GE Industrial Solutions 12A Digital PicoDLynx - Manual (Page 21)

GE
Data Sheet
12A Digital PicoDLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.45Vdc to 5.5Vdc output; 12A Output Current
November 19, 2013
©2013 General Electric Corporation.
All rights reserved.
Page 21
“Linear” mode with the exponent fixed at –10 (decimal). The
value of the offset voltage is given by
10
) (
2 _ − × = TRIM VOUT V
offset OUT
This offset voltage is added to the voltage set through the
divider ratio and nominal V
REF
to produce the trimmed output
voltage. The valid range in two’s complement for this
command is –4000h to 3999h. The high order two bits of
the high byte must both be either 0 or 1. If a value outside of
the +/-25% adjustment range is given with this command,
the module will set it’s output voltage to the nominal value
(as if VOUT_TRIM had been set to 0), assert SMBALRT#, set
the CML bit in STATUS_BYTE and the invalid data bit in
STATUS_CML.
Output Voltage Margining Using the PMBus
The module can also have its output voltage margined via
PMBus commands. The command VOUT_MARGIN_HIGH sets
the margin high voltage, while the command
VOUT_MARGIN_LOW sets the margin low voltage. Both the
VOUT_MARGIN_HIGH and VOUT_MARGIN_LOW commands
use the “Linear” mode with the exponent fixed at –10
(decimal). Two bytes are used for the mantissa with the upper
bit [7] of the high byte fixed at 0. The actual margined output
voltage is a combination of the VOUT_MARGIN_HIGH or
VOUT_MARGIN_LOW and the VOUT_TRIM values as shown
below.
10
) (
2 ) _ _ _ ( − × +
=
TRIM VOUT HIGH MARGIN VOUT
V
MH OUT
10
) (
2 ) _ _ _ ( − × +
=
TRIM VOUT LOW MARGIN VOUT
V
ML OUT
Note that the sum of the margin and trim voltages cannot be
outside the ±25% window around the nominal output
voltage. The data associated with VOUT_MARGIN_HIGH and
VOUT_MARGIN_LOW can be stored to non-volatile memory
using the STORE_DEFAULT_ALL command.
The module is commanded to go to the margined high or low
voltages using the OPERATION command. Bits [5:2] are used
to enable margining as follows:
00XX : Margin Off
0101 : Margin Low (Ignore Fault)
0110 : Margin Low (Act on Fault)
1001 : Margin High (Ignore Fault)
1010 : Margin High (Act on Fault)
PMBus Adjustable Overcurrent Warning
The module can provide an overcurrent warning via the
PMBus. The threshold for the overcurrent warning can be set
using the parameter IOUT_OC_WARN_LIMIT. This command
uses the “Linear” data format with a two byte data word
where the upper five bits [7:3] of the high byte represent the
exponent and the remaining three bits of the high byte [2:0]
and the eight bits in the low byte represent the mantissa.
The exponent is fixed at –1 (decimal). The upper five bits of
the mantissa are fixed at 0 while the lower six bits are
programmable. . For production codes after April 2013, the
value for IOUT_OC_WARN_LIMIT will be fixed at 14.5A. For
earlier production codes the actual value for
IOUT_OC_WARN_LIMIT will vary from module to module due
to calibration during production testing. The resolution of this
warning limit is 500mA. The value of the
IOUT_OC_WARN_LIMIT can be stored to non-volatile memory
using the STORE_DEFAULT_ALL command.
Temperature Status via PMBus
The module can provide information related to temperature
of the module through the STATUS_TEMPERATURE
command. The command returns information about
whether the pre-set over temperature fault threshold and/or
the warning threshold have been exceeded.
PMBus Adjustable Output Over and Under Voltage
Protection
The module has output over and under voltage protection
capability. The PMBus command VOUT_OV_FAULT_LIMIT is
used to set the output over voltage threshold from four
possible values: 108%, 110%, 112% or 115% of the
commanded output voltage. The command
VOUT_UV_FAULT_LIMIT sets the threshold that
causes an
output under voltage fault and can also be selected from
four possible values: 92%, 90%, 88% or 85%. The default
values are 112% and 88% of commanded output voltage.
Both commands use two data bytes formatted as two’s
complement binary integers. The “Linear” mode is used with
the exponent fixed to –10 (decimal) and the effective over or
under voltage trip points given by:
10
) _ (
10
) _ (
2 ) _ _ _ (
2 ) _ _ _ (
−
−
Ч =
Ч =
LIMIT FAULT UV VOUT V
LIMIT FAULT OV VOUT V
REQ UV OUT
REQ OV OUT
Values within the supported range for over and
undervoltage detection thresholds will be set to the nearest
fixed percentage. Note that the correct value for
VOUT_SCALE_LOOP must be set in the module for the
correct over or under voltage trip points to be calculated.
In addition to adjustable output voltage protection, the 12A
Digital PicoDLynx TM module can also be programmed for the
response to the fault. The VOUT_OV_FAULT RESPONSE and
VOUT_UV_FAULT_RESPONSE commands specify the
response to the fault. Both these commands use a single
data byte with the possible options as shown below.
1. Continue operation without interruption (Bits [7:6]
= 00, Bits [5:3] = xxx)
2. Continue for four switching cycles and then shut
down if the fault is still present, followed by no
restart or continuous restart (Bits [7:6] = 01, Bits
[5:3] = 000 means no restart, Bits [5:3] = 111
means continuous restart)
3. Immediate shut down followed by no restart or
continuous restart (Bits [7:6] = 10, Bits [5:3] = 000
means no restart, Bits [5:3] = 111 means
continuous restart).
4. Module output is disabled when the fault is present
and the output is enabled when the fault no longer
exists (Bits [7:6] = 11, Bits [5:3] = xxx).
Note that separate response choices are possible for output
over voltage or under voltage faults.