UNISONIC TECHNOLOGIES CO., LTD M7206 CMOS IC 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. Compared 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 astable 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 Lead Free Halogen Free M7206L-QL1-Y M7206G-QL1-Y www.unisonic.com.tw Copyright © 2013 Unisonic Technologies Co., Ltd Package Packing LQFP-44 Tray 1 of 8 QW-R502-Q37.A M7206 CMOS IC PIN CONFIGURATIONS PIN DESCRIPTION PIN NAME TYPE 1 BZ O 2 BZEN I 3 4 TEST OSC3 - 5 HOLD O OSC2 OSC1 V+ A1~G1 A2~G2 A3~G3 P O O O 26 AB4 O 27 28 33 34 35 36 37 38 39 40 41 42 43 44 POL BP LOWB VINT BUFF A/Z IN LO IN HI COMMON C-REFC-REF+ REF LO REF HI O O O P I I O I I 6 7 8 9～15 16～21、32 22~25, 29~31 PIN DESCRIPTION Piezo buzzer output. Whenever BZEN is connected to V+ and differential inputs are tied together, BZ will generate a 5KHz sound output. Buzzer control slave input. This pin is internally pulled-down to TEST.See BZ Digital GND. Pull high to V+ all LCD segments will be activated. Crystal oscillator connection. (RC) Hold control pin. When it receives a negative mud pulse, display hold; Receive again then function disabled. Crystal oscillator connection. (output) Crystal oscillator connection. (input) Positive supply voltage LCD segment drive (unit) LCD segment drive (decade) LCD segment drive (hundred) LCD segment drive (thousand). When the readout exceeds 1999, AB4 drive the segment of thousand to display ‘1’ for showing excess. LCD segment drive. (minus ‘-‘) LCD common drive. LCD segment drive. (low battery) Negative supply voltage. Connecting to battery negative terminal. Integrator output. Integration register connection Auto-zero capacitor connection Analog low input signal Analog high input signal Set the common-mode voltage for the system Negative capacitor connection for on-chip A/D converter Positive capacitor connection for on-chip A/D converter Low differential reference input connection. High differential reference input connection UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 8 QW-R502-Q37.A M7206 CMOS IC PIN FIGURE PIN COORDINATES PIN Name 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 BZ BZEN TEST OSC3 HOLD OSC2 OSC1 V+ D1 C1 B1 A1 F1 G1 E1 D2 C2 B2 A2 F2 E2 D3 B3 Coordinate X Y 2135 325 2135 475 2135 625 2135 885 2135 1035 2135 1185 2135 1335 2135 1550 2135 1710 2135 1860 2135 2010 1970 2115 1820 2115 1670 2115 1520 2115 1370 2115 1220 2115 1070 2115 920 2115 770 2115 620 2115 470 2115 320 2115 UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw PIN Name 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 F3 E3 AB4 POL BP HLDO BPG3 A3 C3 G2 LB VINT BUF AZ IN LO IN HI COM CREFCREF+ RF LO RF HI Coordinate X Y 130 2115 95 1965 95 1815 95 1665 95 1515 95 1365 95 1165 95 1015 95 865 95 715 95 565 95 415 95 265 570 95 725 95 880 95 1030 95 1350 95 1510 95 1670 95 1820 95 1970 95 2120 95 3 of 8 QW-R502-Q37.A M7206 CMOS IC BLOCK DIAGRAM UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 8 QW-R502-Q37.A M7206 CMOS IC ABSOLUTE MAXIMUM RATING (unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT Power Supply Voltage（V+～V-） VCC 12 V Analog input voltage VIANG V+~VV Reference Input Voltage VIREF V+~VV Operating Temperature Range TOPR 0 ~ 70 °C Storage Temperature TSTG -65 ~ +150 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. ELECTRICAL CHARACTERISTICS (VCC＝9V, TA=25°C, unless otherwise specified) PARAMETER VCC Range Supply Current(Does not conclude COMMON current ) SYMBOL VCC ICC TEST CONDITIONS TYP 9 MAX UNIT V 0.6 1.2 mA -000.0 ±000.0 +000.0 999 999/ 1000 1001 -1 ± 0.2 +1 Counts -1 6.6 ± 0.2 1 6.9 +1 10 7.2 Counts PA V 2.80 3.00 3.20 V VIN=0V DC characteristics Zero Input Reading VIN=0V, full-scale=200mV Ratio metric Reading VIN=VREF, VREF=100mV Linearity (MAX. deviation form best straight line fit) Roll-over Error Input Leakage Current Low battery flag Analog Common Voltage ( with respect to V+) full-scale=200.0mV or full-scale=2.0V -VIN=+VIN ~ 200mV VIH=0V V+ to V25kΩ Between Common and Positive Supply UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN Digital Reading Digital Reading 5 of 8 QW-R502-Q37.A M7206 CMOS IC TYPICAL APPLICATIONS CIRCUITS Figure 1 UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 8 QW-R502-Q37.A M7206 CMOS IC Detailed Description Analog Section The measurement cycle of analog section 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 the reference voltage. Third, a feedback loop is closed around the system to charge the auto-zero capacitor CAZ to compensate for offset voltages in the buffer amplifier, integrator and comparator. Since the comparator is included in the loop, the A-Z accuracy is limited only by the noise of the system. In any case, the offset referred to the input is less than 10uV. Signal Integrate Phase During signal integrate the auto-zero loops are opened, the internal short is removed, and the internal inputs high and low are connected to the external pins. The converter then integrates the differential voltage between INHI and INLO for a fixed time. This differential voltage can be within a wide common mode range: up to 1V from either supply. On the other hand, if the input signal has no return with respect to the converter power supply, IN LO can be tied to analog COMMON to establish the correct common mode voltage. At the end of this phase, 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 reference 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 input signal. Specifically the digital reading displayed is: DISPLAY COUNT=1000(VIN/VREF) Differential Input The input can accept differential voltages anywhere within the common mode range of the input amplifier, or specifically from 0.5V below the positive supply to 1V above the negative supply. In this range, the system has a CMRR of 86dB typical. However, we must make sure that the integrator output 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 integrator positive when most of its swing has been used up by the positive common mod e voltage. For these critical applications the integrator output swing can 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 anywhere within the power supply voltage 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 voltage will give a roll-over error. However, by selecting the reference capacitor such that it is large enough in comparison to the stray capacitance, 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 voltage that is approximately 2.8V lower than 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 FET that can sink approximately 30mA of current to hold the voltage 2.8V below the positive supply (when a load is trying to pull the common voltage toward the positive supply). However, there is only 10μA of source current, so COM voltage is easily tied to a more negative voltage with respect to the positive supply. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 8 QW-R502-Q37.A M7206 CMOS IC Detailed Description(Cont.) TEST The TEST pin serves two functions. Within IC it is coupled to the internally generated digital supply through an NMOS. Thus it can be used as the negative supply for externally generated segment drivers such as decimal points or any other presentation the user may want to include on the LCD display. 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 integrator have an output stage with 100μA of quiescent current. They can supply 4μA of drive current with negligible nonlinearity. The integrating resistor should be large enough to remain in this very linear region over the input voltage range, but small enough that undue leakage requirements are not placed on the PC board. For 2V full scale, 470kΩ is near optimum and similarly a 47kΩ 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 analog 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 0.22μF and 0.10μF, respectively. Of course, if different oscillator frequencies are used, these values should be changed in inverse proportion to maintain the same output swing. An additional requirement of the integrating 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 0.47μF capacitor is recommended. On the 2V scale, a 0.047μF capacitor increases the speed of recovery from overload and is adequate for noise on this scale. Oscillator Components For all ranges of frequency a 100kΩ resistor is recommended and the capacitor is selected from the equation: f 0.45 / RC For 48kHz clock(3 Reading/sec), C=100pF. Reference Capacitor A 0.1μF 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 required to prevent roll-over error. Generally 1μF 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: VIN 2VREF . Thus, for the 200mV and 2V scale, VREF should equal 100mV and 1V, respectively. However, in some applications the full-scale input voltage may be other than 200mV or 2V, but 600mV. For example, the reference voltage should be set to 300mV and the input signal can be used directly without being divided. The differential reference can be used during the measurement of resistor by the ratio metric method and when a digital reading of zero is desired for VIN≠0. A compensating offset voltage can 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. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 8 QW-R502-Q37.A