GE Industrial Solutions 20A Digital MicroDLynx - Manual (Page 21)

GE
Data Sheet
20A Digital MicroDLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.45Vdc to 5.5Vdc output; 20A Output Current
April 24, 2013 ©2012 General Electric Company. All rights reserved. Page 21
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 six bits of the mantissa are fixed at 0 while the lower
five bits are programmable with a default value of 24A
(decimal). 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 ) _ _ _ (


 
 
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 Pico DLynx
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.