ISL68147IRAZ datasheet(18/47 Pages) RENESAS

18 / 47 page

ISL68147

FN8880 Rev.2.00

Page 18 of 47

Jul 14, 2017

Example OCP_Fast and OCP_Slow waveforms are shown in

Figures 20 and 21.

Smart Power Stage OC Fault Detect

Intersil Smart Power Stage (SPS) devices will output a large

signal on their IMON lines if the peak current exceeds their

preprogrammed threshold. (For more details about this

functionality, refer to the relevant SPS datasheet.) The ISL68147

is equipped to detect this fault flag and immediately shut down.

This detector is enabled on the GUI Overcurrent Fault setup

screen.

This feature functions by detecting signals that exceed the

current sense ADC full scale range. If this detector is disabled

while using an Intersil SPS, the SPS Fault# signal must be

connected to the controller Enable pin of the associated rail. This

will ensure that and SPS OC event will be detected and the

converter will shut down.

Thermal Monitoring and Protection

The TWARN pin indicates the temperature status of the voltage

regulator. The TWARN pin is an open-drain output and an

external pull-up resistor is required. This signal is valid only after

the controller is enabled.

The TWARN signal can be used to inform the system that the

temperature of the voltage regulator is too high and the load

should reduce its power consumption. TWARN only indicates a

thermal warning, not a fault.

The thermal monitoring function block diagram is shown in

Figure 24 on page 19. The ISL68147 has two over-temperature

thresholds, which allow both warning and fault indications. Each

temperature sensor threshold can be independently

programmed in PowerNavigator. Figure 25 on page 19 shows the

thermal warning to TWARN and Figure 26 on page 19 shows the

over-temperature fault to shut down. PGOOD and TWARN can be

configured to indicate these warning and fault thresholds

through PowerNavigator.

FIGURE 20. OCP_FAST

PLACEHOLDER

PGOOD

PWM

OCP_SLOW_THRESHOLD

OCP_FAST_THRESHOLD

OCP_FAST COUNTER

FILTER TIME CONSTANT

FIGURE 21. OCP_SLOW

PLACEHOLDER

PGOOD

PWM

OCP_FAST_THRESHOLD

OCP_SLOW_THRESHOLD

OCP_SLOW COUNTER

FILTER TIME

CONSTANT

FIGURE 22. POSITIVE PEAK PHASE CURRENT LIMITING

TWARN

PGOOD

PWM

POSITIVE_CURRENT_LIMITING_PER_PHASE

FIGURE 23. NEGATIVE PEAK PHASE CURRENT LIMITING

TWARN

PGOOD

PWM

NEGATIVE_CURRENT_LIMITING_PER_PHASE

ISL68147IRAZ Datasheet(PDF) 18 Page - Renesas Technology Corp

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