TLC4501, TLC4501A, TLC4502, TLC4502A

FAMILY OF SELF-CALIBRATING (Self-Cal

)

PRECISION CMOS RAIL-TO-RAIL OUTPUT OPERATIONAL AMPLIFIERS

SLOS221B – MAY 1998 – REVISED APRIL 2001

20

POST OFFICE BOX 655303

APPLICATION INFORMATION

remain in the linear mode with an input common-mode voltage of 0.

diodes are not needed, no large input currents result from large differential input voltage. Protection should

be provided to prevent the input voltages from going negative more than – 0.3 V at 25

°C. An input clamp

diode with a resistor to the device input terminal can be used for this purpose.

used from the output of the amplifier to ground. This increases the class-A bias current and prevents

crossover distortion. Where the load is directly coupled, for example in dc applications, there is no crossover

distortion.

Values of 500 pF can be accommodated using the worst-case noninverting unity-gain connection. Resistive

isolation should be considered when larger load capacitance must be driven by the amplifier.

The following typical application circuits emphasize operation on only a single power supply. When

complementary power supplies are available, the TLC4502 can be used in all of the standard operational

TLE2426) allows operation above and below this value in a single-supply system. Many application circuits

shown take advantage of the wide common-mode input-voltage range of the TLC4502, which includes ground.

In most cases, input biasing is not required and input voltages that range to ground can easily be

accommodated.

description of calibration procedure

To achieve high dc gain, large bandwidth, high CMRR and PSRR, as well as good output drive capability, the

TLC4502 is built around a 3-stage topology: two gain stages, one rail-to-rail, and a class-AB output stage. A

nested Miller topology is used for frequency compensation.

During the calibration procedure, the operational amplifier is removed from the signal path and both inputs are

tied to GND. Figure 35 shows a block diagram of the amplifier during calibration mode.