unisonic technologies co., ltd m7206 cmos ic www.unisonic.com.tw 1 of 8 copyright ? 2013 unisonic technologies co., ltd qw-r502-q37.a 3 1/2 lcd display driver, a/d converters ? description the utc m7206 is a 3 1/2 a/d converter ic with low power supply and excellent performance, which also can greatly refrain form interfering. the m7206 combines seven -phase decoder, display driver, reference source, clock system and back light polarity driver, so it can directly drive lcd. com pared with other products, the m7206 adds a new function that can detect on-off state and then alarm. the m7206 covers high-precision, good compatibility and low-cost in all. it can achieve auto-zero adjustment error less than 10uv, zero drift within 1uv/c, input current below 10pa and converter error under 1 count. ? features * on-off state detecting and alarming * zero auto-adjustment, guaranteed zero reading with zero input. * true polarity indication for precision null detection. * differential inputs and differential reference. * triplex lcd display. * convenient 9v battery operation * cmos differential inputs for high impedance and null attenuation * low noise and a/d converter, * low noise a/d converter, stable display. * inner clock circuit , can form ast able multi-vibrator by connecting passive electronic component. * optional exterior clock signal input * has triggered buttons that keep and low voltage alarm function that power * on-chip voltage reference, 60ppm/c drift. ? ordering information ordering number package packing lead free halogen free m7206l-ql1-y m7206g-q l1-y lqfp-44 tray
m7206 cmos ic unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r502-q37.a ? pin configurations ? pin description pin name type pin description 1 bz o piezo buzzer output. whenever bzen is connected to v+ and differential inputs are tied toget her, bz will generate a 5khz sound output. 2 bzen i buzzer control slave input. this pin is internally pulled-down to test.see bz 3 test - digital gnd. pull high to v+ all lcd segments will be activated. 4 osc3 - crystal oscillator connection. (rc) 5 hold o hold control pin. when it receives a negative mud pulse, display hold; receive again then function disabled. 6 osc2 - crystal oscillator connection. (output) 7 osc1 - crystal oscillator connection. (input) 8 v+ p positive supply voltage 9 15 a1~g1 o lcd segment drive (unit) 16 21 32 a2~g2 o lcd segment drive (decade) 22~25, 29~31 a3~g3 o lcd segment drive (hundred) 26 ab4 o lcd segment drive (thousand). w hen the readout exceeds 1999, ab4 drive the segment of thousand to display ?1? for showing excess. 27 pol o lcd segment drive. (minus ?-?) 28 bp o lcd common drive. 33 lowb o lcd segment drive. (low battery) 34 v- p negative supply voltage. con necting to battery negative terminal. 35 int - integrator output. 36 buff - integration register connection 37 a/z - auto-zero capacitor connection 38 in lo i analog low input signal 39 in hi i analog high input signal 40 common o set the common-mode voltage for the system 41 c-ref- - negative capacitor connection for on-chip a/d converter 42 c-ref+ - positive capacitor connection for on-chip a/d converter 43 ref lo i low differential reference input connection. 44 ref hi i high differential reference input connection
m7206 cmos ic unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r502-q37.a ? pin figure ? pin coordinates pin name coordinate pin name coordinate x y x y 1 bz 2135 325 24 f3 130 2115 2 bzen 2135 475 25 e3 95 1965 3 test 2135 625 26 ab4 95 1815 4 osc3 2135 885 27 pol 95 1665 5 hold 2135 1035 28 bp 95 1515 6 osc2 2135 1185 29 hldo 95 1365 7 osc1 2135 1335 30 bp- 95 1165 8 v+ 2135 1550 31 g3 95 1015 9 d1 2135 1710 32 a3 95 865 10 c1 2135 1860 33 c3 95 715 11 b1 2135 2010 34 g2 95 565 12 a1 1970 2115 35 lb 95 415 13 f1 1820 2115 36 v- 95 265 14 g1 1670 2115 37 int 570 95 15 e1 1520 2115 38 buf 725 95 16 d2 1370 2115 39 az 880 95 17 c2 1220 2115 40 in lo 1030 95 18 b2 1070 2115 41 in hi 1350 95 19 a2 920 2115 42 com 1510 95 20 f2 770 2115 43 cref- 1670 95 21 e2 620 2115 44 cref+ 1820 95 22 d3 470 2115 45 rf lo 1970 95 23 b3 320 2115 46 rf hi 2120 95
m7206 cmos ic unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r502-q37.a ? block diagram
m7206 cmos ic unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r502-q37.a ? absolute maximum rating (unless otherwise specified) parameter symbol ratings unit power supply voltage v+ v- v cc 12 v analog input voltage v iang v+~v- v reference input voltage v iref v+~v- v operating temperature range t opr 0 ~ 70 c storage temperature t stg -65 ~ +150 c note: absolute maximum ratings are those values be yond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? electrical characteristics (v cc 9v, t a =25c, unless otherwise specified) parameter symbol test conditions min typ max unit v cc range v cc 9 v supply current(does not conclude common current ) i cc v in =0v 0.6 1.2 ma dc characteristics zero input reading v in =0v, full-scale=200mv -000.0 000.0 +000.0 digital reading ratio metric reading v in =v ref, v ref =100mv 999 999/ 1000 1001 digital reading linearity (max. deviation form best straight line fit) full-scale=200.0mv or full-scale=2.0v -1 0.2 +1 counts roll-over error -v in =+v in ~ 200mv -1 0.2 +1 counts input leakage current v ih =0v 1 10 pa low battery flag v+ to v- 6.6 6.9 7.2 v analog common voltage ( with respect to v+) 25k ? between common and positive supply 2.80 3.00 3.20 v
m7206 cmos ic unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r502-q37.a ? typical applications circuits figure 1
m7206 cmos ic unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r502-q37.a ? detailed description analog section the measurement cycle of analog secti on is divided into three phases. they are (1)auto-zero(a-z),(2) signal integrate(int)and (3) de-integrate(de). auto-zero phase during auto-zero three things happen. first, input high and low are disconnected from the pins and internally shorted to analog common. second, the reference capacitor is charged to t he reference voltage. third, a feedback loop is closed around the system to charge the auto-zero capacitor c az to compensate for offset voltages in the buffer amplifier, integrator and comparat or. since the comparator is included in the loop, the a-z accuracy is limited only by the noise of the system. in any case, t he offset referred to the input is less than 10uv. signal integrate phase during signal integrate the auto-zero lo ops are opened, the internal short is re moved, and the internal inputs high and low are connected to the external pins. the converter then integrates the different ial voltage between inhi and inlo for a fixed time. this differential voltage can be with in a wide common mode range: up to 1v from either supply. on the other hand, if the input signal has no return with re spect to the converter power supply, in lo can be tied to analog common to establish the correct common mode volt age. at the end of this phas e, the polarity of the integrated signal is determined. de-integrate phase the final phase is de-integrated, or reference integrates . input low is internally connected to analog common and input high is connected across the previously charged refer ence capacitor. circuitry within the chip ensures that the capacitor will be connected with the correct polarity to cause the integrator output to return to zero. the time required for the output to return to zero is proportional to the i nput signal. specifically the digital reading displayed is: display count=1000(v in /v ref ) differential input the input can accept differential voltages anywhere with in the common mode range of the input amplifier, or specifically from 0.5v below the posit ive supply to 1v above the negative suppl y. in this range, the system has a cmrr of 86db typical. however, we must make sure that the integrator out put does not saturate. a worst case condition would be a large positive common mode voltage with a near full scale negative differential input voltage. the negative input signal drives the in tegrator positive when most of its swing has been used up by the positive common mod e voltage. for thes e critical applications t he integrator output swing ca n be reduced to less than the recommended 2v full scale swing with little loss of accuracy. the integrator output can swing to within 0.3v of either supply without loss of linearity. differential reference the reference voltage can be generated any where within the power supply volt age of the converter. the main source of common mode error is a roll-over voltage caused by the reference capacitor losing or gaining charge to stray capacity on its nodes. if there is a large common mode voltage, the reference capacitor can gain change when called up to de-integrate a positive signal but lose charge when called up to de-integrate a negative input signal. this difference in reference for positive or negative input volt age will give a roll-over error. however, by selecting the reference capacitor such that it is la rge enough in comparison to the stray capac itance, this error can be held to less than 0.5 count worst case. analog common the com pin is used to set the common-mod voltage for the system where the input signals are floating with respect to the power supply. it sets a vo ltage that is approximately 2.8v lower t han the positive supply. in most of the applications, in lo, rf lo and com pins are tied to the same point, so that the common mode voltage can be removed from the reference system and the converter. within the ic, analog common is tied to an n-channel fe t that can sink approximatel y 30ma of current to hold the voltage 2.8v below the positive supp ly (when a load is trying to pull t he common voltage toward the positive supply). however, there is only 10 a of source current, so com voltage is easily tied to a more negative voltage with respect to the positive supply.
m7206 cmos ic unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r502-q37.a ? detailed description(cont.) test the test pin serves two functions. within ic it is c oupled to the internally generated digital supply through an nmos. thus it can be used as the negative supply for external ly generated segment drivers such as decimal points or any other presentation the user may want to include on the lcd displa y. the second function is a ?lamp test?. when test is pulled high(to v+)all segment will be turned on and output should be ?1888?. component value selection integrating resistor both the buffer amplifier and the integr ator have an output stage with 100 a of quiescent current. they can supply 4 a of drive current with negligible nonlinearity. the integr ating resistor should be large enough to remain in this very linear region over the input voltage range, but sma ll enough that undue leakage requirements are not placed on the pc board. for 2v full scale, 470k ? is near optimum and similarly a 47k ? for a 200mv scale. integrating capacitor the integrating capacitor should give the maximum voltage swing that ensures tolerance buildup will not saturate the integrator swing (approximately. 0.3v from either supply). when the anal og common is used as a reference, a nominal +2v full-scale integrator swing is fine. for three readings /second (48 khz clock) nominal values for clnt are 0.22 f and 0.10 f, respectively. of course, if different oscilla tor frequencies are used, these values should be changed in inverse proportion to maintain the same output swing. an additional requirement of the integr ating capacitor is that it must have a low dielectric absorption to prevent roll-over errors. while other types of capacitors are adequate for this application, polypropylene capacitors give the best choice. auto-zero capacitor the size of the auto-zero capacitor has some influence on the noise of the system. for 200mv full scale where noise is very important, a 0.47 f capacitor is recommended. on the 2v scale, a 0.047 f capacitor increases the speed of recovery from overload and is adequate for noise on this scale. oscillator components for all ranges of frequency a 100k ? resistor is recommended and the capa citor is selected from the equation: f0.45/rc ? for 48khz clock(3 reading/sec), c=100pf. reference capacitor a 0.1 f capacitor gives good results in most applications. however, where a large common mode voltage exists and a 200mv scale is used, a larger value is r equired to prevent roll-over error. generally 1 f will hold the roll-over error to 0.5 count in this instance. reference voltage the analog input required to generate full scale output (2000 counts) is: in ref v2v ? 0. a compensating offset voltage c an be applied between com and in lo and the voltage of being measured is connected between com and in hi. utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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