GE Industrial Solutions 12A Digital PicoDLynx - Manual (Page 16)

GE
Data Sheet
12A Digital PicoDLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.45Vdc to 5.5Vdc output; 12A Output Current
November 19, 2013
©2013 General Electric Corporation.
All rights reserved.
Page 16
Output Voltage Sequencing
The power module includes a sequencing feature, EZ-
SEQUENCE that enables users to implement various types of
output voltage sequencing in their applications. This is
accomplished via an additional sequencing pin. When not
using the sequencing feature, leave it unconnected.
The voltage applied to the SEQ pin should be scaled down by
the same ratio as used to scale the output voltage down to
the reference voltage of the module. This is accomplished by
an external resistive divider connected across the
sequencing voltage before it is fed to the SEQ pin as shown
in Fig. 44. In addition, a small capacitor (suggested value
100pF) should be connected across the lower resistor R1.
For all DLynx modules, the minimum recommended delay
between the ON/OFF signal and the sequencing signal is
10ms to ensure that the module output is ramped up
according to the sequencing signal. This ensures that the
module soft-start routine is completed before the
sequencing signal is allowed to ramp up.
Figure 44. Circuit showing connection of the sequencing
signal to the SEQ pin.
When the scaled down sequencing voltage is applied to the
SEQ pin, the output voltage tracks this voltage until the
output reaches the set-point voltage. The final value of the
sequencing voltage must be set higher than the set-point
voltage of the module. The output voltage follows the
sequencing voltage on a one-to-one basis. By connecting
multiple modules together, multiple modules can track their
output voltages to the voltage applied on the SEQ pin.
The module’s output can track the SEQ pin signal with slopes
of up to 0.5V/msec during power-up or power-down.
To initiate simultaneous shutdown of the modules, the SEQ
pin voltage is lowered in a controlled manner. The output
voltage of the modules tracks the voltages below their set-
point voltages on a one-to-one basis. A valid input voltage
must be maintained until the tracking and output voltages
reach ground potential.
Note that in all digital DLynx series of modules, the PMBus
Output Undervoltage Fault will be tripped when sequencing
is employed. This will be detected using the STATUS_WORD
and STATUS_VOUT PMBus commands. In addition, the
SMBALERT# signal will be asserted low as occurs for all faults
and warnings. To avoid the module shutting down due to the
Output Undervoltage Fault, the module must be set to
continue operation without interruption as the response to
this fault (see the description of the PMBus command
VOUT_UV_FAULT_RESPONSE for additional information).
Overcurrent Protection
To provide protection in a fault (output overload) condition,
the unit is equipped with internal current-limiting circuitry
and can endure current limiting continuously. At the point of
current-limit inception, the unit enters hiccup mode. The unit
operates normally once the output current is brought back
into its specified range.
Digital Adjustable Overcurrent Warning
Please see the Digital Feature Descriptions section.
Overtemperature Protection
To provide protection in a fault condition, the unit is
equipped with a thermal shutdown circuit. The unit will shut
down if the overtemperature threshold of 150 o C(typ) is
exceeded at the thermal reference point T
ref
.Once the unit
goes into thermal shutdown it will then wait to cool before
attempting to restart.
Digital Temperature Status via PMBus
Please see the Digital Feature Descriptions section.
Digitally Adjustable Output Over and Under Voltage
Protection
Please see the Digital Feature Descriptions section.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout limit,
the module operation is disabled. The module will begin to
operate at an input voltage above the undervoltage lockout
turn-on threshold.
Digitally Adjustable Input Undervoltage Lockout
Please see the Digital Feature Descriptions section.
Digitally Adjustable Power Good Thresholds
Please see the Digital Feature Descriptions section.
100 pF
DLynx Module
R1=Rtrim
20K
SIG_GND
SEQ
SEQ
V