IQ32-HPC Datasheet, PDF (11/12 Pages) SynQor Worldwide Headquarters – Half-brick DC-DC Converter

PRELIMINARY
Technical
Specification
IQ32-HPC Family
Before time t₀, when the input voltage is below the UVL threshold,
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 t₁, the unit is disabled by the ON/OFF pin, and it cannot
be enabled again until the Startup Inhibit Period has elapsed.
When the ON/OFF pin goes high after t₂, the Startup Inhibit
Period has elapsed, and the output turns on within the typical
Turn-On Time.
Thermal Considerations: The maximum operating base-
plate temperature, T_B, is 100 ºC. As long as the user’s thermal
system keeps T_B < 100 ºC, the converter can deliver its full
rated power.
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, RTH_BA, of the chosen heatsink
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.
Pmax
diss
=
100
ºC
-
T_A
RTH_BA
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, Figures 3 and 4 provide Power derating curves
for an encased converter without a heatsink and with a typical
1/4" high heatsink.
Vin
Under-Voltage
Lockout Turn-
On Threshold
ON/OFF
(neg logic)
ON
OFF ON
OFF
ON
Vout
200ms
(typical start-up
inhibit period)
200ms
200ms
9ms (typical
turn on time)
t₀
t₁
t₂
t
Figure F: Startup Inhibit Period (turn-on time not to scale)
Product # IQ32xxxHPCxx
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Doc.# 005-005H332 Rev. 1
08/13/08
Page 11