Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 7

Copyright

© 2000

Rev. 1.1b, 2005-03-03

LX1992

High Efficiency LED Driver

TM

®

Figure 5: LXE1992 Engineering Evaluation Board

Table 1: Input and Ouput Pin Assignments

Pin Name

Allowable Range

Description

VBAT

0 to 6V

Main power supply for output. (Set external current limit to 0.5A)

VCC

1.6V to 6V

LX1992 power. May be strapped to VBAT or use a separate supply if VCC jumper is in

the SEP position. Do not power output from VCC pin on board..

VPOT

1.6V to 6V

Potentiometer power. May be strapped to VBAT or use a separate supply if VPOT

jumper is in the SEP position. Do not power output from VPOT pin on board.

VADJ IN

0 to 350mV

Apply a DC voltage or a PWM voltage to this pin to adjust the LED current. PWM

inputs should be greater than 120Hz and DC portion less than 350mV.

/SHDN

0 to VCC

Pulled up to VCC on board (10KΩ), Ground to inhibit the LX1992.

VOUT

0 to 18V

Power supply output voltage that is applied to LED string.

VFDBK

0 to 400mv

Sense resistor voltage. Divide this voltage by 15 to determine LED current.

Table 2: Jumper Pin Position Assignments

Jumper Position

Functional Description

VCC/ BAT

Use this position when powering VBAT and VCC from the same supply. Do not connect power to the VCC

input when using this jumper position.

VCC/ SEP

Use this position when using a separate VCC supply (different from VBAT).

VPOT/ VBAT

Use this position when powering the potentiometer reference circuit from the VBAT supply. Do not connect

power to the VCC input when using this jumper position.

VPOT/ SEP

Use this position when using a separate power supply (different from VBAT) to power the potentiometer

reference circuit. This will lower the VBAT current and provide a more accurate efficiency reading for the

LX1992 circuit.

ADJ/ POT

Use this position when using the potentiometer to adjust LED current.

ADJ/ EXT

Use this position when adjusting the LED current with an external PWM that has a repetition rate >120Hz. Or

when using a DC adjustment voltage.

Note: Always put jumpers in one of the two possible positions