand alone mode pin stand alone mode na me function in stand alone mode spe (gnd) tie to gnd to enable stand alone mode ann mdan enable mixed decay for bridge a (low = enable) sck mdbn enable mixed decay for bridge b (low = enable) sdi pha polarity bridge a (low = current flow from output o a1 to oa2) csn phb polarity bridge b (low = current flow from output ob1 to ob2) sdo err error output (high = overcurrent on any bridge, or over temperature). in this mode, the pin is never tri - stated. enn enn standby mode (high active), high causes a lo w power mode of the device. setting this pin high also resets all error conditions. ina, inb ina, inb current control for bridge a, resp. bridge b. refer to agnd. the sense resistor trip voltage is 0.34v when the input voltage is 2.0v. maximum input volt age is 3.0v. input signals for microstep control in stand alone mode attention : when transferring these waves to spi operation, please remark, that the mixed decay bits are inverted when compared to stand alone mode. 90 180 270 360 ina inb pha (sdi) phb (csn) mdan (ann) mdbn (sck) use dotted line to improve performance at medium velocities
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 19 copyrigh t ? 2005, trinamic motion control gmbh & co kg unipolar operation the tmc249 can also be used in a unipolar motor application with microstepping. in this configuration, only the four upper power transistors are required. differences of short circuit behavior in unipolar operation mode since there is no possibility to disable a short to vs condition, the circuit is not completely short circuit proof. in a low cost application a motor short would be covered, just using the bottom sense resistors (see schematic). differences in chopper cycle in unipolar operation mode in unipolar mode, one of the upper side transistors is chopped, depending on the phase polarity. slow decay mode always means, that both transistors are disabled. there is no difference between slow and fast decay mode, and the mixed decay control bits are dont care. the transistors have to stand an off voltage, which is slightly higher than the double of the supply voltage. voltage decay in the co il can be adapted to the application by adding additional diodes and a zener diode to feed back coil current in flyback conditions to the supply. ha1 la2 sra tmc249/ tmc239 ha2 p p la1 +v m one coil of the motor r s
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 20 copyrigh t ? 2005, trinamic motion control gmbh & co kg calculation of the external components sense resistor choose an appropriate sense resistor (r s ) to set th e desired motor current. the maximum motor current is reached, when the coil current setting is programmed to 1111. this results in a current sense trip voltage of 0.34v when the internal reference or a reference voltage of 2v is used. when operating yo ur motor in fullstep mode, the maximum motor current is as specified by the manufacturer. when operating in sinestep mode, multiply this value by 1.41 for the maximum current (i max ). r s = v trip / i max in a typical application: r s = 0.34v / i max r s : c urrent sense resistor of bridge a, b v trip : programmed trip voltage of the current sense comparators i max : desired maximum coil current examples for sense resistor settings r s i max 0.47 723ma 0.33 1030ma 0.22 1545ma 0.15 2267ma 0.10 3400ma hi gh side overcurrent detection resistor r sh the tmc249 detects an overcurrent to ground, when the voltage between vs and vt exceeds 150mv. the high side overcurrent detection resistor should be chosen in a way that 100mv voltage drop are not exceeded betwee n vs and vt, when both coils draw the maximum current. in a sinestep application, this is when sine and cosine wave have their highest sum, i.e. at 45 degrees, corresponding to 1.41 times the maximum current setting for one coil. in a fullstep application this is the double coil current. in a microstep application: r sh = 0.1v / (1.41 i max ) in a fullstep application: r sh = 0.1v / (2 i max ) r sh : high side overcurrent detection resistor i max : maximum coil current however, if the user desires to us e higher resistance values, a voltage divider in the range of 10 to 100 can be used for vt. this might also be desired to limit the peak short to gnd current, as described in the following chapter. attention : a careful pcb layout is required for the s ense resistor traces and for the r sh traces.
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 21 copyrigh t ? 2005, trinamic motion control gmbh & co kg making the circuit short circuit proof in practical applications, a short circuit does not describe a static condition, but can be of very different nature. it typically involves inductive, resistive and capaci tive components. worst events are unclamped switching events, because huge voltages can build up in inductive components and result in a high energy spark going into the driver, which can destroy the power transistors. the same is true when disconnecting a motor during operation: never disconnect the motor during operation! there is no absolute protection against random short circuit conditions, but pre - cautions can be taken to improve robustness of the circuit: in a short condition, the current can becom e very high before it is interrupted by the short detection, due to the blanking during switching and internal delays. the high - side transistors allow a high current flowing for the selected blank time. the lower the external inductivity, the faster the cu rrent climbs. if inductive components are involved in the short, the same current will shoot through the low - side resistor and cause a high negative voltage spike at the sense resistor. both, the high current and the voltage spikes are a danger for the dri ver. thus there are three things to be done, if short circuits are expected: 1. protect sra/srb inputs using a series resistance 2. increase r sh to limit maximum transistor current: use same value as for sense resistors 3. use as short as possible blank time th e second measure effectively limits short circuit current, because the upper driver transistor with its fixed on gate voltage of 6v forms a constant current source together with its internal resistance and r sh . a positive side effect is that only one type of low ohmic resistor is required. the drawback is that power dissipation increases. a high side short detection resistor of 0.33 ohms limits maximum high side transistor current to typically 4a. the schematic shows the modifications to be done. however , the effectiveness of these measures should be tested in the given application. +vm gnd r sb r sa r sh c vm 100r vs vt 100r 100r sra srb gnd 100nf r div internal r div values for reference microstep: 27r fullstep: 18r ina/inb up to3v 18r 12r r sh =r sa =r sb
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 22 copyrigh t ? 2005, trinamic motion control gmbh & co kg oscillator capacitor the pwm o scillator frequency can be set by an external capacitor. the internal oscillator uses a 28k resistor to charge / discharge the external capacitor to a trip voltage of 2/3 vcc respectively 1/3 vcc. it can be overdriven using an external cmos level square w ave signal. do not set the frequency higher than 100khz and do not leave the osc terminal open! the two bridges are chopped with a phase shift of 180 degrees at the positive and at the negative edge of the clock signal. f osc : pwm osc illator frequency c osc : oscillator capacitor in nf table of oscillator frequencies f osc typ. c osc 16.7khz 1.5nf 20.8khz 1.2nf 25.0khz 1.0nf 30.5khz 820pf 36.8khz 680pf 44.6khz 560pf please remark that an unnecessary high frequency leads to high switching losses in the power transistors and in the motor. for most applications a chopper frequency slightly above audible range is sufficient. when audible noise occurs in an application, especially with mixed decay continuously enabled, the chopper fre quency should be two times the audible range. pull - up resistors on unused inputs the digital inputs all have integrated pull - up resistors, except for the enn input, which is in fact an analog input. thus, there are no external pull - up resistors required f or unused digital inputs which are meant to be positive. power supply sequencing considerations upon power up, the driver initializes and switches off the bridge power transistors. however, in order for the internal startup logic to work properly, the vcc supply voltage has to be at least 1.0v, respectively, the vs supply voltage has to be at least 5.0v. when vs goes up with vcc at 0v, a medium current temporary cross conduction of the power stage can result at supply voltages between 2.4v and 4.8v. in thi s voltage range, the upper transistors conduct, while the gates of the lower transistors are floating. while this typically does no harm to the driver, it may hinder the power supply from coming up properly, depending on the power supply start up behavior. there are two possibilities to prevent this from occurring: add resistors from the la and lb outputs to gnd in the range of 1m keeping the low side n - channel mosfets gates at gnd. alternatively, either use a dual voltage power supply, or use a local regulator, generating the 5v or 3.3v vcc voltage. please pay attention to the local regulator start up voltage: some newer switching regulators do not start, before the input voltage has reached 5v. therefore it is recommended to use a standard linear reg ulator like 7805 or lm317 series or a low drop regulator or a switching regulator like the lm2595, starting at relatively low input voltages. [nf] c s 40 1 f osc osc
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 23 copyrigh t ? 2005, trinamic motion control gmbh & co kg slope control resistor the output - voltage slope of the full bridge is controlled by a constant current gate charg e / discharge of the mosfets. the charge / discharge current for the mosfets can be controlled by an external resistor: a reference current is generated by internally pulling the slp - pin to 1.25v via an integrated 4.7k resistor. this current is used to ge nerate the current for switching on and off the power transistors. (in non - a - type the low side slopes are fixed to typ. +/ - 15ma corresponding to a 5k to 10k slope control resistor !) the gate - driver output current can be set in range of 2ma to 25ma by an external resistor: r slp : slope control resistor i out : controlled output current of the low - side mosfet driver the slp - pin can directly be connected to agnd for the fastest output - voltage slope (respectively maximum ou t put curren t). please remark, that there is a tradeoff between reduced electromagnetic emissions (slow slope) and high efficiency because of low dynamic losses (fast slope). typical slope times range between 100ns and 500ns. slope times below 100ns are not recomme nded, because they superimpose additional stress on the power transistors while bringing only very slight improvement in power dissipation. for applications where electromagnetic emission is very critical, it might be necessary to add additional lc (or ca pacitor only) filtering on the motor connections. for these applications emission is lower, if only slow decay operation is used. 7 . 4 [ma] i 123 r out slp ] [k 0 5 10 15 20 25 -i hdoff / +/-i ld r slp [kohm] 10 5 2 0 20 50 100 i hdon
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 24 copyrigh t ? 2005, trinamic motion control gmbh & co kg absolute maximum ratings the maximum ratings may not be exceeded under any circumstances. symbol parameter min max unit v s supply voltage - 0.5 36 v v sm supply and bridge voltage max. 20000s 40 v v cc logic supply voltage - 0.5 6.0 v i op gate driver peak current (1) 50 ma i oc gate driver continuous current 5 ma v i logic input voltage - 0.3 v cc +0.3v v v ia analog input voltage - 0.3 v cc +0.3v v i io maximum current to / from digital pins and analog inputs +/ - 10 ma v vt short - to - ground detector input voltage v s - 1v v s +0.3v v t j junction temperature - 40 150 (1) c t stg storage temperature - 55 150 c (1) internally limited electrical characteristics operational range symbol parameter min max unit t ai ambient temperature industrial (1) - 25 125 c t aa ambient temperature automotive - 40 125 c t j junction temperature - 40 140 c v s bridge supply voltage (a - type) 7 34 v v s bridge supply voltage (non - a - type) 7 30 v v cc logic supply voltage 3.0 5.5 v f clk chopper clock frequency 100 khz r slp slope control resistor 0 470 k (1) the circuit can be operated up to 140c, but output power derates.
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 25 copyrigh t ? 2005, trinamic motion control gmbh & co kg dc characteristics dc characteristics contain the spread of values guaranteed within the specified supply voltage and temperature range unless otherwise specifi ed. typical characteristics repr e sent the average value of all parts. logic supply voltage: v cc = 3.0 v ... 5.5 v, junction temperature: t j = - 40c 140c, bridge supply voltage : v s = 7 v34 v (unless otherwise spec i fied) symbol parameter conditi ons min typ max unit i ldon gate drive current low side switch on (non - a - type) v ld < 4v 10 15 25 ma i ldoff5 gate drive current low side switch off (non - a - type) v ld > 3v v cc = 5v - 15 - 25 - 35 ma i ldoff3 gate drive current low side switch off (non - a - typ e) v ld > 3v vcc = 3.3v - 10 - 15 - 20 ma i ldon gate drive current low side switch on (a - type) v s > 8v, r slp = 0k v ld < 4v 15 25 40 ma i ldoff gate drive current low side switch off (a - type) v s > 8v, r slp = 0k v ld > 4v - 15 - 25 - 40 ma i hdon gate drive current h igh side switch on v s > 8v, r slp = 0k v s - v hd < 4v - 15 - 25 - 40 ma i hdoff gate drive current high side switch off v s > 8v, r slp = 0k v s - v hd > 4v 15 30 40 ma i set deviation of current setting with respect to characterization curve deviation from standar d value, 10k 8v relative to v s - 5.1 - 6.0 - 8.0 v v gl1 gate drive voltage low side on v s > 8v 5.1 6.0 8.0 v v gh0 gate drive voltage high side off relative to v s 0 - 0.5 v v gl0 gate drive voltage low side off 0 0.5 v v gcl gate driver clamping voltage - i h / i l = 20ma 12 16 20 v v gcli gate driver inverse clamping voltage - i h / i l = - 20ma - 0.8 v
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 26 copyrigh t ? 2005, trinamic motion control gmbh & co kg symbol parameter conditions min typ max unit v ccuv vcc undervoltage 2.5 2.7 2.9 v v cc ok vcc voltage o.k. 2.7 2.9 3.0 v i cc vcc supply current f osc = 25 khz 0.85 1.35 ma i ccstb vcc supply current standby 0.45 0.75 ma i ccsd vcc supply current shutdown enn = 1 37 70 a v suv vs undervoltage 5.5 5.9 6.2 v v ccok vs voltage o.k. 6.1 6.4 6.7 v i ssm vs supply current with maximum current setting (static state) v s = 14v, r slp = 0k 6 ma i ssd vs supply current shutdown or standby v s = 14v 28 50 a v ih high input voltage (sdi, sck, csn, bl1, bl2, spe, ann) 2.2 vcc + 0.3 v v v il low input voltage (sdi, sck, csn, bl1, bl2, spe, ann) - 0.3 0.7 v v ihys input voltage hysteresis (sdi, sck, csn, bl1, bl2, spe, ann) 100 300 500 mv v oh high output voltage (output sdo) - i oh = 1ma vcc C C ol low output voltage (output s do) i ol = 1ma 0 0.1 0.4 v - i isl low input current (sdi, sck, csn, bl1, bl2, spe, ann) v i = 0 v cc = 3.3v v cc = 5.0v 2 10 25 70 a a a v ennh high input voltage threshold (input enn) 1/2 vcc v ehys input voltage hysteresis (input enn) 0.1 v ennh v osch high input voltage threshold (input osc) tbd 2/3 vcc tbd v v oscl low input voltage threshold (input osc) tbd 1/3 vcc tbd v v vtd vt threshold voltage (referenced to vs) - 130 - 155 - 180 mv v trip sra / srb voltage at dac=1111 srs sra / srb overcurrent detection threshold 570 615 660 mv v sroffs1 sra / srb comparator offset voltage (standard device) - 10 0 10 mv v sroffs2 sra / srb comparator offset voltage (selected device) - 6 0 6 mv r inab ina / inb input resistance vin 3 v 175 264 360 k
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 27 copyrigh t ? 2005, trinamic motion control gmbh & co kg ac characteristics ac characteristics contain the spread of values guaranteed within the specified supply voltage and temperature range unless otherwise specified. typical characteristics repr e sent the ave rage value of all parts. logic supply voltage: v cc = 3.3v, bridge supply voltage: v s = 14.0v, ambient temperature: t a = 27c, external mosfet gate charge = 3.2nc symbol parameter conditions min typ max unit f osc oscillator frequency using internal osc illator c osc = 1nf 1% 20 25 31 khz t bl effective blank time bl1, bl2 = v cc 1.35 1.5 1.65 s t onmin minimum pwm on - time bl1, bl2 = gnd 0.7 s thermal protection symbol parameter conditions min typ max unit t jot thermal shutdown 145 155 165 c t j othys t jot hysteresis 15 c t jwt prewarning temperature 135 145 155 c t jwthys t jwt hysteresis 15 c
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 28 copyrigh t ? 2005, trinamic motion control gmbh & co kg spi interface timing propagation times (3.0 v vcc 5.5 v, - 40c tj 150c; v ih = 2.8v, v il = 0.5v; tr, tf = 10ns; c l = 50pf, unless o therwise specified) symbol parameter conditions min typ max unit f sck sck frequency enn = 0 dc 4 mhz t 1 sck stable before and after csn change 50 ns t ch width of sck high pulse 100 ns t cl width of sck low pulse 100 ns t du sdi setup time 40 ns t dh sdi hold time 50 ns t d sdo delay time c l = 50pf 40 100 ns t zc csn high to sdo high impedance *) 50 ns t es enn to sck setup time 30 ns t pd csn high to la / ha / lb / hb output polarity change delay **) 3 t osc + 4 s t ld load indica tor valid after la / ha / lb / hb output polarity change 5 7 s *) sdo is tristated whenever enn is inactive (high) or csn is inactive (high). **) whenever the pha / phb polarity is changed, the chopper is restarted for that phase. however, the choppe r does not switch on, when the sra resp. srb comparator threshold is exceeded upon the start of a chopper period. using the spi interface the spi interface allows either cascading of multiple devices, giving a longer shift register, or working with a sepa rate chip select signal for each device, paralleling all other lines. even when there is only one device attached to a cpu, the cpu can communicate with it using a 16 bit transmission. in this case, the upper 4 bits are dummy bits. spi filter to prevent s pikes from changing the spi settings, spi data words are only accepted, if their length is at least 12 bit. t 1 sdo sdi sck csn t es t 1 t 1 t cl t ch bit11 bit10 bit0 bit11 bit10 bit0 t d t zc t du t dh enn
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 29 copyrigh t ? 2005, trinamic motion control gmbh & co kg application note: extending the microstep resolution for some applications it might be desired to have a higher microstep resolution, while keeping the advantages of control via the serial interface. the following schematic shows a solution, which adds two lsbs by selectively pulling up the sra / srb pin by a small voltage difference. please remark, that the lower two bits are inverted in the depicte d circuit. a full scale sense voltage of 340mv is assumed. the circuit still takes advantage of completely switching off of the coils when the internal dac bits are set to 0000. this results in the following comparator trip voltages: current setting (m sb first) trip voltage 0000xx 0 v 000111 5.8 mv 000110 11.5 mv 000101 17.3 mv 000100 23 mv ... 111101 334.2 mv 111100 340 mv spi bit 15 14 13 12 11 10 9 8 dac bit /b1 /b0 /a1 /a0 mda a5 a4 a3 spi bit 7 6 5 4 3 2 1 0 dac bit a2 pha mdb b5 b4 b3 b2 phb please see the faq document for more application information. r s sra tmc236 / tmc239 110r 4.7nf opt. 74hc595 c1 q0 q1 q2 q3 q4 q5 q6 q7 q7' /mr c2 /oe sck sdi sdo csn +v cc ds1d 100k /cs sdi sck sdo free for second tmc239 47k 47k 47k /daca.0 /daca.1 /dacb.0 /dacb.1 vcc = 5v 1/2 74hc74 c d q note: use a 74hc4094 instead of the hc595 to get rid of the hc74 and inverter
tmc249 / tmc249a data sheet (v2.09 / 2009 - jul - 30) 30 copyrigh t ? 2005, trinamic motion control gmbh & co kg documentation revision version author des cription v2.06 bd added power supply sequencing considerations v2.07 bd updated logo, minor additions v2.09 bd adapted style, added info on chopper cycle i spi is a trademark of motorola

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