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| AT9917 Datasheet, PDF (1/12 Pages) Supertex, Inc – Automotive LED Driver IC with High Current Accuracy | |||
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Supertex inc.
AT9917
Automotive LED Driver IC
with High Current Accuracy
Features
⺠Switch mode controller for boost, SEPIC & buck
converters
⺠Closed loop control of output current
⺠High PWM dimming ratio
⺠Internal 40V linear regulator
⺠Internal 3% voltage reference
⺠Constant frequency operation with programmable
slope compensation
⺠Linear and PWM dimming
⺠Programmable jitter to reduce EMI
⺠+/-1.0A MOSFET gate driver
⺠Output short circuit protection
⺠Output over voltage protection
⺠Programmable hiccup timer
⺠Temperature fold-back with external NTC resistor
⺠Soft start
⺠Meets AEC-Q100 requirements
Applications
⺠Automotive LED driver applications
General Description
The AT9917 is an advanced ï¬xed frequency PWM IC
designed to control single-switch, boost, SEPIC, and buck
LED drivers in a constant current mode. The controller uses a
peak current-mode control scheme (with programmable slope
compensation) and includes an internal transconductance
ampliï¬er to control the output current with high accuracy.
The IC includes a +/-1A gate driver that makes the AT9917
suitable for high power applications. An internal 40V linear
regulator powers the IC eliminating the need for a separate
power supply for the IC. The IC provides a FAULT output,
which can be used to disconnect the LEDs in case of a fault
condition (such as an alternator load dump in automobiles)
using an external disconnect FET. AT9917 also provides a
TTL compatible, low-frequency PWM dimming input that
can accept an external control signal with a duty ratio of 0-
100% and a frequency of up to several kilohertz. Temperature
foldback of the output current is possible, using an external
NTC resistor.
The AT9917-based LED driver is suited for automotive LED
driver applications. The AT9917 based LED lamp drivers can
achieve efï¬ciencies in excess of 90% when buck or boost
topologies are used.
Typical Boost Application Circuit
D2 (Optional)
D1
CIN
CIN1
L1
Q1
Co
CPVDD
CSC
RSC
RCS
PVDD AVDD GT
CS
PGND OVP
VIN
FLT
Q2
GND
R4
FDBK
EN
AT9917
PWMD
RT
COMP
CC
RS
IREF
RT
SS
JT
NTC DIV T1
T2 REF
CSS
CJTR
R1
RR1
R3 CREF
RR2
R2
Supertex inc. â 1235 Bordeaux Drive, Sunnyvale, CA 94089 â Tel: 408-222-8888 â www.supertex.com
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