AD8610/AD8620
Driving Large Capacitive Loads
The AD8610/AD8620 have excellent capacitive load driving
capability and can safely drive up to 10 nF when operating with
±5 V supply. Figure 44 and Figure 45 compare the AD8610/
AD8620 against the OPA627 in the noninverting gain configu
ration driving a 10 kΩ resistor and 10,000 pF capacitor placed
in parallel on its output, with a square wave input set to a frequency
of 200 kHz. The AD8610/AD8620 have much less ringing than
the OPA627 with heavy capacitive loads.
VS = ±5V
RL = 10kΩ
CL = 10,000pF
TIME (2µs/DIV)
Figure 44. OPA627 Driving CL = 10,000 pF
VS = ±5V
RL = 10kΩ
CL = 10,000pF
+5V
3
7
VIN = 50mV 2
4
–5V
2µF
2kΩ
2kΩ
Figure 46. Capacitive Load Drive Test Circuit
VS = ±5V
RL = 10kΩ
CL = 2µF
TIME (20µs/DIV)
Figure 47. OPA627 Capacitive Load Drive, AV = +2
TIME (2µs/DIV)
Figure 45. AD8610/AD8620 Driving CL = 10,000 pF
The AD8610/AD8620 can drive much larger capacitances
without any external compensation. Although the AD8610/
AD8620 are stable with very large capacitive loads, remember
that this capacitive loading limits the bandwidth of the amplifier.
Heavy capacitive loads also increase the amount of overshoot
and ringing at the output. Figure 47 and Figure 48 show the
AD8610/AD8620 and the OPA627 in a noninverting gain of +2
driving 2 μF of capacitance load. The ringing on the OPA627 is
much larger in magnitude and continues 10 times longer than
the AD8610/AD8620.
VS = ±5V
RL = 10kΩ
CL = 2µF
TIME (20µs/DIV)
Figure 48. AD8610/AD8620 Capacitive Load Drive, AV = +2
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