GE Industrial Solutions CAR2548FP series - Manual (Page 7)

GE Data Sheet
CAR0812DC series dc-dc converter
Input: -36Vdc to -75Vdc; Output: +12 Vdc @ 850W; 3.3Vdc or 5 Vdc @ 1A
March 28, 2013 ©2013 General Electric Company. All rights reserved. Page 7
Control and Status
Control hierarchy: Some features, such as output voltage,
can be controlled both through hardware and firmware. For
example, the output voltage is controlled both by the signal
pin (Vprog) and the PMBus command, (Vout_command) .
Using output voltage as an example; the Vprog signal pin has
ultimate control of the output voltage until the Vprog is either
> 3Vdc or a no connect. When the programming signal via
Vprog is either a no connect or > 3Vdc, it is ignored, the
output voltage is set at its nominal 12Vdc and the unit output
voltage can be controlled via the PMBus command,
(Vout_command).
Analog controls: Details of analog controls are provided in
this data sheet under Signal Definitions.
Common ground: All signals and outputs are referenced to
Output return. These include ‘Vstb return’ and ‘Signal return’.
Control Signals
Voltage programming (V
prog
): An analog voltage on this
signal can vary the output voltage ± 10% from 43.2Vdc to
52.8Vdc. The equation of this signal is:
V
out
= 43.2 + 3.3 (V
prog
– 0.09) 0.09 < V
prog
< 3
If Vprog is > 3V or left open the programming signal is ignored
and the unit output is set at the setpoint of 48Vdc.
Load share (Ishare): This is a single wire analog signal that is
generated and acted upon automatically by power supplies
connected in parallel. The Ishare pins should be tied together
for power supplies if active current share among the power
supplies is desired. No resistors or capacitors should get
connected to this pin.
Remote_ON/OFF: Controls presence of the 12Vdc output
voltage. This is an open collector, TTL level control signal that
needs to be pulled HI externally through a resistor.
A turn OFF command either through this signal (Remote
ON/OFF) or firmware commanded would turn OFF the 12V
output.
Enable: This is a short signal pin that controls the presence of
the 12Vdc main output. This pin should be connected to
‘output return’ on the system side of the output connector.
The purpose of this pin is to ensure that the output turns ON
after engagement of the power blades and turns OFF prior to
disengagement of the power blades.
Write protect (WP): This signal protects the contents of the
EEPROM from accidental over writing. When left open the
EEPROM is write protected. A LO (TTL compatible) permits
writing to the EEPROM. This signal is pulled HI internally by the
power supply.
Status signals
Output current monitor (Imon): A voltage level proportional
to the delivered output current is present on this pin. The
signal level is 0. 1V per amp ± 0.25V.
AC OK: A TTL compatible status signal representing whether
the input voltage is within the anticipated range. This signal is
internally pulled HI to 3.3V via a 10kΩ resistor. A (HI) on this
signal indicates that the input voltage is applied within the
specified input range.
DC OK: A TTL compatible status signal representing
whether the output voltage is present. This signal is internally
pulled HI to 3.3V via a 10kΩ resistor. A (HI) on this signal
indicates that the output voltage is present.
Over temp warning: A TTL compatible status signal
representing whether an over temperature exists. This signal
needs to be pulled HI externally through a resistor. Open
collector (HI) on this signal indicates that temperatures are
normal.
If an over temperature should occur, this signal would pull LO
for approximately 10 seconds prior to shutting down the
power supply. The unit would restart if internal temperatures
recover within normal operational levels. At that time the
signal reverts back to its open collector (HI) state.
Fault: A TTL compatible status signal representing whether
a Fault occurred. This signal needs to be pulled HI externally
through a resistor. Open collector (HI) on this signal indicates
that no Fault is present.
This signal activates for OTP, OVP, OCP, AC fault or No output.
PS Present: This pin is connected to ‘output return’ within
the power supply. Its intent is to indicate to the system that a
power supply is present. This signal may need to be pulled HI
externally through a resistor.
Interrupt (SMBAlert#): A TTL compatible status signal,
representing the SMBusAlert# feature of the PMBus
compatible i
2 C protocol in the power supply. This signal needs
to be pulled HI externally through a resistor.
Serial Bus Communications
The I²C interface facilitates the monitoring and control of
various operating parameters within the unit and transmits
these on demand over an industry standard I²C Serial bus.
All signals are referenced to ‘Signal Return’.
Device addressing: The microcontroller (MCU) and the
EEPROM have the following addresses:
Device Address Address Bit Assignments
(Most to Least Significant)
MCU 0xBx 1 0 1 1 A2 A1 A0 R/W
Broadcast 0x00 0 0 0 0 0 0 0 0
EEPROM
0xAx 1 0 1 0 A2 A1 A0 R/W
The Global Broadcast instruction executes a simultaneous
write instruction to all power supplies. A read instruction
cannot be accessed globally. The three programmable
address bits are the same for all I
2 C accessible devices within
the power supply.
Address lines (A2, A1, A0): These signal pins allow up to eight
(8) modules to be addressed on a single I²C bus. The pins are
pulled HI internal to the power supply. For a logic LO these
pins should be connected to ‘Output Return’
Serial Clock (SCL): The clock pulses on this line are generated
by the host that initiates communications across the I²C
Serial bus. This signal is pulled up internally to 3.3V by a 10kΩ