ISL68233IRAZ datasheet(24/103 Pages) RENESAS

24 / 103 page

ISL68222, ISL68233

4. Operating the Device

R16DS0036EU0100 Rev.1.00

Page 24 of 102

Oct.1.20

4.10.4 L/DCR or ESL/RSEN Matching

Assuming the compensator design is correct, Figure 14 shows the expected load transient response waveforms if

L/DCR or ESL/RSEN matches the R-C time constant for a droop application. When the load current IOUT has a

square change, the output voltage VOUT also has a square response, except for the potential overshoot at load

release. However, there is always some uncertainty in the true parameter values involved in the time constant

matching, so fine-tuning is generally required.

If the R-C time constant is too large or too small, VC(t) does not accurately represent real-time IOUT(t) and

worsens the transient response. Figure 15 shows the load transient response when the R-C time constant is too

small. In this condition, VOUT sags excessively on load insertion and can create a system failure or early

overcurrent trip.

Figure 16 shows the transient response when the R-C time constant is too large. VOUT is sluggish in drooping to

its final value. Use these general guides if fine-tuning is needed.

Figure 14. Desired Load Transient Response Waveforms

Figure 15. Load Transient Response when R-C Time Constant is Too Small

Figure 16. Load Transient Response when R-C Time Constant is Too Large

IOUT

VOUT

IOUT

VOUT

IOUT

VOUT

ISL68233IRAZ Datasheet(PDF) 24 Page - Renesas Technology Corp