CS5308GDWR28 datasheet(23/31 Pages) ONSEMI

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CS5308

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the RCSn • CCSn network to provide a “square−wave” at the

VDRP output pin with maximum rise time and minimal

overshoot as shown in Figure 21.

Figure 19. VDRP Tuning Waveforms. The RC Time

Constant of the Current Sense Network Is Too Long

(Slow): VDRP and VOUT Respond Too Slowly.

Figure 20. VDRP Tuning Waveforms. The RC Time

Constant of the Current Sense Network Is Too Short

(Fast): VDRP and VOUT Both Overshoot.

Figure 21. VDRP Tuning Waveforms. The RC Time

Constant of the Current Sense Network Is Optimal:

VDRP and VOUT Respond to the Load Current Quickly

Without Overshooting.

8. Error Amplifier Tuning

After the steady−state (static) AVP has been set and the

current sense network has been optimized the Error

Amplifier must be tuned. Basically, the gain of the Error

Amplifier should be adjusted to provide an acceptable

transient response by increasing or decreasing the Error

Amplifier’s feedback capacitor (CAMP in the Applications

Diagram). The bandwidth of the control loop will vary

directly with the gain of the error amplifier.

Figure 22. The Value of CAMP Is Too High and the

Loop Gain/Bandwidth Too Low. COMP Slews Too

Slowly Which Results in Overshoot in VOUT.

If CAMP is too large the loop gain/bandwidth will be low,

the COMP pin will slew too slowly, and the output voltage

will overshoot as shown in Figure 22. On the other hand, if

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