HTH27022S_15 Datasheet, PDF (1/14 Pages) International Rectifier – HIGH RELIABILITY DC-DC CONVERTER

PD-97815
HIGH RELIABILITY
DC-DC CONVERTER
HTH27022S
165°C, 270V Input, 55W, 22V Single Output
Description
The HTH27022S is a single output 55W DC-DC converter
designed to operate in extremely high temperature environments
such as those encountered in oil exploration. Features include
small size, low weight and high tolerance to environmental
stresses such as wide wide temperature extremes, severe
shock and vibration. All internal components and assembly
processes have been selected and developed to ensure reliable
performance in the intended operating environments.
The converter incorporates a fixed frequency forward topology
with magnetic feedback and internal EMI filter. It also includes
an external inhibit port and have an adjustable output voltage.
It is enclosed in a hermetic 4.0" x 2.15" x 0.40" (3.5"x1.5"x0.40"H
excluding mounting tabs and I/O pins) AlSi package and weighs
less than 70 grams. The package utilizes rugged ceramic
feed-thru, copper-cored pins and is sealed using laser welding.
Full environmental screening includes temperature cycling,
constant acceleration, fine and gross leak, and burn-in. Please
refer to Device Screening table. Variations in electrical
specifications and screening to meet custom requirements
can be accommodated
HTH
Features
n 190 to 400V DC Input Range
n Up to 55W Output Power
n 22V, 2.5A Rated Output Voltage and Current
n Internal EMI Filter
n Magnetically Coupled Current Feedback
n 80% Minimum Efficiency
n -20°C to +165°C continuous with transient up to +175°C
n 100MΩ @ 500V DC Isolation
n Under-Voltage Lockout
n Short Circuit and Overload Protection
n Output Over Voltage Limiter
n Adjustable Output Voltage within 10% of nominal
n External Inhibit
n Low Weight < 70 grams
Circuit Description
The HTH27022S converter utilizes an enhanced forward
topology with two power switches and resonant reset. The
nominal switching frequency is 520 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 and protection against
output over voltage due to certain component failures in the
internal control loop. This mechanism limits the maximum
output voltage to approximately 20% over the nominal
regardless of the line voltage with an output load that is
≥ 25% of the full rated output power.
Output current is limited under load fault conditions to
approximately 125% of the rating. 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.
www.irf.com
Applications
n Down Hole Exploration Tools
The current limit point exhibits a slightly negative
temperature coefficient to reduce the possibility of
thermal runaway.
An external inhibit port (Pin 4) is provided to control
converter operation. The converter’s operation is
inhibited when this pin is pulled low. It is designed 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 4V with respect to the input
return (Pin 2).
The output voltage of all models can be adjusted using
a single external resistor within ±10% of nominal output
voltage.
1
10/15/13