isl97635 Intersil Corporation, isl97635 Datasheet - Page 16

• Manufacturer Part Number: isl97635
• Description: Smbus 8-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
TABLE 1. PROTECTIONS TABLE
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
V
time-out after 6ms (800µs if above
lower OTP limit) and switch off.
V
CH0 remains ON and has highest
VF, thus V
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 V
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,
V
presence of short before the fault switch is enabled.
OUT
OUT
OUT
FAILED CHANNEL ACTION
will ramp to OVP. CH0 will
will drop to normal level.
is checked at start-up with a low current from LX to check for
ISL97635
OUT
OUT
increases
increases.
CH1 through CH7 Normal
Same as CH0
CH1 through CH7 Normal
CH1 through CH7 Normal
CH1 through CH7 ON, Q1
through Q7 burn power
Same as CH0
CH1 through CH7 Normal
V
switches OFF. This is an
unwanted shut off and can be
prevented by setting OVP and/or
VSC at an appropriate level.
OUT
GOOD CHANNELS ACTION
increases then CH-X
Highest VF of
CH1 through CH7
Highest VF of
CH1 through CH7
Highest VF of
CH1 through CH7
Highest VF of
CH1 through CH7
VF of CH0
VF of CH0
Highest VF of
CH1 through CH7
VF of CH0
Highest VF of
CH0 through CH7
Highest VF of
CH0 through CH7
Highest VF of
CH0 through CH7
REGULATED BY
December 22, 2008
VOUT
FN6434.2