isl97635a Intersil Corporation, isl97635a Datasheet - Page 16

• Manufacturer Part Number: isl97635a
• Description: Smbus 6-channel Led Driver
• Manufacturer: Intersil Corporation

CASE
10
11
1
2
3
4
5
6
7
8
9
CH0 Short Circuit
CH0 Short Circuit
CH0 Short Circuit
CH0 Open Circuit
with infinite
resistance
CH0 LED Open
Circuit but has
paralleled Zener
CH0 LED Open
Circuit but has
paralleled Zener
CH0 LED Open
Circuit but has
paralleled Zener
Channel-to-Channel
ΔVF too high
Channel-to-Channel
ΔVF too high
Output LED stack
voltage too high
VOUT/LX shorted to
GND
FAILURE MODE
Upper
Over-Temperature
Protection limit
(OTP) not
triggered and
VIIN0 < VSC
Upper OTP
triggered but VIN0
< VSC
Upper OTP not
triggered but
VIIN0 > VSC
Upper OTP not
triggered and
VIIN0 < VSC
Upper OTP not
triggered and
VIIN0 < VSC
Upper OTP
triggered but
VIIN0 < VSC
Upper OTP not
triggered but
VIIN0 > VSC
Upper OTP not
triggered but VIINx
> VSC
Lower OTP
triggered but VIINx
< VSC
Upper OTP
triggered but VIINx
< VSC
VOUT > VOVP
LX current and
timing are
monitored.
OVP pin
monitored for
excursions below
20% of OVP
threshold
16
DETECTION
MODE
CH0 ON and burns power
CH0 goes 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.
CH0 doubled after 6ms time-out.
Time-out reduced to 420µs if above
lower OTP limit
VOUT will ramp to OVP. CH0 will
time-out after 6ms (800µs if above
lower OTP limit) and switch off.
VOUT will drop to normal level.
CH0 remains ON and has highest
VF, thus VOUT increases
CH0 goes 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.
CH0 OFF
CH0 remains ON and has highest
VF, thus VOUT increases.
Any channel at below 50% of the target current will fault out after 400µs.
Remaining channels driven with normal current.
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.
Driven with normal current. Any channel that is below 50% of the target
current will time-out after 6ms.
Fault switch disabled and system shutdown until fault goes away, VOUT
is checked at startup with a low current from LX to check for presence of
short before the fault switch is enabled.
FAILED CHANNEL ACTION
TABLE 1. PROTECTIONS TABLE
ISL97635A
CH1 through CH5 Normal
Same as CH0
CH1 through CH5 Normal
CH1 through CH5 Normal
CH1 through CH5 ON, Q1 through
Q5 burn power
Same as CH0
CH1 through CH5 Normal
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.
GOOD CHANNELS ACTION
Highest VF of CH1
through CH5
Highest VF of CH1
through CH5
Highest VF of CH1
through CH5
Highest VF of CH1
through CH5
VF of CH0
VF of CH0
Highest VF of CH1
through CH5
VF of CH0
Highest VF of CH0
through CH5
Highest VF of CH0
through CH5
Highest VF of CH0
through CH5
REGULATED BY
December 22, 2008
VOUT
FN6564.2