GE Industrial Solutions 40A Digital MegaDLynx - Manual (Page 20)

GE
Data Sheet
40A Digital MegaDLynx TM : Non-Isolated DC-DC Power Modules
4.5Vdc –14.4Vdc input; 0.45Vdc to 2.0Vdc output; 40A Output Current
April 24, 2013 ©2012 General Electric Company. All rights reserved. Page 20
OFFSET CAL VOUT
GAIN CAL VOUT Initial V
Final V
OUT
OUT
_ _
)] _ _ 1 ( ) ( [
) (

 

Measuring Input Voltage Using the PMBus
The module can provide input voltage information using the
READ_VIN command. The command returns two bytes of
data in the linear format. The upper five bits [7:3] of the high
data form the two’s complement representation of the
exponent which is fixed at –5 (decimal). The remaining 11 bits
are used for two’s complement representation of the
mantissa, with the 11
th bit fixed at zero since only positive
numbers are valid.
During module manufacture, offset and gain correction
values are written into the non-volatile memory of the
module. The command VIN_CAL_OFFSET can be used to read
and/or write the offset - two bytes consisting of a five-bit
exponent (fixed at -5) and a11-bit mantissa in two’s
complement format. The allowed range for this offset
correction is -2 to 1.968V, and the resolution is 32mV. The
command VIN_CAL_GAIN can be used to read and/or write
the gain correction - two bytes consisting of a five-bit
exponent (fixed at -8) and a 11-bit mantissa. The range of this
correction factor is -0.125V to +0.121V, with a resolution of
0.004V. The corrected output voltage reading is then given
by:
OFFSET CAL VIN
GAIN CAL VIN Initial V
Final V
IN
IN
_ _
)] _ _ 1 ( ) ( [
) (

 

Reading the Status of the Module using the PMBus
The module supports a number of PMBus status information
commands. However, not all features are supported in these
commands. A 1 in the bit position indicates the fault that is
flagged.
STATUS_BYTE : Returns one byte of information with a
summary of the most critical device faults.
Bit Position Flag
Default
Value
7 X 0
6 OFF 0
5 VOUT Overvoltage 0
4 IOUT Overcurrent 0
3 VIN Undervoltage 0
2 Temperature 0
1 CML (Comm. Memory Fault) 0
0 None of the above 0
STATUS_WORD: Returns two bytes of information with a
summary of the module’s fault/warning conditions.
Low Byte
Bit Position Flag
Default
Value
7 X 0
6 OFF 0
5 VOUT Overvoltage 0
4 IOUT Overcurrent 0
3 VIN Undervoltage 0
2 Temperature 0
1 CML (Comm. Memory Fault) 0
0 None of the above 0
High Byte
Bit Position Flag
Default
Value
7 VOUT fault or warning 0
6 IOUT fault or warning 0
5 X 0
4 X 0
3 POWER_GOOD# (is negated) 0
2 X 0
1 X 0
0 X 0
STATUS_VOUT : Returns one byte of information relating to
the status of the module’s output voltage related faults.
Bit Position Flag
Default
Value
7 VOUT OV Fault 0
6 X 0
5 X 0
4 VOUT UV Fault 0
3 X 0
2 X 0
1 X 0
0 X 0
STATUS_IOUT : Returns one byte of information relating to the
status of the module’s output voltage related faults.
Bit Position Flag
Default
Value
7 IOUT OC Fault 0
6 X 0
5 IOUT OC Warning 0
4 X 0
3 X 0
2 X 0
1 X 0
0 X 0