cf48240qtc06nrs-g SynQor Worldwide Headquarters, cf48240qtc06nrs-g Datasheet - Page 15

• Manufacturer Part Number: cf48240qtc06nrs-g
• Description: Quarter-brick Dc-dc Converter
• Manufacturer: SynQor Worldwide Headquarters

Product # CF48xxxQTXxx
Startup Inhibit Period: The Startup Inhibit Period ensures that
the converter will remain off for approximately 200 ms when it is
shut down for any reason. When an output short is present, this
generates a 5 Hz “hiccup mode,” which prevents the converter
from overheating. In all, there are seven ways that the converter
can be shut down, initiating a Startup Inhibit Period:
• Input Under-Voltage Lockout
• Input Over-Voltage Lockout
• Output Over-Voltage Protection
• Over Temperature Shutdown
• Current Limit
• Short Circuit Protection
• Turned off by the ON/OFF input
Figure E shows three turn-on scenarios, where a Startup Inhibit
Period is initiated at t
Before time t
the unit is disabled by the Input Under-Voltage Lockout feature.
When the input voltage rises above the UVL threshold, 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.
At time t
be enabled again until the Startup Inhibit Period has elapsed.
Under-Voltage
Lockout Turn-
On Threshold
ON/OFF
(neg logic)
1
, the unit is disabled by the ON/OFF pin, and it cannot
V out
V in
0
, when the input voltage is below the UVL threshold,
ON
t
0
0
, t
(typical start-up
inhibit period)
1
, and t
200ms
Phone [phone]
2
:
Figure E: Startup Inhibit Period (turn-on time not to scale)
t
1
www.synqor.com
OFF
200ms
ON
When the ON/OFF pin goes high after t
Period has elapsed, and the output turns on within the typical
Turn-On Time.
Thermal Considerations: The maximum operating base-plate
temperature, T
keeps T
A power derating curve can be calculated for any heatsink that is
attached to the base-plate of the converter. It is only necessary
to determine the thermal resistance, R
between the base-plate and the ambient air for a given airflow
rate. This information is usually available from the heatsink
vendor. The following formula can the be used to determine the
maximum power the converter can dissipate for a given thermal
condition if its base-plate is to be no higher than 100 ºC.
This value of power dissipation can then be used in conjunction
with the data shown in Figure 2 to determine the maximum load
current (and power) that the converter can deliver in the given
thermal condition.
For convenience, power derating curves for an encased converter
without a heatsink and with a typical heatsink are provided for
each output voltage.
B
t
2
OFF
< 100 ºC, the converter can deliver its full rated power.
Doc.# 005-0005450 Rev. B
200ms
B
, is 100 ºC. As long as the user’s thermal system
P
diss
max
=
ON
100 ºC - T
R
TH BA
9ms
turn on time)
CF48xxxQTxxx
Specification
(typical
A
TH BA
05/11/10
Technical
, of the chosen heatsink
2
, the Startup Inhibit
t
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