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TPCMQ48 SERIES
INSTALLATION & OPERATING MANUAL
Manual No. tpcmq48-4
tpcmq48-man-rev4-0116.indd
BIT
7
6
5
4
3
2
1
0
HEX ADDRESS
RANGE
0x90 – 0x9E
VALUE
1
0
0
1
GA2 GA1 GA0 R/W
The PCF8591 devices initially require a control byte (04 Hex) to be written to the
configuration register. This control byte sets the device so that on each successive read the
data from the next A/D is read.
Note that on each read a conversion is started for a particular channel and the result will be
read from the previous channel, thus the first result from a sequence of reads should always
be discarded.
A/D Converter scaling
To obtain a correct voltage or current measurement it is necessary to employ a scaling factor
in the controlling software. Note that all voltage measurements are made inside the PSU
module, before the ‘ORing’ devices, and are typically 0.5V higher than the actual module
output voltage. The calculation given in the following table should be employed.
Value = (byte read x scaling factor)
Output
Voltage Scaling Tolerance
12V
0.0625
±2%
V Measure (U1 A/D Chan. 1)
24V
0.1225
±2%
48V
0.24
±2%
12V
0.27
±10%*
I Measure (U1 A/D Chan. 2)
24V
0.145
±10%*
48V
0.084
±10%*
*of full scale
20.3.4 EEPROM Functions
The EEPROM is a 2048 bit (256 byte) device which is pre-programmed at the factory with
the data given in the following table.
Note that other data may be specified to special order. Please consult sales.
