FGSD12SR6003A Datasheet, PDF (14/41 Pages) List of Unclassifed Manufacturers – 3-14.4Vdc Input, 3A, 0.45-5.5Vdc Output

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FGSD12SR6003*A
3-14.4Vdc Input, 3A, 0.45-5.5Vdc Output
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/w r/w r/w r/w r
PU CMD CPR POL CPA
1
0
1
1
1
PU: Sets the default to either operate any time input
power is present or for the ON/OFF to be controlled
by the analog ON/OFF input and the PMBus
OPERATION command. This bit is used together
with the CP, CMD and ON bits to determine startup.
Bit Value
0
1
Action
Module powers up any time power is
present regardless of state of the analog
ON/OFF pin
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
CPR: Sets the response of the analog ON/OFF pin.
This bit is used together with the CMD, PU and ON
bits to determine startup.
Bit Value
0
1
Action
Module ignores the analog ON/OFF pin,
i.e. ON/OFF is only controlled through the
PMBUS via the OPERATION command
Module requires the analog ON/OFF pin
to be asserted to start the unit
Preliminary Data Sheet
PMBus Adjustable Soft Start Rise Time
The soft start rise time can be adjusted in the module
via PMBus. When setting this parameter, 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. The TON_RISE
command sets the rise time in ms, and allows
choosing soft start times between 600us and 9ms,
with possible values listed in Table 5. Note that the
exponent is fixed at -4 (decimal) and the upper two
bits of the mantissa are also fixed at 0.
Table 5
Rise Time
600us
900us
1.2ms
1.8ms
2.7ms
4.2ms
6.0ms
9.0ms
Exponent
11100
11100
11100
11100
11100
11100
11100
11100
Mantissa
00000001010
00000001110
00000010011
00000011101
00000101011
00001000011
00001100000
00010010000
Output Voltage Adjustment Using the
PMBus
The VOUT_SCALE_LOOP parameter is important for
a number of PMBus commands related to output
voltage trimming, margining, over/under voltage
protection and the PGOOD thresholds. The output
voltage of the module is set as the combination of the
voltage divider formed by RTrim and a 20kΩ upper
divider resistor inside the module, and the internal
reference voltage of the module. The reference
voltage V_REF is nominally set at 600mV, and the
output regulation voltage is then given by
V_OUT



20000  RTrim
RTrim



V_REF
Hence the module output voltage is dependent on the
value of RTrim which is connected external to the
module. The information on the output voltage divider
ratio is conveyed to the module through the
VOUT_SCALE_LOOP parameter which is calculated
as follows:
VOUT
_ SCALE
_
LOOP

RTrim
20000  RTrim
The VOUT_SCALE_LOOP parameter is specified
using the “Linear” format and two bytes. The upper
five bits [7:3] of the high byte are used to set the
exponent which is fixed at –9 (decimal). The
remaining three bits of the high byte [2:0] and the
eight bits of the lower byte are used for the mantissa.
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Ver 1.6 May. 8, 2013