GE Industrial Solutions 3A Digital PicoDLynx - Manual (Page 23)

GE
Data Sheet
3A Digital PicoDLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.45Vdc to 5.5Vdc output; 3A Output Current
April 29, 2013 ©2013 General Electric Company. All rights reserved. Page 23
T
IND
, it may be approximated by an estimate of the module
temperature.
Measuring Output Voltage Using the PMBus
The module can provide output voltage information using the
READ_VOUT command. The command returns two bytes of
data all representing the mantissa while the exponent is fixed
at -10 (decimal).
During manufacture of the module, offset and gain
correction values are written into the non-volatile memory of
the module. The command VOUT_CAL_OFFSET can be used
to read and/or write the offset (two bytes consisting of a 16-
bit mantissa in two’s complement format) while the exponent
is always fixed at -10 (decimal). The allowed range for this
offset correction is -125 to 124mV. The command
VOUT_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 VOUT
GAIN CAL VOUT Initial V
Final V
OUT
OUT
_ _
)] _ _ 1 ( ) ( [
) (
+
+ ×
=
Measuring Input Voltage Using the PMBus
The module can provide output 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 status information
commands implemented in PMBus. 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