GE Industrial Solutions CAR0812DC Series - Manual (Page 13)

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 13
Register
Hex
Code
Data
Byte Function
Status_mfr_specific 80 7 3.3V_fault
6 N/A
5 Interrupt
4 Fault
detected
3 PS_remote_OFF
2 DC_fault
1 INPUT_fault
0 N/A
Status_fan_1_2 81 7 Fan 1 Fault
6 Fan 2 Fault
5 N/A
4 N/A
3
Fan 1 Speed Overridden
2 Fan 2 Speed Overridden
1 N/A
0 N/A
Command Descriptions
Operation (01) : By default the Power supply is turned ON at
power up as long as Power ON/OFF signal pin is active HI. The
Operation command is used to turn the Power Supply ON or
OFF via the PMBus. The data byte below follows the
OPERATION command.
FUNCTION DATA BYTE
Unit ON 80
Unit OFF 00
To RESET the power supply cycle the power supply OFF, wait at
least 2 seconds, and then turn back ON. All alarms and
shutdowns are cleared during a restart.
Clear_faults (03): This command clears all STATUS and FAULT
registers and resets the SMBAlert# line.
If a fault still persists after the issuance of the clear_faults
command the specific registers indicating the fault are reset
and the SMBAlert# line is activated again.
WRITE_PROTECT register (10): Used to control writing to the
PMBus device. The intent of this command is to provide
protection against accidental changes. All supported
command parameters may have their parameters read,
regardless of the write_protect settings. The contents of this
register can be stored to non-volatile memory using the
Store_default_code command. The default setting of this
register is disable_all_writes except write_protect 0x80h.
FUNCTION DATA BYTE
Enable all writes 00
Disable all writes except write_protect 80
Disable all writes except write_protect and
OPERATION
40
Vout_Command (21) :
This command is used to change the
output voltage of the power supply. Changing the output
voltage should be performed simultaneously to all power
supplies operating in parallel using the Global Address
(Broadcast) feature. If only a single power supply is instructed
to change its output, it may attempt to source all the required
power which can cause either a power limit or shutdown
condition.
Software programming of output voltage permanently
overrides the set point voltage configured by the Vprog signal
pin. The program no longer looks at the ‘Vprog pin’ and will not
respond to any hardware voltage settings. If power is removed
from the µController it will reset itself into its default
configuration looking at the Vprog signal for output voltage
control. In many applications, the Vprog pin is used for setting
initial conditions, if different that the factory setting. Software
programming then takes over once I 2 C communications are
established.
Vout_OV_warn_limit (42): OV_warning is extremely useful
because it gives the system controller a heads up that the
output voltage is drifting out of regulation and the power
supply is close to shutting down. Pre-amative action may be
taken before the power supply would shut down and
potentially disable the system.
OC and OT_fault_ response (47, 50): The default response for
both OC and OT is auto_restart (hiccup). Each register,
individually, can be reconfigured into a latched state. Latched
and hiccup are the only supported states.
Restart after a latch off: Either of four restart possibilities are
available. The hardware pin Remote ON/OFF may be turned
OFF and then ON. The unit may be commanded to restart via
i2c through the Operation command by first turning OFF then
turning ON . The third way to restart is to remove and reinsert
the unit. The fourth way is to turn OFF and then turn ON ac
power to the unit. The fifth way is by changing firmware from
latch off to restart. Each of these commands must keep the
power supply in the OFF state for at least 2 seconds, with the
exception of changing to restart.
A power system that is comprised of a number of power
supplies could have difficulty restarting after a shutdown event
because of the non-synchronized behavior of the individual
power supplies. Implementing the latch-off mechanism
permits a synchronized restart that guarantees the
simultaneous restart of the entire system.
A synchronous restart can be implemented by;
1. Issuing a GLOBAL OFF and then ON command to all power
supplies,
2. Toggling Off and then ON the Remote ON/OFF signal
3. Removing and reapplying input commercial power to the
entire system.
The power supplies should be turned OFF for at least 20 – 30
seconds in order to discharge all internal bias supplies and
reset the soft start circuitry of the individual power supplies.
Auto_restart: Auto-restart is the default configuration for
recovering from over-current and over-temperature
shutdowns.
An overvoltage shutdown is followed by three attempted
restarts, each restart delayed 1 second, within a 1 minute
window. If within the 1 minute window three attempted
restarts failed, the unit will latch OFF. If less than 3 shutdowns
occur within the 1 minute window then the count for latch OFF
resets and the 1 minute window starts all over again.
Vin_UV_warn_limit (58): This is another warning flag
indicating that the input voltage is decreasing dangerously
close to the low input voltage shutdown level.