The MAX138CPL+ is a 3.5 digit analogue to digital converter (ADC) with reference, charge pump and onboard LCD display drivers in 40 pin DIP package. The charge pump inverter allows the device to measure both positive and negative input voltages while operating from single power supply voltages from 2.5V to 7V. The operating circuits of MAX138 are similar to those of ICL7136 except the MAX138 has an internal oscillator and an external charge pump capacitor connected to pins 38 and 40. It is used in 5V powered panel meters, 3V powered DMMs and digital thermometers.
V+ current of 200μA at TA = 25°C
Operating temperature range from 0°C to 70°C
Charge pump voltage inverter generates a negative supply voltages
Internal bandgap reference
Peak to peak segment drive voltage of 5V and test pin voltage of 5V with respect to V+
±000.0 digital reading (zero input reading) at TA = 25°C
999/1000 digital reading (ratiometric reading) at TA = 25°C
Rollover error of ±0.2counts at TA = 25°C and linearity of ±0.2counts
CMRR of 50μV/V and noise of 15μV
±20ppm/°C temperature coefficient of analogue common with respect to positive supply
