TPS65100PWPR datasheet(16/32 Pages) TI

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Load Step

Compensation

VIN

COMP

15 k

Ω

1 nF

fz +

TPS65100, TPS65101

TPS65105

SLVS496C – SEPTEMBER 2003 – REVISED APRIL 2006

Figure 16. Load Step Caused By A Too Large Feedforward Capacitor Value

The regulator loop can be compensated by adjusting the external components connected to the COMP pin. The

COMP pin is connected to the output of the internal transconductance error amplifier. A typical compensation

scheme is shown in Figure 17.

Figure 17. Compensation Network

The compensation capacitor CC adjusts the low frequency gain and the resistor value adjusts the high frequency

gain. The formula below calculates at what frequency the resistor increases the high frequency gain.

Lower input voltages require a higher gain and therefore a lower compensation capacitor value. A good start is

CC = 1 nF for a 3.3-V input and CC = 2.2 nF for a 5-V input. If the device operates over the entire input voltage

range from 2.7 V to 5.8 V, a large compensation capacitor up to 10 nF is recommended. Figure 18 shows the

load transient with a larger compensation capacitor, and Figure 19 shows a smaller compensation capacitor.

Figure 18. Cc = 4.7 nF

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TPS65100PWPR Datasheet(PDF) 16 Page - Texas Instruments