Specifications
74
A 10-bit AD converter from Linear Technology (LTC1392) is used on-board. This
component also contains a temperature sensor. The 5 V supply voltage is measured
internally by a multiplexer of the LTC1392. Before the LTC1392. chip, an eight
channel multiplexer is put in line. This multiplexer measures several voltages on the
board. Please refer to the following table for the analog multiplexer input signals:
Channel 1 Programming voltage (12 Volt)
Channel 2 12 Volt
Channel 3 5 Volt (switched) voltage for LC-display
Channel 4 12 Volt (switched) voltage for LC-display
Channel 5 Keyboard voltage (5 Volt)
Channel 6 Positive contrast voltage (max. 30 Volt)
Channel 7 Negative contrast voltage (max. 30 Volt)
Channel 8 Battery voltage (3 volt)
Before programming the LTC1390 or LTC1392. converters, please refer to the com-
ponent data sheets.
DA Converter for LCD Contrast Control
Bit Name Function
1 CS Chip select for multiplexer and AD converter
0 DATA Data for multiplexer and from AD converter
Index: 6 Data Port Description
ADCTRL RES RES RES RES RES RES CS DATA
PWR x x x x x x x x
x x x x x x w r/w
D7 D6 D5 D4 D3 D2 D1 D0
AD Converter and Temperature Sensor
Bit Name Funtion
1 LOAD Load impulse for DA converter
0 DATA Data for DA converter
The DA converter used on-board is a 12-bit converter from Linear Technology
(LTC1451). To avoid damaging the display, always check that the desired value is
supported by the connected display.
Index: 5 Data Port Description
DACTRL RES RES RES RES RES RES LOAD DATA
PWR x x x x x x x 0
x x x x x x w r/w
D7 D6 D5 D4 D3 D2 D1 D0