PRM48BH480T250A00 Datasheet, PDF (25/44 Pages) Vicor Corporation – PRM™ Regulator

PRM48BH480 X 250A00
PIN FUNCTIONS
VC: VTM Control
+IN, -IN
Input power pins
+OUT, -OUT
This output pin is used to temporarily provide V_CC voltage to
connected VTMs during start up. The pulse is nominally 14V,
10 ms wide. A VTM can self-power once its input voltage
reaches 26V. The PRM output must be checked to make sure
it reaches this threshold voltage before the VC pulse expires.
Output power pins. Module cannot sink current.
TRIM
ENABLE
This pin turns the supply on and off. The pin is both an input
and an output and can provide the following features:
 Delayed Start: upon application of voltage (>UVLO) to the
module power input and after t_off, the ENABLE pin will
source a constant 90μA current.
 Output enable: When ENABLE is allowed to pull up above
the enable threshold, the ENABLE pin will pull up to 5.0V
with 1.8mA source capability, and the module will be
enabled.
 Output disable: ENABLE may be pulled down externally in ^‐
order to disable the module. Pull down resistance should
be less than 235Ω to SGND.
 Fault detection flag: The ENABLE 5.0V voltage source is
internally turned off when a fault condition is latched.
ENABLE control should be implemented using an open
collector configuration. It is not recommended to drive this pin
externally.
The TRIM pin is used to select the operating mode and to trim
the PRM output when Adaptive Loop operating mode is
selected. The TRIM pin has an internal pull-up to V_{CC_INT}
through a 10 kΩ resistor.
Operating Mode Select:
If TRIM is pulled below 0.45 V during the first startup after V_IN
is applied, Remote Sense / Slave operation is selected.
Otherwise, Adaptive Loop operation is selected.
This selection persists until V_IN is removed from the part, and is
not changed by fault or disable events.
Output Voltage Trim:
Sets the output voltage of the PRM in Adaptive Loop
operation.
If TRIM is permitted to pull up to 3.20 V or higher during start
up, trim is disabled, and the output is set to the nominal of 48V.
If TRIM is held between 1.00 V to 2.75 V during start up, trim
is enabled, and the output is scaled by a factor of 20 resulting
in an output voltage range of 20 V to 55 V.
This selection persists until the PRM is restarted with the
ENABLE pin, or due to fault auto-recovery.
VAUX: Auxiliary Voltage Source
AL: Adaptive Loop (Adaptive Loop operation)
Use this pin to power external devices with a non-isolated
9.0 V supply, with up to 5 mA load capability, switched with
ENABLE input. Do not place a capacitor over 0.04 µF on this
pin.
SGND: Signal Ground
This is a low current pin which provides a Kelvin connection to
the PRM’s internal signal ground. Use this pin as the ground
reference for external circuitry and signals to avoid voltage
drops caused by high currents on power returns. In array
configurations, SGND pins should be star connected at a
single point. A series resistor (~1Ω) to the star location is
recommended to decouple return currents.
This input pin allows you to set the Adaptive Loop load line.
Every volt on this pin represents 1.0 Ω of positive output slope.
There is an internal 10 kΩ pullup resistor to V_{CC_INT}. If AL is
permitted to pull up to 3.20 V or higher during start up, the
Adaptive Loop load line is disabled.
This selection persists until the PRM is restarted with the
ENABLE pin, or due to fault auto-recovery.
VT: VTM Temperature (Adaptive Loop operation)
This pin is used in the Adaptive Loop compensation algorithm
to account for the VTM output resistance variation as a
function of temperature. The VTM TM pin provides this
voltage, scaled as the temperature in K (Kelvin) divided by
100, so 25 °C is 2.98 V. Leave disconnected or pull below
1.9V to disable. The adjustment is fixed at 0.3 %/°C relative to
the value at 25 °C
- 25 -
Rev. 1.0
11/2012