LX1970
E
VALUATION
B
OARD
U
SER
G
UIDE
Copyright © 2002
Microsemi
Page
4
Rev. 1.1 9/23/03
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Input
Allowable Range
Description
VDD
2 to 5.5V
LX1970 power supply if J1 is set to LX1970 only, or LX1970 power
supply and LX1990 and external LED’s power supply if J1 is
connected to LED DRIVER (LED’s will only light if J4 is also in
DRIVER position.
GND
0V
Common ground reference
SRC
Diode
Pull-down
5V to GND, fixed
DC voltage or
PWM/Logic signal
This diode connection is generally used to shunt SRC output current
when disengaging the sensor in a full manual mode
SRC
Adjust
Pull-up
5V to GND, fixed
DC voltage or
PWM/Logic signal
First pull-up connection is generally used to set a minimum output
voltage or adjust output transfer slope for SRC pin
SRC
Fixed
Pull-up
5V to GND, fixed
DC voltage or
PWM/Logic signal
Second pull-up connection is generally used to set a minimum
output voltage or adjust output transfer slope for SRC pin
SNK Pull-
up
5V to GND, fixed
DC voltage or
PWM/Logic signal
This pull-up connection is generally used to set a maximum output
voltage or adjust output transfer slope for SNK pin
Table 1
– Evaluation Board Terminals
Jumper
Function
J1
Jumper to LED Driver connects LX1990 driver IC & LX1970 to VDD, Jumper to LX1970
only connects VDD to the LX1970 sensor only.
J2
Jumper to SRC open disconnects external divider circuitry from LX1970 SCR pin. Jumper
to DIVIDER connects external divider circuitry to SRC pin.
J3
Shorts or leaves connect the series diode D2 from SRC pull-down path
J4
Jumper to DRIVER connects the SNK output to the ISET input of the LX1990 through a
4.12K resistor. Jumper to SNK Pull-up connects the SNK pin to the SNK Pull-up external
board connection
Table 2
– Jumper Explanation
Test Point
Description
GND
Common Ground Reference
VDD
VDD Input to LX1970 (2 to 5.5V)
SNK
LX1970 SNK output
SRC LX1970
SRC
output
SRC Diode
Pull-down
Cathode of diode connected to SRC pin
SRC Adjust
Pull-up
100K rheostat and series 10K resistor to SRC
SRC Fixed
Pull-up
50K series resistor to SRC
SNK Pull-up
100K rheostat and parallel 1µF capacitor to SNK
Table 3
– Terminal/Test Point Descriptions
