LM6172

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SNOS792D – MAY 1999 – REVISED MARCH 2013

Another possible source of overshoot and undershoot comes from capacitive load at the output. Please see

DRIVING CAPACITIVE LOADS for more detail.

DRIVING CAPACITIVE LOADS

Amplifiers driving capacitive loads can oscillate or have ringing at the output. To eliminate oscillation or reduce

ringing, an isolation resistor can be placed as shown in Figure 43. The combination of the isolation resistor and

the load capacitor forms a pole to increase stability by adding more phase margin to the overall system. The

desired performance depends on the value of the isolation resistor; the bigger the isolation resistor, the more

damped (slow) the pulse response becomes. For LM6172, a 50

Ω isolation resistor is recommended for initial

evaluation.

Figure 43. Isolation Resistor Used to Drive Capacitive Load

Figure 44. The LM6172 Driving a 510pF Load with a 30

Ω Isolation Resistor

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