LV2622L-S08-R datasheet(5/8 Pages) UTC

5 / 8 page

LV2622

Preliminary

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

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www.unisonic.com.tw

QW-R102-045.a

APPLICATION NOTES

Driving a Capacitive Load

The UTC LV2622 can directly drive 1000pF in unity-gain without oscillation. The unity-gain follower (buffer) is the

most sensitive configuration to capacitive loading.

When the amplifier is configured in this manner, capacitive

loading directly on the output will decrease the device’s phase margin leading to high frequency ringing

or oscillations. It is recommended that an isolation resistor (RISO) is placed in series with the output of the

amplifier when the greater capacitive load is required. The circuit is shown in Figure 1. The RISO and the load

capacitor CL form a zero to increase stability, but this method results in a loss of gain accuracy for RISO dividing the

voltage with RLOAD.

The circuit in Figure 2 provides DC accuracy and AC stability. To increase the DC accuracy, RF should be

connected between the inverting input and the output. To preserve the phase margin in the overall feedback loop, CF

is required and can compensate the loss of phase margin together with RIso by feeding the high frequency

component of the output signal back to the amplifier’s inverting input

UTC LV2622

Figure 2. Indirectly Driving Heavy Capacitive Load with DC Accuracy

VIN

RISO

VOUT

1/2

For no-buffer configuration, there are two others ways to increase the phase margin: (a) by increasing the

amplifier’s gain or (b) by placing a capacitor in parallel with the feedback resistor to counteract the parasitic

capacitance associated with inverting node.

LV2622L-S08-R Datenblatt(PDF) 5 Page - Unisonic Technologies