ISL97671IRZ-T Intersil, ISL97671IRZ-T Datasheet - Page 15

• Manufacturer Part Number: ISL97671IRZ-T
• Description: IC LED DVR PWM CTRL 6CH 20QFN
• Manufacturer: Intersil

Specifications of ISL97671IRZ-T

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Automotive, Backlight
• Type - Secondary: RGB, White LED
• Frequency: 600kHz ~ 1.2MHz
• Voltage - Supply: 4.5 V ~ 26.5 V
• Mounting Type: Surface Mount
• Package / Case: 20-VFQFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 40mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -

channel making all other channel look as if they have
LED shorts. See Table 1 for details for responses to fault
conditions.
Overvoltage Protection (OVP)
The integrated OVP circuit monitors the output voltage
and keeps the voltage at a safe level. The OVP threshold
is set as:
These resistors should be large to minimize the power
loss. For example, a 1MkΩ R
OVP to 41.2V. Large OVP resistors also allow C
discharges slowly during the PWM Off time. Parallel
capacitors should also be placed across the OVP resistors
such that R
C
capacitors reduce the AC impedance of the OVP node,
which is important when using high value resistors.
Undervoltage Lock-out
If the input voltage falls below the UVLO level of 2.45V,
the device will stop switching and be reset. Operation will
restart only if the device is re-enabled through
SMBus/I
normal V
applications, the part will automatically restart once the
input voltage clears the UVLO threshold with the part
already enabled.
Input Overcurrent Protection
During normal switching operation, the current through
the internal boost power FET is monitored. If the current
exceeds the current limit, the internal switch will be
turned off. This monitoring happens on a cycle by cycle
basis in a self protecting way.
OVP
UPPER
=
1.21V
value of at least 30pF is recommended. These
2
IN
C interface once the input voltage is back in the
UPPER
and operating range. In non-SMBus/I
×
(
R
UPPER
/R
LOWER
+
R
= C
LOWER
15
UPPER
LOWER
) R
⁄
and 30kΩ R
/C
LOWER
UPPER
. Using a
LOWER
OUT
2
(EQ. 15)
C
ISL97671
sets
Additionally, the ISL97671 monitors the voltage at the LX
and OVP pins. At startup, a fixed current is injected out of
the LX pins and into the output capacitor. The device will
not start up unless the voltage at LX exceeds 1.2V. The
OVP pin is also monitored such that if it rises above and
subsequently falls below 20% of the target OVP level, the
input protection FET will also be switched off.
Over-Temperature Protection (OTP)
The ISL97671 includes two over-temperature thresholds.
The lower threshold is set to +130°C. When this
threshold is reached, any channel which is outputting
current at a level significantly below the regulation target
will be treated as “open circuit” and disabled after a time-
out period. This time-out period is also reduced to 800µs
when it is above the lower threshold. The intention of the
lower threshold is to allow bad channels to be isolated
and disabled before they cause enough power dissipation
(as a result of other channels having large voltages
across them) to hit the upper temperature threshold.
The upper threshold is set to +150°C. Each time this is
reached, the boost will stop switching and the output
current sources will be switched off. Once the device has
cooled to approximately +100°C, the device will restart
with the DC LED current level reduced to 75% of the
initial setting. If the dissipation problem persists,
subsequent hitting of the limit will cause identical
behavior, with the current reduced in steps to 50% and
finally 25%. Hitting of the upper threshold will also set
the thermal fault bit of the Fault/Status register 0x02.
Unless disabled via the EN pin, the device stays in an
active state throughout, allows the external processor to
interrogate the fault condition.
For the extensive fault protection conditions, please refer
to Figure 25 and Table 1 for details.
June 24, 2010
FN7631.0