ES5107 3 1/2 DIGIT A/D CONVERTER W/LED I、GENERL DESCRIPTION The ES5107 is a low power CMOS 3 1/2 digit A/D converter With LED display drivers. The single chip ES5107 provides all the necessary active devices which contain the internal clock. voltage reference. seven-segment decoders, LED display drivers. The improved internal zener reference voltage circuit gives the analog common a small temperature coefficient of 60 ppm/℃ typically. The high accuracy characteristics of the ES5107 perform very low linearity error and rollover error. The high input impedance(>1012Ω) and low input leakage current (1pA typical)give the ES5107 a good application in the field of high impedance circuit measurement. The differential input and reference are suitable for measuring bridge transducer or ohms by using ratio-metric method. The dual slope conversion technique makes the ES5107 a good normal mode and common mode rejection ratio. With a suitable oscillator frequency. the ES5107 has a high rejection of 50Hz, 60Hz and 400Hz line frequency noise. With a set of LED display and a few resistors and capacitors ES5107 can be built as a high performance panel meter. Existing ICL7107 based systems may be upgraded without changing external passive component values. II、FEATURES *Guaranteed zero reading with zero input. *Low input leakage current (1pA typical) *Internal Reference with low temperature drift (60ppm/℃ typical) 1 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED *Low noise(15µ Vp-p typical) *Direct LED display drive-no external components required *Differential input and voltage reference *Internal clock circuit III、APPLICATTONS *Digital panel meters *Digital multimeters *Thermometers *Capacitance meters *pH meters *Photometers 2 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED IV、PIN ASSIGNMENT 3 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED V、BLOCK DIAGRAM 4 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED VI、ABSOLUTE MAXIMUM RATINGS Characteristic Rating Supply Voltage V+ +6V V- -6V Analog Input Voltage(either input) V+ to V- Reference Input Voltage(either input) V+ to V- Clock Input GND to V+ Power Dissipation(plastic package) 800 mW Operating Temperatuer 0℃ to +70℃ Storage Temperature -65℃ to +160℃ Lead Temperature(Soldering, 10 sec) 270℃ 5 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED VII、ELECTRICAL CHARACTERISTICS At V+ = +5V，V- = -5V，feocx = 48KHz，TA = 25℃ Characteristic Zero Input Reading Test Conditions VIN = OV Full Scale = 200mV Ratio-metric VIN = VREF Reading VREF = 100mV Linearity Full Scale = 200mV or 2V Rollover Error -VIN = +VIN ≅ 200mV Common Mode VCM = ±1V,VIN = OV Rejection Ratio Full Scale = 200mV Noise (PK-PK Value not VIN = OV exceeded 95% of time) Full Scale = 200mV Input Leakage VIN = OV Current Analog COMMON 25KΩ between Voltage Common and V+ Analog COMMON 25KΩ between Temperature Common and V+ Coefficient O℃≤TA≤70℃ Scale Factor Temperature Coefficient VIN = 199mV O℃≤TA≤70℃Ext. Ref. Oppm/℃ Zero Reading Drift VIN = OV O℃≤TA≤70℃ Segment Sinking Current (except Pin 19) (include Pin 19) V+ Supply Current (not include LED current) V- Supply Current V+ = 5V Segment Voltage = 3V VIN = OV 6 Min -000.0 Typ. ±000.0 Max +000.0 Units Digital Reading Digital Reading Counts 999 999/1000 1000 -1 ±0.2 +1 -1 - ±0.2 50 +1 - Counts - 15 - µVP-P - 1 10 pA 2.8 3.0 3.2 V - 60 75 ppm/℃ - 60 75 ppm/℃ - 0.2 1 µV/℃ 5 10 8 16 - mA mA - 0.5 0.65 mA - 0.5 0.65 mA µV/V ES5107 3 1/2 DIGIT A/D CONVERTER W/LED 7 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED D、APPLICATION CIRCUITS A、Internal Reference:The analog COMMON voltage is used as reference voltage. Values here are for 2.0000V full-scale. 8 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED B、External Band-Gap Reference: A band-gap reference of 1.2V type is used to set up a high temperature stability voltage reference. 9 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED C、Zener Diode Reference: A low TC zener diode is used to set up the low temperature drift reference voltage. 10 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED D、Measuring Ratio-metric Values of Quad Load Cell. 11 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED X、PCB LAYOUT A、Board Back 12 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED B、Board Component Side. 13 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED XI、NOTES FOR APPLICATION A、Analog COMMON The COMMON pin is used to set the common-mode voltage for the system in which the input signals are floating with respect to the power supply of the ES5107. In all most of the applications, IN LO, REF LO and COMMON Pins are tied to the same point, so that the common mode voltage can be removed from the reference system and the converter. In some applications, IN LO may not at the same point with COMMON and thus a common mode voltage exists in the system the high CMRR(86dB typical )of the ES5107 can take care of this common mode voltage. Nevertheless, it should be care to prevent the output of the integrator from saturation. The COMMON pin is also used as a voltage reference. It sets a voltage, which is around 2.9 volts more negative than the positive supply. The COMMON voltage of ES5107 has a 0.001%/% voltage coefficient and a low output impedance of 15Ω typical. The analog COMMON is tied internally to an N channel FET capable of sinking 30mA. This FET will hold the COMMON voltage at 2.9 volts when an external load attempt to pull the COMMON voltage toward the positive supply. The source current of COMMON is only 10µA, so it is easy to pull COMMON voltage to a more negative voltage with respect to the positive supply. 14 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED When the total supply voltage is large enough to cause the zener to regulate(>7V), the COMMON voltage will have a low temperature coefficient typically less than 60 ppm/℃ This voltage can be used to generate the ES5107 reference voltage and an external voltage reference will be unnecessary in most cases. B、Reference Voltage For a 1000 counts reading. the input signal must be equal to the reference voltage. So for a 2000 counts full scale reading, it requires the input signal be twice the reference voltage. Thus for the 200.0mV and 2.000V full scale, the reference voltage should equal 100.0mV and 1.000V 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 COMMON and IN LO and the voltage of being measured is connected bet ween COMMON and IN HI. C、System Timing The oscillator frequency is divided by four prior to clocking the internal decade counters. The signal integrate takes a fixed 1000 counts time period which is equal to 4000 clock pulses. 15 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED To make a maximum rejection of line frequency (60 HZ or 50HZ) noise pickcup, the signal integrate period should be a multiple of the line frequency period. For 60Hz noise rejection, oscillator frequencies of 120KHz, 80Khz, 60KHz, 48KHz, 40KHz etc. should be selected. For 50Hz rejection, oscillator frequencies of 100KKz , 40KHz, etc. would be suitable. For all ranges of frequency Rosc should be 100KΩ Cosc is selected from the approximate equation f=0.45/RC For 48KHz clock (3 readings/second), Cosc = 100pF. D、Integrating Resistor The input buffer amplifier and integrator both have a class A output stage with 100µA of quiescent current and can supply 20µA drive currents with negligible linearity errors. The integrating resistor should be chosen to remain in the output stage linear drive region. It should be noticed that the integrating resistor should not be so large such that the leakage currents of printed circuit board will induce errors. For a 200mV full-scale the recommended integrating resistor value is 47KΩ and for 2V full scale is 470KΩ. E、Integrating Capacitor The integrating capacitor should be selected to maximize integrator output voltage swing without causing output saturation. If the analog COMMON is used as voltage reference a ±2V full-scale integrator output swing is satisfactory For 3 readings/second)48Khz clock)a 0.22µF value of CINT is suggested. When different oscillator frequencies are used 16 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED CINT must be changed in inverse proportion to maintain the nominal ±2V integrator swing. The integrating capacitor should have low dielectric absorption to minimize roll-over error. An inexpensive polypropylene capacitor will work well. F、Auto-Zero Capacitor The auto-zero capacitor size has some influence on system noise. A 0.47µF capacitor is recommended for 200mV full scale where noise is very important. A 0.047µF capacitor is adequate for 2V full scale applications. A mylar type dielectric capacitor is adequate. G、Reference Voltage Capacitor When IN LO is tied to analog COMMON, a 0.1µF capacitor is adequate to be the reference capacitor. If a large common mode voltage exists and the application require a 200mV full scale a larger value is required to prevent roll over error A1.0µF capacitor will hold the roll-over error to 0.5 count. H、Test The TEST pin is tied to the internal negative logic supply through a 500Ω resistor. When TEST is pulled high all segments will be turned on and the display should read -1888. 17 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED XII、PHYSICAL DIMENSION 18 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED ㆒、ES5170Q PIN CONFIGURATION 19 ES5107 3 1/2 DIGIT A/D CONVERTER W/LED ㆓、ES5107Q-PACKAGE 20