F
EATURES
•
•
•
•
•
–40°C to +85°C operation
16 to 32 VDC input voltage
Fully isolated
Opto-coupler feedback
Switching frequency
Single and dual outputs
typical 80 kHz, variable freq.
Triple output 200 kHz, fixed
Topology – Flyback
Inhibit function
Indefinite short circuit protection
Up to 75% efficiency
Requires external capacitors
DC/DC C
ONVERTERS
28 V
OLT
I
NPUT
HR40 SERIES
4 WATT
MODELS
VDC O
UTPUT
SINGLE
DUAL
TRIPLE
5
±12
+5 & ±12
±15
+5 & ±15
•
•
•
•
•
Size (max.): 1.075 x 1.075 x 0.370 inches (27.31 x 27.31 x 9.40 mm)
See Section B8, case C2, for dimensions.
Weight:
20 grams maximum
Screening: Standard only. See Section C2 for screening description.
DESCRIPTION
The HR40 Series™ DC/DC converters offer the high efficiencies
associated with switching regulators, yet have full isolation of input
and output grounds. The units are built using thick-film hybrid tech-
nology and are sealed in metal packages for high-reliability applica-
tions. All models are guaranteed to pass a gross leak test (maximum
leak rate of 1 x 10
-3
atm-cc/sec).
The HR40 Series devices are flyback energy storage switching
regulators which require a minimum of components resulting in
small package size. Single and dual models self-oscillate at an
operating frequency which is an approximate inverse function of the
load. At full load, the frequency is typically 80 kHz for single and dual
output models. Triple output models operate at a fixed frequency of
approximately 200 kHz. A transformer in the forward power circuit
and an opto-coupler in the feedback/control loop maintain input to
output isolation.
Models are available with single 5 volt, dual 12 or 15 volt, or triple
(+5 and either ±12 or ±15) outputs with an input voltage range of 16
to 32 VDC. Output power of up to 4 watts is available from the dual
output models for either balanced or unbalanced loads; however, at
least 25% of the total load should be on the positive output. The
single output device can provide 3.5 watts, and the triple output can
supply up to 3.2 watts. The high efficiency is almost constant over
the entire input voltage range and from approximately 25% of full
load to full load. This makes the unit ideal for battery applications.
An open collector TTL inhibit is provided to allow power shutdown
and startup from a logic input. An open circuit on the inhibit terminal
(pin 15) gives normal operation, and a TTL low level shuts down the
converter. The inhibit pin has an open circuit voltage of 12 to 28 V.
Input current in the shutdown mode will be less than 15 mA. Current
limiting is provided on each output for indefinite short circuit protec-
tion.
Due to the high efficiency, heat sinking requirements are minimized,
but consideration should be given to removing self-generated heat
when operating these devices at maximum ratings. To increase
dissipation, heat conducting material (PCB, copper sheet, heat sink,
etc.) should be brought into contact with the converter’s baseplate.
The converter can be operated at full load at a case temperature of
85°C, with the output power derated linearly to zero at 105°C.
W
ARNING
: E
XTERNAL
C
APACITORS
R
EQUIRED
External capacitors are required on the outputs.
Operating the unit
without external capacitors will result in damage to the internal
circuitry.
Minimum recommended capacitor values are given in
Tables 1 and 2. For optimum performance, low ESR (Equivalent
Series Resistance) solid tantalum capacitors are required. The
specifications on the following pages are based on the use of high-
quality solid tantalums. Operation with different types of capacitors
will seriously affect performance.
B4-51
CRANE [ Crane Aerospace & Electronics. ]
