AD712

Rev. G | Page 16 of 20

200ns

500mV

PD711 BUFF

–10V ADC IN

1mV

100

10

0%

90

Figure 44. ADC Input Unity Gain Buffer Recovery Times, −10 V ADC IN

200ns

500mV

PD711 BUFF

–5V ADC IN

1mV

100

10

0%

90

Figure 45. ADC Input Unity Gain Buffer Recovery Times, −5 V ADC IN

DRIVING A LARGE CAPACITIVE LOAD

The circuit in Figure 46 uses a 100 Ω isolation resistor that

enables the amplifier to drive capacitive loads exceeding

1500 pF; the resistor effectively isolates the high frequency

feedback from the load and stabilizes the circuit. Low frequency

feedback is returned to the amplifier summing junction via the

low-pass filter formed by the 100 Ω series resistor and the Load

this connection.

1/2

AD712

0.1µF

0.1µF

INPUT

2kΩ

1500pF

10kΩ

1500pF

20Ω

1000pF

C1

R1

4.99kΩ

4.99kΩ

30pF

OUTPUT

100Ω

+ –

–

+

TYPICAL CAPACITANCE

LIMIT FOR VARIOUS

LOAD RESISTORS

Figure 46. Circuit for Driving a Large Capacitive Load

5V

1µs

100

10

0%

90