ISL97678IRZ-TK 데이터 시트보기 (PDF) - Intersil

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ISL97678IRZ-TK

8-Channel 45V 50mA LED Driver

Intersil 

ISL97678

VIN

FAULT

DRIVER

IMAX ILIMIT

LOGIC

O/P

SHORT

FET

DRIVER

LX

OVP

VSC

VOUT

CH1

VSET/2

REG

THRM

SHDN

REF

OTP

VSET +

-

PWM1/OC1/SC1

T2

TEMP

SENSOR

T1

Q1 VSET +

-

PWM8/OC8/SC8

CONTROL

LOGIC

DC CURRENT

FIGURE 25. SIMPLIFIED FAULT PROTECTIONS

CH8

Q8

TABLE 1. PROTECTIONS TABLE

CASE FAILURE MODE

DETECTION MODE

FAILED CHANNEL ACTION GOOD CHANNELS ACTION

VOUT

REGULATED

BY

1 CH1 Short Circuit Upper

CH1 ON and burns power

Over-Temperature

Protection limit (OTP)

not triggered and

VIIN0 < VSC

2 CH1 Short Circuit Upper OTP triggered CH1 goes off

but VIN1 < VSC

CH2 through CH8 Normal

Highest VF of

CH2 through

CH8

Same as CH1

Highest VF of

CH2 through

CH8

3 CH1 Short Circuit Upper OTP not

CH1 disabled after 6 PWM

triggered but VIIN1 > cycles time-out.

VSC

If 3 channels are already

Highest VF of

shut down, all channels will CH2 through

be shut down. Otherwise

CH8

CH2-8 will remain as normal

4 CH1 Open Circuit Upper OTP not

VOUT will ramp to OVP. CH1 will CH2 through CH8 Normal

with infinite

triggered and VIIN1 time-out after 6 PWM cycles

resistance

< VSC

and switch off. VOUT will drop

to normal level.

Highest VF of

CH2 through

CH8

5 CH1 LED Open Upper OTP not

CH1 remains ON and has

Circuit but has

triggered and VIIN1 < highest VF, thus VOUT

paralleled Zener VSC

increases

CH2 through CH8 ON, Q2

through Q8 burn power

VF of CH1

6 CH1 LED Open Upper OTP triggered CH1 goes off

Circuit but has

but VIIN1 < VSC

paralleled Zener

Same as CH1

VF of CH1

14

FN6998.1

November 5, 2009

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