LED DRIVER. IS32LT3953 Datasheet


IS32LT3953 DRIVER. Datasheet pdf. Equivalent


IS32LT3953


CONSTANT-CURRENT 3-AMPERE PWM DIMMABLE BUCK REGULATOR LED DRIVER
IS32LT3953
CONSTANT-CURRENT 3-AMPERE PWM DIMMABLE BUCK REGULATOR LED DRIVER

Advanced Information December 2013

GENERAL DESCRIPTION
The IS32LT3953 is a DC-to-DC switching converter with an integrated N-channel MOSFET operating in a buck configuration. The device is connected to a voltage higher than the LED voltage; between 6V and 48V and provides a constant current of up to 3.0A for driving a single LED or multiple series connected LEDs.
The LED output current is set by an external current sense resistor, allowing the output voltage to be automatically adjusted for a variety of LED configurations.
The IS32LT3953 operates in a fixed frequency mode during switching. The on-time (switching frequency) is programmed using an external resistor connected between the VIN and TON pins.
LED dimming is accomplished by applying a logic input PWM (pulse-width-modulation) signal to the enable (EN) pin. The resulting LED brightness is proportional to the duty cycle of the PWM signal. True average current is output using cycle-by-cycle, controlled on-time method.
The IS32LT3953 is offered in an SOP-8-EP package with an exposed pad for enhanced thermal dissipation. The operating temperature range is from -40°C to +125°C.

FEATURES
 Supply voltage 6V ~ 48V  True average output current control  3.0A maximum output over operating temperature
range  Cycle-by-cycle current limit  Integrated M...



IS32LT3953
IS32LT3953
CONSTANT-CURRENT 3-AMPERE PWM DIMMABLE BUCK
REGULATOR LED DRIVER WITH FAULT PROTECTION
December 2018
GENERAL DESCRIPTION
The IS32LT3953 is a DC-to-DC switching converter
that integrates an N-channel MOSFET to operate in a
buck configuration. The device can operate from a
wide input voltage between 4.5V and 38V and
provides a constant current of up to 3A for driving a
single LED or multiple series connected LEDs.
The external resistor, RISET, is used to set a constant
LED output current, while allowing the output voltage
to be automatically adjusted for a variety of LED
configurations.
The IS32LT3953 operates in a fixed frequency mode
during switching. There is an external resistor
connected between the VCC and TON pins used to
configure the on-time (switching frequency). The
switching frequency is dithered for spread spectrum
operation which will spread the electromagnetic
energy into a wider frequency band. This function is
helpful for optimizing EMI performance.
A logic input PWM signal applied to the enable (EN)
pin will adjust the average LED current. The LED
brightness is proportional to the duty cycle of the
PWM signal.
True average output current operation is achieved
with fast transient response by using cycle-by-cycle,
controlled on-time method.
The IS32LT3953 is available in an SOP-8-EP
package with an exposed pad for enhanced thermal
dissipation. It operates from 4.5V to 38V over the
temperature range of -40°C to +125°C.
FEATURES
Wide input voltage supply from 4.5V to 38V
- Withstand 40V load dump
True average output current control
3A maximum output over operating temperature
range
Cycle-by-cycle current limit
Integrated high-side MOSFET switch
Dimming via direct logic input or power supply
voltage
Internal control loop compensation
Under-voltage lockout (UVLO) and thermal
shutdown protection
2μA low power shutdown
Spread spectrum to optimize EMI
Robust fault protection:
- Pin-to-GND short
- Component open/short faults
- Adjacent pin-to-pin short
- LED open/short
- Thermal shutdown
AEC-Q100 Qualified
APPLICATIONS
Automotive and avionic lighting
Daytime running lights
Turn/stop lights
Front and rear fog lights
Matrix headlight
Motorcycle headlight
TYPICAL APPLICATION CIRCUIT
Figure 1 Typical Application Circuit
Integrated Silicon Solution, Inc. – www.issi.com
Rev. C, 12/25/2018
1

IS32LT3953
IS32LT3953
PIN CONFIGURATION
Package
Pin Configuration (Top View)
SOP-8-EP
PIN DESCRIPTION
No. Pin
1 VCC
2 TON
3 EN/PWM
4 FB
5, 6 GND
7 BOOT
8 LX
Thermal Pad
Description
Power supply input. Connect a bypass capacitor CIN to ground.
The path from CIN to GND and VCC pins should be as short as
possible.
On-time setting. Connect a resister from this pin to VCC pin to
set the regulator controlled on-time.
Logic input for enable and PWM dimming. Pull up above 1.4V to
enable and below 0.4V to disable. Input a 100Hz~20kHz PWM
signal to dim the LED brightness.
Drive output current sense feedback. Set the output current by
connecting a resister from this pin to the ground.
Ground. Both pins must be grounded.
Internal MOSFET gate driver bootstrap. Connect a 0.1µF X7R
ceramic capacitor from this pin to LX pin.
Internal high-side MOSFET switch output. Connect this pin to
the inductor and Schottky diode.
Connect to GND.
Integrated Silicon Solution, Inc. – www.issi.com
Rev. C, 12/25/2018
2




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