QBDW025A0B Datasheet, PDF (17/32 Pages) Lineage Power Corporation – 36-75Vdc Input; 12.0Vdc, 25.0A, 300W Output

GE
Data Sheet
QBDW025A0B Barracuda Series; DC-DC Converter Power Modules
36-75Vdc Input; 12.0Vdc, 25.0A, 300W Output
High Power DC specifications given in section 3.1.3 in the
SMBus specification V2.0 for the 400kHz bus speed or the
Low Power DC specifications in section 3.1.2. The complete
SMBus specification is available from the SMBus web site,
smbus.org.
PMBus Data Format
For commands that set or report any voltage thresholds
related to output voltage (including VOUT_COMMAND,
VOUT_MARGIN, POWER_GOOD and READ_VOUT), the module
supports the linear data format consisting of a two byte
value with a 16-bit, unsigned mantissa, and a fixed exponent
of -12. The format of the two data bytes is shown below:
PU: Factory set to 1. QBDW025A0B requires On/Off (I) pin to
be connected to proper input rail for module to power up.
This bit is used together with the CP, CMD and ON bits to
determine startup.
Bit Value
1
Action
Module does not power up until
commanded by the analog ON/OFF pin
and the OPERATION command as
programmed in bits [2:0] of the
ON_OFF_CONFIG register.
CMD: The CMD bit controls how the device responds to the
OPERATION command.
Bit Value
0
1
Action
Module ignores the ON bit in the
OPERATION command
Module responds to the ON bit in the
OPERATION command
The value of the number is then given by
Value = Mantissa x 2^-12
For commands that set all other thresholds, voltages or
report such quantities, the module supports the linear data
format consisting of a two byte value with an 11-bit, two’s
complement mantissa and a 5-bit, two’s complement
exponent. The format of the two data bytes is shown below:
The value is of the number is then given by
Value = Mantissa x 2 ^Exponent
PMBus Enabled On/Off
The module can also be turned on and off via the PMBus
interface. The OPERATION command is used to actually turn
the module on and off via the PMBus, while the
ON_OFF_CONFIG command configures the combination of
analog ON/OFF pin input and PMBus commands needed to
turn the module on and off. Bit [7] in the OPERATION
command data byte enables the module, with the following
functions:
0 : Output is disabled
1 : Output is enabled
This module uses the lower five bits of the ON_OFF_CONFIG
data byte to set various ON/OFF options as follows:
Bit Position
Access
Function
Default Value
4
3
2
1
0
r r/w r/w r
r
PU CMD CPR POL CPA
1
1
1
1
1
CPR: Sets Factory set to 1. QBDW025A0B requires On/Off (I)
pin to be connected to proper input rail for module to power
up. This bit is used together with the CMD, PU and ON bits to
determine startup.
Bit Value
Action
1
Module requires the analog ON/OFF pin to
be asserted to start the unit
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 both
the VIN_ON and VIN_OFF commands, possible values range
from 32.000 to 46.000V in 0.125V steps. VIN_ON must be
2.000V greater than VIN_OFF.
Both the VIN_ON and VIN_OFF commands use the “Linear”
format with two data bytes. The upper five bits [7:3] of the
high data byte form the two’s complement representation of
the exponent, which is fixed at –3 (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. The data associated with VIN_ON and
VIN_OFF can be stored to non-volatile memory using the
STORE_DEFAULT_ALL command.
PMBus Adjustable Soft Start Delay and Rise Time
The soft start delay and rise time can be adjusted in the
module via PMBus. The TON_DELAY command sets the delay
time in ms, and allows choosing delay times between 10ms
and 500ms, with resolution of 0.5ms. The TON_RISE
command sets the rise time in ms, and allows choosing soft
start times between 15ms and 500ms, with resolution of
0.5ms. When setting TON_RISE, make sure that the charging
current for output capacitors can be delivered by the module
in addition to any load current to avoid nuisance tripping of
the overcurrent protection circuitry during startup. Both the
TON_RISE and TON_DELAY commands use the “Linear”
format with two data bytes. The upper five bits [7:3] of the
May 9, 2013
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