LT8355-1

1

Rev. A

For more information www.analog.com

TYPICAL APPLICATION

FEATURES

DESCRIPTION

60VIN/120VOUT Dual LED

Controller with Exponential PWM

and Scalable Dimming

The LT®8355-1 a dual-channel DC/DC controller designed

to drive two strings of high current LEDs. The fixed fre-

quency, current mode architecture results in stable oper-

ation over a wide range of supply and output voltages.

Voltage feedback pins serve as the inputs for several LED

protection features and makes it possible for the convert-

ers to operate as a constant-voltage sources.

The LT8355-1 senses output current at the high or low

side of the load. The product of CTRL2 and IADJ2 inputs

provides analog programming of the output current for

channel 2. Channel 1 output current is programmed

through CTRL1 input. The PWM input and PWMTG high

side PMOS driver provides precision time-based LED

dimming capability. When driven by an external digital

signal, the PWM input provides LED dimming ratios of up

to 20,000:1 at 100Hz. When driven by a constant voltage,

the PWM input selects from one of 128 internally gen-

erated, precision, exponentially spaced dimming ratios

ranging from 0.78% up to 100%.

Dual 32W Boost LED Driver

APPLICATIONS

n

Two independent High Voltage LED Driver

Controllers Channels

n

128:1 Internal Exponential PWM Dimming

n

Two-Pin Multiplying Analog Dimming (CH2)

n

Spread Spectrum Frequency Modulation

n

20,000:1 External PWM Dimming at 100Hz

n

Rail-to-Rail LED Current Sensing: 0V to 120V

n

±2% LED Current Regulation

n

±2% Output Voltage Regulation

n

LED Short/Open Protection and Indication

n

Wide Input Voltage Range (5V to 60V)

n

PMOS Switch Driver for PWM and Output Disconnect

n

Independent Channel Dimming

n

Constant-Voltage and Constant-Current Regulation

n

Adjustable Switching Frequency 100kHz to 2MHz

n

Independent OPEN/SHORT LED FAULT per channel

n

Programmable VIN UVLO with Hysteresis

n

Side Solderable 28-Lead 4mm × 5mm QFN Package

n

AEC-Q100 Qualified for Automotive Applications

n

High Voltage LED Applications

n

Automotive Head Lamps/Running Lamps

n

Accurate Current Limited Voltage Regulator

All registered trademarks and trademarks are the property of their respective owners. Protected

by U.S. patents, including 7199560, 7321203, 7746300, 8116045.

500m

51.1k

499k

15µH

4.7µF

147k

0.47nF

40.2k

2.2µF

12.5m

500m

15µH

10µF

10k

12.5m

10µF

576k

100k

VIN

(6V TO 36V)

GATE1

SENSEN1

ILIM = 8A

PWM1

CHANNEL 1

DIMMING

VREF

RT

0.5A

INTVCC

FAULT1-2

f = 400kHz

LT8355-1

SENSEP1

ISP1

ISN1

PWMTG1

VIN

EN/UVLO

VC1-2

FB1-2

ISN1-2

ISP1-2

CTRL1-2

IADJ2

PWM2

CHANNEL 2

DIMMING

GATE2

SENSEN2

ILIM = 8A

0.5A

SENSEP2

ISP2

ISN2

PWMTG2

32W

LED

ARRAY

GND

32W

LED

ARRAY

8355-1 TA01a

BOTH CHANNELS

CH1 ONLY

CH2 ONLY

VIN (V)

6

12

18

24

30

36

70

73

76

79

82

85

88

91

94

83551 TA01b