F
EATURES
•
•
•
•
•
•
•
-55°C to +125°C operation
12 to 50 VDC input
Fully isolated
Magnetic feedback
Fixed frequency 370 kHz typ.
Topology – Current Mode Flyback
80 V for up to 120 ms transient protection
(70 V for 15 V single and dual models)
• Inhibit function
• Short circuit protection
• Undervoltage lockout
DC/DC C
ONVERTERS
28 V
OLT
I
NPUT
MCH SERIES
1.5 WATT
MODELS
VDC O
UTPUT
SINGLES
5
5.2
12
15
DUALS
±5
±12
±15
Size (max.): 0.980 x 0.805 x 0.270 inches (24.89 x 20.45 x 6.86 mm)
Weight:
12 grams max.
Screening: Standard, ES, or 883 (Class H)
DESCRIPTION
With a miniature footprint of just 0.8 square inches, the MCH
Series™ of DC/DC converters delivers 1.5 watts of output power
while saving significant board real estate. The wide input voltage
range of 12 to 50 VDC accepts the varying voltages of military, aero-
space, or space bus power and tightly regulates output voltages to
protect downstream components. Transient protection of 80 volts for
up to 120 milliseconds exceeds the requirements of MIL-STD-704A
for the 5, 5.2, and 12 volt single models and the 12 volt dual model.
The 15 volt single and dual converters will withstand transients of up
to 70 volts for up to 120 milliseconds.
I
NHIBIT
F
UNCTION
When an open collector TTL logic low is applied to the inhibit
terminal, pin 7, the converter shuts down and lowers the output
voltage to near zero and input current to as low as 2.3 mA. Leaving
the terminal open or applying an open collector TTL logic high will
enable the converter.
P
ROTECTION
F
EATURES
Undervoltage lockout prevents the MCH Series converters from
operating below approximately 8 VDC input voltage to keep system
current levels smooth, especially during initialization or re-start oper-
ations. All models include a soft-start function to prevent large
current draw and minimize overshoot. The converters also provide
short circuit protection by restricting the current.
C
ONVERTER
D
ESIGN
MCH Series DC/DC converters incorporate a continuous flyback
topology with a constant switching frequency of approximately 370
kHz. Current-mode pulse width modulation (PWM) provides output
voltage regulation. Output error voltage is magnetically fed back to
the input side of the PWM to regulate output voltage. Regulation is
also affected by the load; refer to the Electrical Characteristics
tables on the following pages.
Dual models regulate the negative output with magnetic coupling to
the positive output. Up to 80% of the total load may be on one output
providing that the other output carries a minimum of 20% of the total
load. The dual models can be used at double the output voltage by
connecting the load between positive and negative outputs, leaving
the common unconnected. (ex: MCH2805D can be used as a 10
VDC output.)
POSITIVE 1
INPUT
MIL-STD-461
Use Interpoint’s FMSA-461 EMI filter to pass the CE03 requirements
of MIL-STD-461C.
C
ONVENIENT
P
ACKAGING
The MCH Series converters are packaged in hermetically sealed,
projection-welded metal cases which provide EMI/RFI shielding.
+
0.47
µF
typical
+V
IN
FB
+
3 POSITIVE
OUTPUT
INHIBIT
7
SHUTDOWN
PWM
CONTROLLER
+V
OUT
+
4 OUTPUT
COMMON
6 NEGATIVE
OUTPUT
DUAL MODELS ONLY
INPUT
COMMON
2
F
IGURE
1: B
LOCK
D
IAGRAM
1
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
