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1 semiconductors description the ZXBM2004 is a 2-phase, dc brushless motor pre-driver with pwm variable speed control suitable for fan and blower motors. the controller is primarily intended for thermal control using a thermistor but can also be used for control using an external voltage or pwm signal. features ? pwm speed control via external thermistor ? ability to be able to set a minimum speed ? ability to be able to remove any speed change against supply voltage variation ? low noise ? built in lock detect protection, rotational speed sensing and automatic recovery ? built in hall amplifier allows direct connection to hall element ? speed (fg) pulse output ? rotor lock (rd) output ? up to 18v input voltage (60v with external regulator) ? so14n and qsop16 package options applications ? mainframe and personal computer fans and blowers ? instrumentation fans ? central heating blowers ? automotive climate control device marking so14: zetex ZXBM2004 date code ZXBM2004 provisional issue h - july 2003 variable speed 2-phase fan motor controller for thermistor control device reel size tape width quantity per reel ZXBM2004n14ta 7" (180mm) 16mm 500 ZXBM2004n14tc 13" (330mm) 16mm 2,500 ordering information - so14n s o 1 4 device reel size tape width quantity per reel ZXBM2004q16ta 7" (180mm) 12mm 500 ZXBM2004q16tc 13" (330mm) 12mm 2,500 ordering information - qsop16 qsop16 qsop16: zetex bm2004 date code
ZXBM2004 semiconductors provisional issue h - july 2003 2 parameter symbol min typ max unit conditions supply voltage v cc 4.7 18 v supply current i cc 5.5 7.5 ma no load 1 hall amp input voltage v in 40 mv diff p-p hall amp common mode voltage v cm 0.5 vcc-1.5 v hall amp input offset v ofs 7 mv hall amp bias current i bs 400 700 na ph1, ph2 output high v oh v cc -2.2 v cc -1.8 v i oh =80ma ph1, ph2 output low v ola 0.4 0.6 v i ol =16ma 2 ph1, ph2 output low v olb 0.4 0.6 v i ol =50 a 3 ph1, ph2 output source current i oh -80 ma ph1, ph2 output sink current i ol 16 ma c pwm charge current i pwmc -5.0 -6.0 -7.0 a c pwm discharge current i pwmd 50 62 75 a c pwm high threshold voltage v thh 3v c pwm low threshold voltage v thl 1v pwm frequency f pwm 24 khz c pwm = 0.1nf thref voltage v thref 2.94 2.96 3 v i othref =100 a thref output current i othref -1 ma s min input current i ismin -0.25 -0.5 av in = 2v,spd=open spd voltage minimum v spdl 1 v 100% pwm drive spd voltage maximum v spdh 3 v 0% pwm drive spd input current i ispd -0.8 -2 av in =2v c lck charge current i lckc -2.8 -3.8 a c lck discharge current i lckd -0.46 -0.55 a c lck high threshold voltage v thh 3v c lck low threshold voltage v thl 1v lock condition on:off ratio 1:8 fg & rd low level output current i ol 5ma fg & rd low level output voltage v ol 0.5 v i ol =5ma notes: 1. measured with pins h+, h-, c lck and c pwm = 0v and all other signal pins open circuit. 2. measured when opposing phase output is low 3. measured when opposing phase output is high electrical characteristics (at tamb = 25c & vcc = 12v) parameter symbol limits unit supply voltage v ccmax -0.6 to 20 v input current i ccmax 200 ma power dissipation p dmax 500 mw operating temp. t opr -55 to 110 c storage temp. t stg -55 to 125 c absolute maximum ratings
ZXBM2004 semiconductors provisional issue h - july 2003 3 6 block diagram pin assignments
pin functional description h+ - hall input h- - hall input the rotor position is detected by a hall sensor whose output is applied to these pins. this sensor can be eithe r a 4 pin 'naked' hall device or of the 3 pin buffered switching type. fo r a 4 pin device the differential hall output signal is connected to the h+ and h- pins. for a buffered hall sensor the hall device output is attached to the h+ pin, with a pull-up attached if needed, whilst the h- pin has an external potential divider attached to hold the pin at half vcc. when h+ is high in relation to h-, ph2 is the active drive. thref - thermistor network reference this is a reference voltage of nominal 2.96v. it is designed for the ability to 'source' current into the 10k thermistor network therefore it will not 'sink' any current from a higher voltage. the total current drawn from the pin by the minimum speed potential divider to pin s min and by the thermistor network at maximum temperature should not exceed 1ma. spd - thermistor network input the thermistor network is attached to this pin. the resultant thermistor network voltage applied to the spd pin provides control over the fan motor speed by varying the pulse width modulated (pwm) drive ratio at the ph1 and ph2 outputs. the control signal takes the form of a voltage input of range 3v to 1v, representing 0% to 100% drive respectively. in normal operation a 10k ntc thermistor network as shown in the block diagram would be attached to the spd pin. if variable speed control is not required this pin can be left with an external potential divider to set a fixed speed or tied to ground to provide full speed i.e. 100% pwm drive. if required this pin can also be used as an enable pin. the application of a voltage >3.0v will to force the pwm drive fully off, in effect disabling the drive. c pwm - sets pwm frequency this pin has an external capacitor attached to set the pwm frequency for the phase drive outputs. a capacitor value of 0.1nf will provide a pwm frequency of typically 24khz. the c pwm timing period (t pwm ) is determined by the following equation: () () t= v-vxc i v-vxc i pwm thh thl pwmc thh thl pwmd + where: c = c pwm +15, - (in pf) v thh and v thl are the c pwm pin threshold voltages i pwmc and i pwmd are the charge and discharge currents (in a). t pwm in s as these threshold voltages are nominally set to v thh = 3v and v thl = 1v the equations can be simplified as follows: t= 2c i 2c i pwm pwmc pwmd + s min - sets minimum speed when using a thermistor to control a fan ? s speed it is possible that at low temperatures the fan might fail to start or if already running and the temperature drops the fan might stop. this is an undesirable condition to have in thermal controlled fans so the s min pin is used to set a minimum speed. the following graph illustrates a typical speed response characteristic for a thermally controlled fan. ZXBM2004 semiconductors provisional issue h - july 2003 4
when a potential divider is attached from this pin and between thref and gnd it sets a voltage on the pin. this voltage is monitored by the spd pin such that it cannot rise above it. as a higher voltage on the spd pin represents a lower speed it therefore restricts the lower speed range of the fan. if this feature is not required the pin is left tied to thref so no minimum speed will be set. if the fan is being controlled from an external voltage source either this feature should not be used or if it is required then a >1k resistor should be placed in series with the spd pin. gnd - ground this is the device supply ground return pin and will generally be the most negative supply pin to the fan. c lck - locked rotor timing capacitor should the fan stop rotating for any reason, i.e. an obstruction in the fan blade or a seized bearing, then the device will enter a rotor locked condition. in this condition after a predetermined time (t lock ) the rd pin will go high and the phase outputs will be disabled. after a further delay (t off ) the controller will re-enable the phase drive for a defined period (t on ) in an attempt to re-start the fan. this cycle of (t off ) and (t on ) will be repeated indefinitely or until the fan re-starts. the frequency at which this takes place is determined by the size of the capacitor applied to this c lck pin. for a 12v supply a value of 1uf will typically provide an 'on' (drive) period of 0.53s and an 'off' (wait) period of 4.3s, giving an on:off ratio of 1:8. the c lck timing periods are determined by the following equations: () t= vxc l t= v-v xc i lock thh lck lckc on thh thl lck l ckc () t= v-v xc i off thh thl lck lckd where: v thh and v thl are the c lck pin threshold voltages and i lckc and i lckd are the charge and discharge currents. as these threshold voltages are nominally set to v thh = 3v and v thl = 1v the equations can be simplified as follows: t= 3xc i t= 2c i t= 2c lock lck lckc on lck lckc off lck lckd i ZXBM2004 semiconductors provisional issue h - july 2003 5 -10 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 80 90 10 0 set minimum speed typical temperature response fan speed (%) temperature (?c)
rd - locked rotor error output this pin is the locked rotor output as referred to in the c lck timing section above. it is high when the rotor is stopped and low when running. this is an open collector drive giving an active pull down with the high level being provided by an external pull up resistor. fg - frequency generator (speed) output this is the frequency generator output and is a buffered signal from the hall sensor. this is an open collector drive giving an active pull down with the high level being provided by an external pull up resistor. ph1 - phase 1 external transistor driver ph2 - phase 2 external transistor driver these are the phase drive outputs and are darlington emitter follower outputs with an active pull-down to help faster switch off when using bipolar devices. the outputs are designed to provide up to 80ma of drive when high to the base or gates of external transistors as shown in the typical application circuit following. the external transistors in turn drive the fan motor windings. in addition the active phase drive is capable of sinking up to 16ma when driving low to aid turn off times during pwm operation. when the phase is inactive the output is held low by an internal pull-down resistor v+op - phase outputs supply voltage this pin is the supply to the phase outputs and will be connected differently dependant upon external transistor type. for bipolar devices this pin will be connected by a resistor to the v cc pin. the resistor is used to control the current into the transistor base so its value is chosen accordingly. for mosfet devices the pin will connect to the v cc pin v cc - applied voltage this is the device internal circuitry supply voltage. for 5v to 12v fans this can be supplied directly from the fan motor supply. for fans likely to run in excess of the 18v maximum rating for the device this will be supplied from an external regulator such as a zener diode. rd and fg timing waveform: lock timing example: using the equation previously described and to be found under the c lck pin description: t= 3xc i t= 2c i t= 2c lock lck lckc on lck lckc off lck lckd i using a value of c lck = 1.0uf together with the values of i lckc and i lckd to be found in the electrical characteristics we can derive the following timings for operation at 12v and 25 c: t= 3x1uf 3.8 a = 0.79s t = 2x1uf 3.8 a lock on = 0.526 s t= 2x1uf 0.46 a off =435 . s ZXBM2004 semiconductors provisional issue h - july 2003 6
applications information this section is intended to give a brief insight into using the ZXBM2004. more complete data covering all applications aspects of this and other zxbm series of fan motor pre-drivers is available from the zetex website www.zetex.com or from your nearest zetex office. the ZXBM2004 device is a development of the zxbm2001 to zxbm2003 series of fan motor controller that has been specifically developed for use in thermistor temperature control situations. the main feature of the device is the ability to set a minimum speed at which the fan will run. two application circuits are illustrated here and both show slightly differing ways in which the ZXBM2004 controller can be used. for example figure 1 is a simple solution and employs bipolar driver transistors and a naked hall device whilst the figure 2 employs mosfet devices, a buffered hall device and speed vs supply change normalisation and a kick-start feature. these differing features will be described in detail in the following sections. the phase outputs the phase outputs on the ZXBM2004 2-phase dc brushless motor pre-driver have been designed to be capable of driving both bipolar or mosfet power transistors. the output stage consists of both active pull-up and active pull-down devices for optimum pwm switching. pulling up, the output can deliver a maximum of 80ma whilst pulling down, sinking 16ma is possible. this is particularly useful for driving bipolar devices where for fast turn-off it is important to remove base stored charge as quickly as possible. figure 1 shows an application circuit for driving bipolar devices. the normal practice when driving a bipolar device would be to use a base series resistor to control and limit the current into the base. however the problem with this would be that the resistor would also restrict the removal of the base stored charge at switch-off. in order to keep turn-off times as short as possible it is therefore preferable to remove the base resistor and apply the current limiting in the supply to the output stage. this is not too dissimilar from the approach taken by conventional totem-pole output stages in ttl devices. in the case of the ZXBM2004 the current limiting is applied by inserting a resistor from v+op to the v cc pin. the current applied to the base of q1 and q2 in figure 1 is determined by: () r3 = v 1.8 + 0.7 i cc out - where: 1.8 is the voltage drop due to the phase drive output stage. 0.7 is the voltage dropped across the base-emitter of q1/q2. i out is the drive required by the external phase drive transistors q1/q2. the circuit example in figure 1 has the external drive (i out ) set to approximately 30ma. ZXBM2004 semiconductors provisional issue h - july 2003 7
when driving mosfets a more conventional approach is employed in that each mosfet will have a gate limiting resistor to control turn-on and turn-off. the v+op pin will then be connected directly to the supply i.e. the vcc pin. figure 2 illustrates this. ZXBM2004 semiconductors provisional issue h - july 2003 8 ZXBM2004 ph1 ph2 v cc gnd h+ h- c pwm c lck spd rd 12v q1 w1 c1 c2 c3 1 f 100pf 1 f zd1 47v q2 w2 zd2 47v c5 2.2 f fcx 1053a d1 d2 1n4148 1n4004 hall 0v fg c4 0.1 f r9 r therm 10k ? ntc 2k ? r3 330 ? v+op fg thref s min rd r5 33k ? r7 5.1k ? r6 12k ? fcx 1053a r4 30k ? figure 1: typical application circuit utilising bipolar power transistors and a naked hall device. 12v q1 r1 #5 w1 100 ? zxmn 6a07z zd1 d3 47v 1n4148 q2 r2 #5 w2 100 ? zd2 d4 47v 1n4148 c5 #6 2.2 f zxmn 6a07z hall 0v fg c4 #2 0.1 f r therm 10k ? ntc rd r5 33k ? r7 91k ? r8 #1 15k ? r6 100k ? r10 r9 #4 r11 33k ? 33k ? 33k ? r4 30k ? ZXBM2004 ph1 ph2 v cc gnd h+ h- c pwm c lck spd rd c1 c2 c3 1 f 100pf 1 f d1 d2 1n4148 1n4004 v+op fg thref s min c5 #3 1 f figure 2: typical application circuit utilising mosfet power transistors and a buffered hall device. notes: components marked # are related to specific features or fan requirements and their use is user dependent. #1 r8 is required if the fan is being designed to give constant speed in mid range when the supply voltage varies. #2 c4 will be required where the thermistor is some distance from the ZXBM2004 or in high power fan or blower applications. #3 c5 performs a kick-start to the fan if a minimum speed lower than or close to the fans practical starting speed is being used . #4 r9 is only needed if it is not included in the hall device. #5 the normal practice with mosfets is to include a series resistor with the gate to prevent oscillations, however dependent upo n the characteristics of the mosfets being used it has been found that these can be omitted.
thermal control the ZXBM2004 has been specifically designed for use in thermal control applications where a thermistor is employed for temperature sensing. in most applications, it is expected that the user will wish to set their own temperature response characteristics. to do this a 10k ntc thermistor can be employed in conjunction with a pair of resistors to set such parameters as the speed at 25 c and the slope of the response up to full speed. r6 and r7 attached to pin spd in both figures are used to set the temperature response. the ratio between the two resistors will enable the user to set the speed of the fan at 25 c. this is influenced by the mechanical response of the fan and also by the inductance of the stator windings so the resistor ratio needs to be adjusted by trial to take this into account. the ratio of r6 compared to the 10k of the thermistor will determine the slope. raising the value of r6 in relation to the thermistor will give a steeper slope, for example say 50% speed at 25 c and full speed at 40 c as is shown in figure 2, whereas lowering the value will make the slope shallower, for example 50% speed at 25 c and full speed at 55 c as in figure 1. minimum speed one of the main features of the ZXBM2004 is the ability to set a minimum speed that the fan will run. this will avoid the fan stopping at low temperatures and also ensures the fan will always start when cold. r4 and r5 in both figures are used to set a voltage on the pin s min . this voltage represents the voltage above which the voltage of the thermistor network on the spd pin cannot rise. the best approach to set up a fan for this feature is to run the fan at the desired minimum speed by applying a voltage to the spd pin with the thref pin open circuit. measure the voltage on the spd pin and set that voltage using the potential divider r4 and r5 between the thref and ground. if the minimum speed feature is not required the pin is left open circuit, however in noisy environments it might be better to connect it to pin thref. note: it should not be connected to ground as this will represent a minimum speed of full speed. the addition of a capacitor on pin s min will cause the fan to start with a higher percentage of pwm drive than when running. it is normal that a fan will run at a lower speed than that at which it can start so this feature can be useful where a fan's minimum speed is set very low and therefore it might not always start. it in effect gives the fan a kick to start it. the size of the capacitor required will depend upon the motor size however, it is suggested that 470 f to 1mf would be a suitable starting point. speed vs supply change normalisation with the ZXBM2004, and by the addition of one resistor, it is possible to set the thermistor network so as the fan s speed remains constant when the supply voltage changes. this is very useful where a fan is to be specified over a large supply voltage range. figure 2 illustrates a circuit where the feature is included. in this case resistor r8 is added into the thermistor network between the supply and the spd pin. the value chosen for r8 will be dependent upon the fan s characteristics but will be typically in the range 20k to 100k dependent upon motor winding characteristics. the precise value is best determined by trial but it should be pointed out that in order to keep the same temperature response characteristics the value of r7 will also need to be increased in compensation as the two resistors are in effect in parallel but sourced from different voltages. ZXBM2004 semiconductors provisional issue h - july 2003 9
external voltage and pwm control as an alternative to control by a thermistor it is also possible to control the speed of the fan by a signal from an external source. this signal may be either a control voltage or pwm waveform signal. when a voltage signal is used it will be applied to the spd pin and should vary between 1v representing full speed (100% pwm drive) and 3v representing 0% pwm drive. in practice, and dependant upon the other aspects of the motor design, low speed might be represented by 50% pwm drive. if the minimum speed feature is required then the signal should be applied to the ZXBM2004 spd pin via a 2.2k resistor to allow the internal minimum speed circuit to over-ride the control voltage. where control is required using an externally generated pwm signal the spd pin should be left open circuit and the pwm signal applied to the c pwm pin. the signal can be a conventional 5v or 3.3v ttl or cmos compatible waveform. a potential divider of say two 47k resistors should be placed between thref and gnd pins and connected to the c lck pin. where control is required using an externally generated pwm signal the spd pin should have a potential divider added between g nd and v cc . the resistors be typically 10k . the pwm signal is applied directly to the cpwm pin and can be a conventional 5v or 3.3v ttl or cmos compatible waveform. ZXBM2004 semiconductors provisional issue h - july 2003 10 bipolar types (npn) v ceo (v) i c (a) min h fe @i c v ce(sat) max(mv) @ ic/ib package fmmt619 50 2 300 @ 0.5a 220 @ 1a / 10ma s ot23 fcx619 50 3 200 @ 1a 220 @ 1a / 10ma s ot89 zxt13n50de6 50 4 300 @ 1a 100 @ 1a / 10ma sot23-6 fzt851 60 6 100 @ 2a 100 @ 1a / 10ma sot223 fcx1053a 75 4.5 300 @ 0.5a 200 @ 1a / 10ma sot89 fzt853 100 6 100 @ 2a 175 @ 1a / 100ma sot223 fzt855 150 4 100 @ 1a 65 @ 0.5a / 50ma sot223 a selection of suitable transistors and mosfets mosfet types (n-channel) v ds (v) i d (a) i peak (a) (pulsed) r ds(on) max(m ) @v gs = 10v package zxmn3a04dn8 30 7.6 25 20 so8 (dual) zxmn6a09dn8 60 5 17.6 45 so8 (dual) zxmn6a07f 60 1 4 45 sot23 zxmn6a11z 60 3.8 10 140 sot89 zxmn6a11g 60 3.8 10 140 sot223 zxmn6a09k 60 11.2 40 45 dpak zxmn10a09k 100 7.1 25 90 dpak zxmn10a11g 100 1.9 5.9 600 sot223
note: dimensions in inches are control dimensions dimensions in millimetres are approximate ZXBM2004 semiconductors provisional issue h - july 2003 europe zetex plc fields new road chadderton oldham, ol9 8np united kingdom telephone (44) 161 622 4444 fax: (44) 161 622 4446 hq@zetex.com zetex gmbh streitfeldstra e19 d-81673 m ? nchen germany telefon: (49) 89 45 49 49 0 fax: (49) 89 45 49 49 49 europe.sales@zetex.com americas zetex inc 700 veterans memorial hwy hauppauge, ny 11788 usa telephone: (1) 631 360 2222 fax: (1) 631 360 8222 usa.sales@zetex.com asia pacific zetex (asia) ltd 3701-04 metroplaza tower 1 hing fong road kwai fong hong kong telephone: (852) 26100 611 fax: (852) 24250 494 asia.sales@zetex.com these offices are supported by agents and distributors in major countries world-wide. this publication is issued to provide outline information only which (unless agreed by the company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. the company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. for the latest product information, log on to www.zetex.com ? zetex plc 2003 11 package outline so14n dim inches millimetre min. max. min. max. a 0.053 0.069 1.35 1.75 a1 0.004 0.010 0.10 0.25 d 0.337 0.344 8.55 8.75 h 0.228 0.244 5.80 6.20 e 0.150 0.157 3.80 4.00 l 0.016 0.050 0.40 1.27 e 0.050 bsc 1.27 bsc b 0.013 0.020 0.33 0.51 c 0.008 0.010 0.19 0.25 0 8 0 8 h 0.010 0.020 0.25 0.50 package dimensions package outline qsop16 dim inches millimetre min. max. min. max. a 0.053 0.069 1.35 1.75 a1 0.004 0.010 0.10 0.25 a2 0.049 0.059 1.25 1.50 d 0.189 0.197 4.80 5.00 zd 0.009 ref 0.23 bsc e 0.228 0.244 5.79 6.20 e1 0.150 0.157 3.81 3.99 l 0.016 0.050 0.41 1.27 e 0.025 bsc 0.64 bsc b 0.008 0.012 0.20 0.30 c 0.007 0.010 0.18 0.25 0 8 0 8 h 0.010 0.020 0.25 0.50 package dimensions

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