LX1992
High Efficiency LED Driver
L I N F I N I T Y D I V I S I O N
PRODUCTION
APPLICATION INFORMATION (CONTINUED)
Figure 5: LXE1992 Engineering Evaluation Board
Table 1: Input and Ouput Pin Assignments
Pin Name
Allowable Range
Description
VBAT
VCC
0 to 6V
Main power supply for output. (Set external current limit to 0.5A)
LX1992 power. May be strapped to VBAT or use a separate supply if VCC jumper is in
1.6V to 6V
the SEP position. Do not power output from VCC pin on board..
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.
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.
VPOT
1.6V to 6V
0 to 350mV
VADJ IN
/SHDN
VOUT
0 to VCC
0 to 18V
Pulled up to VCC on board (10KΩ), Ground to inhibit the LX1992.
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
Functional Description
Jumper Position
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).
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/ VBAT
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.
VPOT/ SEP
ADJ/ POT
ADJ/ EXT
Use this position when using the potentiometer to adjust LED current.
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
Copyright 2000
Rev. 1.1, 2002-11-21
Microsemi
Page 7
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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