Feature Descriptions (continued)
Voltage Sequencing
Austin MicroLynxTM II 12V series of modules include a
sequencing feature, EZ-SEQUENCETM 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 tie the SEQ pin to VIN or leave it unconnected.
When an analog voltage is applied to the SEQ pin, the
output voltage tracks this voltage until the output reaches
the set-point voltage. The SEQ voltage must be set higher
than the set-point voltage of the module. The output
voltage follows the voltage on the SEQ pin on a one-to-one
volt basis. By connecting multiple modules together,
customers can get multiple modules to track their output
voltages to the voltage applied on the SEQ pin.
For proper voltage sequencing, first, input voltage is applied
to the module. The On/Off pin of the module is left
unconnected (or tied to GND for negative logic modules or
tied to VIN for positive logic modules) so that the module is
ON by default. After applying input voltage to the module, a
minimum of 10msec delay is required before applying
voltage on the SEQ pin. During this time, potential of 50mV
(± 10 mV) is maintained on the SEQ pin. After 10msec
delay, an analog voltage is applied to the SEQ pin and the
output voltage of the module will track this voltage on a
one-to-one volt bases until output reaches the set-point
voltage. To initiate simultaneous shutdown of the modules,
the SEQ pin voltage is lowered in a controlled manner.
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 to ensure a controlled
shutdown of the 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. For additional
guidelines on using EZ-SEQUENCETM feature of Austin
MicroLynxTM II 12V, contact your GE technical representative
for preliminary application note on output voltage
sequencing using Austin Lynx II series.