Preliminary Data Sheet
TM
: Non-Isolated DC-DC Power Modules
4.5Vdc – 5.5Vdc input; 0.8Vdc to 3.63Vdc output; 30A Output Current
6Vdc – 14Vdc input; 0.8Vdc to 3.63Vdc output; 20/30A Output Current
2016 General Electric Company. All rights reserved. Page
Voltage Margining
Output voltage margining can be implemented in the Austin
MegaLynxTM modules by connecting a resistor, Rmargin-up,
from the Trim pin to the ground pin for margining-up the
output voltage and by connecting a resistor, Rmargin-down,
from the Trim pin to output pin for margining-down. Figure
53 shows the circuit configuration for output voltage
margining. The POL Programming Tool, available at
www.gecriticalpower.com under the Design Tools section,
also calculates the values of Rmargin-up and Rmargin-down for a
specific output voltage and % margin. Please consult your
local GE technical representative for additional details.
Figure 53. Circuit Configuration for margining Output
voltage.
Voltage Sequencing
The Austin MegaLynxTM series of modules include a
sequencing feature 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, either leave the SEQ pin
unconnected or tied to VIN.
For proper voltage sequencing, first, input voltage is applied
to the module. The On/Off pin of the module is or tied to
GND so that the module is ON by default. After applying
input voltage to the module, a delay of 10msec minimum is
required before applying voltage on the SEQ pin. During this
delay time, the SEQ pin should be kept at a voltage of 50mV
(± 20 mV). After the 10msec delay, the voltage applied to the
SEQ pin is allowed to vary and the output voltage of the
module will track this voltage on a one-to-one volt basis
until the output reaches the set-point voltage. To initiate
simultaneous shutdown of the modules, the SEQ pin voltage
is lowered in a controlled manner. The output voltages of
the modules track the sequence pin voltage when it falls
below their set-point voltages. A valid input voltage must be
maintained until the tracking and output voltages reach
zero to ensure a controlled shutdown of the modules. For a
more detailed description of sequencing, please refer to
Application Note AN04-008 titled “Guidelines for
Sequencing of Multiple Modules”.
When using the EZ-SEQUENCETM feature to control start-up
of the module, pre-bias immunity feature during start-up is
disabled. The pre-bias immunity feature of the module
relies on the module being in the diode-mode during start-
up. When using the EZ-SEQUENCETM feature, modules goes
through an internal set-up time of 10msec, and will be in
synchronous rectification mode when voltage at the SEQ pin
is applied. This will result in sinking current in the module if
pre-bias voltage is present at the output of the module.
When pre-bias immunity during start-up is required, the EZ-
SEQUENCETM feature must be disabled.
Active Load Sharing (-P Option)
For additional power requirements, the Austin MegaLynx
series power module is also available with a parallel option.
Up to five modules can be configured, in parallel, with active
load sharing. Good layout techniques should be observed
when using multiple units in parallel. To implement forced
load sharing, the following connections should be made:
• The share pins of all units in parallel must be connected
together. The path of these connections should be as
direct as possible.
• All remote-sense pins should be connected to the
power bus at the same point, i.e., connect all the
SENSE(+) pins to the (+) side of the bus. Close proximity
and directness are necessary for good noise immunity
Some special considerations apply for design of converters
in parallel operation:
• When sizing the number of modules required for
parallel operation, take note of the fact that current
sharing has some tolerance. In addition, under
transient condtions such as a dynamic load change
and during startup, all converter output currents will
not be equal. To allow for such variation and avoid the
likelihood of a converter shutting off due to a current
overload, the total capacity of the paralleled system
should be no more than 75% of the sum of the
individual converters. As an example, for a system of
four ATS030A0X3-SR converters the parallel, the total
Vo
Austin Lynx or
Lynx II Series
GND
Trim
Q1
Rtrim
Rmargin-up
Q2
Rmargin-down