ISL97635IRZ datasheet(16/28 Pages) RENESAS

16 / 28 page

ISL97635

FN6434 Rev.3.00

Page 16 of 28

Sep 26, 2017

7CH0 LED Open Circuit

but has paralleled

Zener

Upper OTP not triggered

but VIIN0 > VSC

CH0 OFF

CH1 through CH7 Normal

Highest VF of CH1

through CH7

Upper OTP not triggered

but VIINx > VSC

CH0 remains ON and has highest VF,

thus VOUT increases.

VOUT increases then CH-X switches

OFF. This is an unwanted shut off

and can be prevented by setting

OVP and/or VSC at an appropriate

level.

VF of CH0

Channel-to-Channel

VF too high

Lower OTP triggered but

VIINx < VSC

Any channel at below 50% of the target current will fault out after 400µs.

Remaining channels driven with normal current.

Highest VF of CH0

through CH7

Channel-to-Channel

VF too high

Upper OTP triggered but

VIINx < VSC

All channels switched off until chip cooled and then comes back on with

current reduced to 76%. Further OTP triggers result in reduction to 53%,

then 30%. Thermal event reported in Fault/Status Register.

Highest VF of CH0

through CH7

Output LED stack

voltage too high

VOUT > VOVP

Driven with normal current. Any channel that is below 50% of the target

current will time-out after 6ms.

Highest VF of CH0

through CH7

VOUT/LX shorted to

GND

LX current and timing are

monitored.

OVP pin monitored for

excursions below 20% of

OVP threshold

Fault switch disabled and system shutdown until fault goes away, VOUT is

checked at start-up with a low current from LX to check for presence of

short before the fault switch is enabled.

TABLE 1. PROTECTIONS TABLE (Continued)

CASE

FAILURE MODE

DETECTION MODE

FAILED CHANNEL ACTION

GOOD CHANNELS ACTION

VOUT REGULATED

FIGURE 20. SMBUS INTERFACE

VIH

VIL

VIH

VIL

tLOW

tHD:STA

tHD:DAT

tHIGH

tSU:DAT

tSU:STA

tSU:STO

SMBDAT

SMBCLK

NOTES:

SMBus Description

S = Start condition

P = Stop condition

A = Acknowledge

A = Not acknowledge

R/W = Read enable at high; write enable at low

tBUF

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