isl97636 Intersil Corporation, isl97636 Datasheet - Page 13

• Manufacturer Part Number: isl97636
• Description: 8-channel Led Driver
• Manufacturer: Intersil Corporation

CASE
1
2
3
4
5
CH0 Short Circuit
CH0 Short Circuit
CH0 Short Circuit
CH0 Open Circuit
with infinite
resistance
CH0 LED Open
Circuit but has
paralleled Zener
FAILURE MODE
VIN
IMAX
DRIVER
ILIMIT
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
13
DETECTION
FAULT
MODE
LOGIC
GENERATOR
FIGURE 18. SIMPLIFIED FAULT PROTECTIONS
DETECT
FAULT
LOGIC
PWM
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%.
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
FAILED CHANNEL ACTION
TABLE 1. PROTECTIONS TABLE
DRIVER
SHORT
THRM
THRM
SHDN
SHDN
FET
O/P
OTP
OTP
PWM/OC0/SC0
ISL97636
VSET
LX
VSC
VSC
LX
OVP
T2
T1
SENSOR
TEMP
REF
CH1 through CH7 Normal
Same as CH0
CH1 through CH7 Normal
CH1 through CH7 Normal
CH1 through CH7 ON, Q1 through
Q7 burn power
GOOD CHANNELS ACTION
VOUT
Q0
PWM/OC7/SC7
IIN0
VSET
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
REGULATED BY
Q7
IIN7
VOUT
May 9, 2008
FN6570.0