GE Industrial Solutions 40A Digital MegaDLynx - Manual (Page 18)

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 18
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 with a default value of 55.5A (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 40A
Digital Mega 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.
PMBus Adjustable Input Undervoltage Lockout
The module allows adjustment of the input under voltage
lockout and hysteresis. The command VIN_ON allows setting
the input voltage turn on threshold, while the VIN_OFF
command sets the input voltage turn off threshold. For the
VIN_ON command, possible values are 3.5 to 14V in 0.5V
steps. For the VIN_OFF command, possible values are 3V to
14V in 0.5V steps. If other values are entered for either
command, they will be mapped to the closest of the allowed
values.
Both the VIN_ON and VIN_OFF commands use the “Linear”
format with two data bytes. The upper five bits represent the
exponent (fixed at -2) and the remaining 11 bits represent
the mantissa. For the mantissa, the four most significant bits
are fixed at 0.