Application Information

Low Supply Voltage and Low Power Consumption

The TP600X family of operational amplifiers can operate with power supply voltages from 2.1 V to 6.0 V. Each amplifier draws only

8

0 μA quiescent current. The low supply voltage capability and low supply current are ideal for portable applications demanding high

capacitive load driving capability and stable wide bandwidth. The TP600X family is optimized for wide bandwidth low power

applications. They have an industry leading high GBWP to power ratio and are unity gain stable for any capacitive load. When the

load capacitance increases, the increased capacitance at the output pushed the non-dominant pole to lower frequency in the open

loop frequency response, lowering the phase and gain margin. Higher gain configurations tend to have better capacitive drive

capability than lower gain configurations due to lower closed loop bandwidth and hence higher phase margin.

Ground Sensing and Rail to Rail Output

The TP600X family has excellent output drive capability, delivering over 100 mA of output drive current. The output stage is a rail-to-

rail topology that is capable of swinging to within 10mV of either rail. Since the inputs can go 300 mV beyond either rail, the op-amp

can easily perform ‘true ground’ sensing.

The maximum output current is a function of total supply voltage. As the supply voltage to the amplifier increases, the output current

capability also increases. Attention must be paid to keep the junction temperature of the IC below 150°C when the output is in

continuous short-circuit. The output of the amplifier has reverse-biased ESD diodes connected to each supply. The output should not

be forced more than 0.5V beyond either supply, otherwise current will flow through these diodes.

Driving Large Capacitive Load

The TP600X

family of OPA is designed to drive large capacitive loads. Refer to Typical Performance Characteristics for “Phase Margin

vs. Load Capacitance”. As always, larger load capacitance decreases overall phase margin in a feedback system where internal

frequency compensation is utilized. As the load capacitance increases, the feedback loop’s phase margin decreases, and the

closed-loop bandwidth is reduced. This produces gain peaking in the frequency response, with overshoot and ringing in output step

response. The unity-gain buffer (G = +1V/V) is the most sensitive to large capacitive loads.

When driving large capacitive loads with the TP600X OPA family (e.g., > 200 pF when G = +1V/V), a small series resistor at the

output (RISO in Figure 3) improves the feedback loop’s phase margin and stability by making the output load resistive at higher

frequencies.

Vin

Vout

Cload

Riso