Technical Specification
Quarter
24V 15V
6.7A
out
in
Brick
STARTUP INHIBIT PERIOD
Figure F shows three turn-on scenarios, where a Startup
Inhibit Period is initiated at t0, t1, and t2:
The Startup Inhibit Period ensures that the converter will
remain off for at least 200ms when it is shut down for any
reason. When an output short is present, this generates a
5Hz "hiccup mode," which prevents the converter from over-
heating. In all, there are seven ways that the converter can
be shut down, initiating a Startup Inhibit Period:
Before time t0, when the input voltage is below 16V (typ.),
the unit is disabled by the Input Under-Voltage Lockout fea-
ture. When the input voltage rises above 16V, the Input
Under-Voltage Lockout is released, and a Startup Inhibit
Period is initiated. At the end of this delay, the ON/OFF pin
is evaluated, and since it is active, the unit turns on.
• Input Under-Voltage Lockout
• Input Over-Voltage Shutdown (not present in Quarter-
brick)
At time t1, the unit is disabled by the ON/OFF pin, and it
cannot be enabled again until the Startup Inhibit Period has
elapsed.
• Output Over-Voltage Protection
• Over Temperature Shutdown
• Current Limit
When the ON/OFF pin goes high after t2, the Startup Inhibit
Period has elapsed, and the output turns on within the 4ms
(typ.) "Turn On Time."
• Short Circuit Protection
• Turned off by the ON/OFF input
V
in
Under-Voltage
Lockout Turn-On
Threshold
ON/OFF
(pos logic)
ON
OFF ON
OFF
ON
V
4ms (typical
turn on time)
out
200ms
(typical start-up
inhibit period)
200ms
200ms
t
t0
t1
t2
Figure F: Startup Inhibit Period (turn-on time not to scale)
Product # PQ24150QGA07
Phone 1-888-567-9596
Doc.# 005-2QG215D_A
3/1/02
Page 12
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