ST L99LD01 User Manual
Features
L99LD01
High efficiency constant current LED driver
Data brief
Max V
BATT
Operation supply battery voltage
V
BATT
Oscillator frequency range 100 - 500 KHz
■ Constant current operation
■ Current LED settable by external sensing
40 V
5.6 - 24 V
resistor and adjustable via SPI
■ Converter switching frequency adjustable by
external resistor (R
■ EMC reduction by internal spread spectrum
SF
)
dither oscillator
■ Low frequency PWM dimming operation
■ Maximum input current limiter
■ Maximum switching duty cycle limiter
■ Slope compensation adjustable by external
resistor (R9)
■ Battery over voltage shut down protection (ext.
R3,R4 resistors required)
■ Led chain OV detection (ext. R5, R6)
■ Multiplexed output for monitoring and control of
LED temperature (external NTC resistor
required), voltage of LED chain, and low
frequency PWM
■ SPI communication serial interface transceiver
(SDI, SDO, SCK, CSN)
■ Parameter programming and settings of
internal memory registers by the dedicated SPI
interface:
– LED current reference adjusting (± 66.7 %)
– Maximum input current limiter reference
adjusting (± 55.5 %)
– Random dither frequency sweeping,
modulation frequency and deviation
percentage
LQFP32 7x7mm
■ Regulated output for micro supply
5V±2%-20mA
■ Power on reset pin output
■ ESD protection
Applications
Automotive day time running light, LED
headlamps.
Description
L99LD01 is a complete constant current DC-DC
converter LED driver, manufactured in a BCD5S
70 V technology and assembled in a LQFP32
package.
The device is designed to be used in boost, buckboost and fly back converter topologies. An
internal random dither oscillator works in low
frequency modulation, allowing spreading the RF
spectrum of the switching frequency, so reducing
EMC emissions. The slope compensation
ensures good converter loop stability whatever is
the duty cycle needed by the application.
The converter is able to work either in full power
mode or in low frequency dimming mode.
The device includes an internal low drop voltage
regulator, that can be used to supply a
microcontroller, and a reset pin, that is useful for
resetting the microcontroller at the start up and
every time that the regulated output voltage falls
down below an established voltage threshold.
TM
February 2011 Doc ID 18451 Rev 1 1/3
For further information contact your local STMicroelectronics sales office.
www.st.com
1
Revision history L99LD01
1 Revision history
Table 1. Document revision history
Date Revision Changes
04-Feb-2011 1 Initial release.
2/3 Doc ID 18451 Rev 1
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