M3L2005S Datasheet, PDF (2/13 Pages) International Rectifier – HYBRID-HIGH RELIABILITY RADIATION TOLERANT DC-DC CONVERTER

M3L-SERIES
(+28V Input, Single/Dual Output)
Circuit Description
The M3L-Series converters utilize a single-ended forward
topology with resonant reset. The nominal switching frequency is
500 kHz. Electrical isolation and tight output regulation are
achieved through the use of a magnetically coupled feedback.
Voltage feed-forward with duty factor limiting provides high
line rejection.
An internal EMI filter allows the converter to meet the
conducted emissions requirements of MIL-STD-461C on
the input power leads. A single-stage output filter reduces
the typical output ripple to less than 50mV peak-to-peak.
Output current is limited under any load fault condition to
approximately 125% of rated. An overload condition causes
the converter output to behave like a constant current
source with the output voltage dropping below nominal.
The converter will resume normal operation when the load
current is reduced below the current limit point. This
protects the converter from both overload and short circuit
conditions. The current limit point exhibits a slightly
negative temperature coefficient to reduce the possibility
of thermal runaway.
An external inhibit port is provided to control converter
operation. The converter’s operation is inhibited when
this pin is pulled low. It is intended to be driven by an
open collector logic device. The pin may be left open for
normal operation and has a nominal open circuit voltage
of 10.5V with respect to the input return (pin 2).
The output voltage of all models can be adjusted using a
single external resistor.
Design Methodology
The M3L-Series was developed using a proven conservative
design methodology which includes selecting radiation
tolerance and established reliability components and fully
de-rating to the requirements of MIL-STD-975 and MIL-STD-
1547. Heavy de-rating of the power MOSFET gate and
drain voltages minimize the possibility of SEGR and
SEB. A magnetic feedback circuit is utilized instead of
opto-couplers to minimize temperature, radiation and
aging sensitivity. PSPICE was used extensively to
predict and optimize circuit performance for both beginning and
end-of-life. Thorough design analyses include Radiation
Susceptibility (TREE), Stress, Thermal, and Reliability
(MTBF).
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2016-09-21