GE Industrial Solutions CAR0812DC Series - Manual (Page 9)

GE Data Sheet
CAR0812DC Series DC-DC Converter
Input: -36V
DC
to -75V
DC
; Output: +12 V
DC
@ 850W; 3.3V
DC
or 5 V
DC
@ 1A
April 23, 2013 ©2013 General Electric Company. All rights reserved. Page 9
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 (Vprog): An analog voltage on this
signal can vary the output voltage ± 10% of nominal, from
10.8V
DC
to 13.2V
DC
. The equation of this signal is:
V
OUT
= 10.8  (Vprog * 0.96) where Vprog = 0 to 2.5V
DC
Between 2.5 and 3V the output stays at 13.2V
DC
. If Vprog is >
3V, or left open, the programming signal is ignored and the
unit output is set at the setpoint of 12V
DC
.
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 12V
DC
output
voltage. A logic LO on this signal pin turns OFF the 12V
DC
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 0.04V per amp ± 0.25V.
Input_OK: A TTL compatible status signal representing
whether the input voltage is within the anticipated range. This
signal needs to be pulled HI externally through a resistor.
DC_OK: A TTL compatible status signal representing whether
the output voltage is present. This signal needs to be pulled HI
externally through a resistor.
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.
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.
This signal activates for OTP, OVP, OCP, INPUT 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
resistor. The end user should add additional pull up resistance
as necessary to ensure that rise and fall time timing and the
maximum sink current is in compliance to the I²C
specifications.