UCSP, Micropower, Single-Supply, 10V, Rail-to-Rail I/O Op Ampsa)RAIL-TO-RAILb)RAIL-TO-RAILINPUT/OUTPUT VOLTAGE RANGEINPUT/OUTPUT VOLTAGE RANGE(VDD = 3V)(VDD = 2V) MAX4162-34 MAX4162-35 2V 3V IN IN 1V/div 0.667V/div 0 0 2V 3V OUT OUT 1V/div 0.667V/div 0 0 200µs/div 200µs/div V V DD = 3V, VP-P = 3V, f = 1kHz, RL = 10kΩ DD = 2V, VP-P = 2V, f = 1kHz, RL = 10kΩ Figure 1. Rail-to-Rail I/O: a) VDD = 3V; b) VDD = 2V suffer from midswing common-mode-rejection degrada- tion or crossover nonlinearity often encountered in other LARGE CAPACITIVE-LOAD DRIVE rail-to-rail op amps. Extremely low, 1.0pA input bias cur- MAX4162-36 rent makes these devices ideal for applications such as 500mV pH probes, electrometers, and ionization detectors. IN They are also protected against phase reversal (inferred 200mV/div from CMRR test) and latchup for input signals extending MAX4162/MAX4163/MAX4164 0 beyond the supply rails. The output stage achieves a lower output impedance than traditional rail-to-rail out- 500mV put stages, providing an output voltage range that typi- cally swings within 150mV of the supply rails for 1mA OUT 200mV/div loads. This architecture also maintains high open-loop 0 gain and output swing while driving substantial loads. Output Loading and Stability 5µs/div These devices drive 1mA loads to within 150mV of the AV = 1, CL = 1µF, RL = 100kΩ supply rails while consuming only 25µA of quiescent current. Internal compensation allows these amplifiers to remain unity-gain stable while driving any capacitive Figure 2. Large Capacitive-Load Drive load (Figure 2). Internal Charge Pump__________Applications Information An internal charge pump provides two internal supplies typically 2V beyond each rail. These internal rails allow Rail-to-Rail Inputs and Outputs the MAX4162/MAX4163/MAX4164 to achieve true rail- The MAX4162/MAX4163/MAX4164 input common-mode to-rail inputs and outputs, while providing excellent range extends 250mV beyond each of the supply rails, common-mode rejection, power-supply rejection ratios, providing a substantial increase in dynamic range over and gain linearity. other op amps (even many of those referred to as rail-to- rail). Although the minimum operating voltage is speci- These charge pumps require no external components, fied at 2.5V, the devices typically provide full rail-to-rail and in most applications are entirely transparent to the operation below 2.0V (Figure 1). These amplifiers do not user. Two characteristics may be visible to the user, depending on the application: 10______________________________________________________________________________________
