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

PD-97309A
HIGH RELIABILITY
DC/DC CONVERTER
HTA-SERIES
200V Input, Single/Dual Output
Description
The HTA Series of DC/DC converters is a family of 20W,
single and dual output, high reliability devices designed to
operate in extremely high temperature environments such as
those encountered in oil exploration applications. Features
include small size, low weight and high tolerance to
environmental stresses such as wide temperature extremes,
severe shock and vibration. All internal components are
derated to meet the intended operating environment.
Documentation including electrical stress and thermal analysis
are available.
The converters incorporate a fixed frequency single forward
topology with magnetic feedback and internal EMI filter. All
models include an external inhibit port and have an adjustable
output voltage. They are enclosed in a hermetic 1.5" x 4.0" x
0.430" AlSi package and weigh less than 70grams. The
package utilizes rugged ceramic feed-thru copper core pins
and is sealed using parallel seam welding.
Full environmental screening includes temperature cycling,
constant acceleration, fine and gross leak, and burn-in. Non-
screened versions of the HTA converters are available for
system development purposes. Variations in electrical
specifications and screening to meet custom requirements
can be accommodated.
Circuit Description
The HTA series of converters utilize a single-ended forward
topology with resonant reset. The nominal switching frequency
is 500KHz. 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 in the
event of an internal control loop failure. This mechanism
limits the maximum output voltage to approximately 20% over
the nominal regardless of the line voltage.
Output current is limited under any load fault condition to
approximately 125% of rated load at maximum operating case
temperature. 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.
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Features
n 150 to 250V DC Input Range
n Up to 20W Output Power
n Single and Dual Output Models Include
3.3, 5, 12, 15, ±5, ±12 and ±15V
n Internal EMI Filter
n Magnetically Coupled Feedback
n High Efficiency - to 76%
n -35°C to +185°C Operating Case Temperature Range
n 10MΩ @ 500VDC Isolation
n Under-Voltage Lockout
n Short Circuit and Overload Protection
n Output Over Voltage Limiter
n Adjustable Output Voltage
n Synchronization Input and Output
n External Inhibit
n Low Weight, < 70grams
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 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 4.0V with respect to the Input Return (pin 2).
The output voltage of all models can be adjusted using
a single external resistor.
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03/03/09