ISL68229IRAZ datasheet(30/107 Pages) RENESAS

30 / 107 page

ISL68229, ISL68239

6. Fault Monitoring and Protection

R16DS0006EU0101 Rev.1.01

Page 30 of 106

Jul 21, 2022

6.3

Output Overcurrent Protection

The ISL68229 and ISL68239 offer a comprehensive overcurrent protection scheme that monitors the total output

current, peak phase current, and the valley phase current. The scheme allows you to eliminate inductor saturation

and limit the total output current. The ISL68229 and ISL68239 support shutdown and retry response types for OC

faults. The response configuration applies to all output current fault mechanisms such as phase peak overcurrent

and total output overcurrent.

Figure 20 shows the block diagram of the output overcurrent protection scheme.

Phases are protected from both overcurrent and undercurrent using a pulse-by-pulse scheme that acts instantly

on a PWM signal if a detected phase current reaches its threshold. Thresholds for overcurrent and undercurrent

allow you to precisely limit phase currents so the inductors never saturate. Phase current limiting behavior can be

configured to either shut down the device after a user-determined number of consecutive events or continue

indefinitely. If configured to continue indefinitely, the converter behaves much like a current source. Figures 21

and 22 show per-phase current limiting when the device is configured to shut down after a finite number of

consecutive events.

In addition to phase based current limiting, the ISL68229 and ISL68239 support total output current limits that

have user-adjustable response delay. The two sum current limits, fast and slow, allow you to permit high

maximum output current for a shorter period of time and lower output current for a longer period. The response

delay for the limiting mechanisms is also adjustable. These mechanisms do not restrict the maximum output

current until the current exceeds a threshold for the response delay time. For example, suppose the device is

configured with a Fast Sum OC limit of 350A, a response delay of 50µs, and a shutdown response type. Next,

suppose a 400A load is placed on the regulator. 400A is supplied to the load for 50µs, and the device then shuts

down as shown in Figure 23 on page 31.

Figure 20. OCP Functional Diagram

Figure 21. Peak OC Operation

Figure 22. Peak UC Operation

ISL68229IRAZ Datasheet(PDF) 30 Page - Renesas Technology Corp