Specifi cation Notes:
(1) All models are tested and specifi ed with external 1 µF paralleled with 10 µF output capacitors
and no external input capacitor. All capacitors are low ESR types. These capacitors are necessary to
accommodate our test equipment and may not be required to achieve specifi ed performance in your
applications. All models are stable and regulate within spec under no-load conditions.
All specifi cations are typical unless noted. General conditions for Specifi cations are +25°C,
Vin=nominal, Vout=nominal, full load. Adequate airfl ow must be supplied for extended testing under
power.
(2) Input Back Ripple Current is tested and specifi ed over a 5 Hz to 20 MHz bandwidth. Input fi ltering
is Cin=33 µF, 100V, Cbus=220 μF, 100V, Lbus=12 µH.
(3) Note that Maximum Power Derating curves indicate an average current at nominal input voltage.
At higher temperatures and/or lower airfl ow, the DC/DC converter will tolerate brief full current outputs
if the total RMS current over time does not exceed the Derating curve. All Derating curves are pre-
sented at sea level altitude. Be aware of reduced power dissipation with increasing altitude.
(4) Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method 1, Case 3,
ground fi xed conditions, Tpcboard=+25°C, full load, natural air convection.
(5) The On/Off Control is normally selected by a switch or an open collector or open drain transistor.
But it may also be driven with external logic or by applying appropriate external voltages which are
referenced to Input Common and comply with the On/Off voltage specifi cations.
(6) Output current limiting begins when the output voltage degrades approximately 2% from the
selected setting.
(7) The outputs are not intended to sink appreciable reverse current.
(8) Output noise may be further reduced by adding an external fi lter. Logic circuits with low power
voltages may have a small voltage margin between logic ZERO and logic ONE, requiring noise sup-
pression. Use only as much output fi ltering as needed to achieve your noise requirements. Excessive
output capacitance can retard transient response or possibly cause instability. Low ESR ceramic
capacitors may degrade dynamic performance. Be sure to thoroughly test your system under full load
with all components installed.
(9) All models are fully operational and meet published specifi cations, including “cold start” at –40°C.
At full power, the package temperature of all on-board components must not exceed +128°C.
(10) Regulation specifi cations describe the deviation as the line input voltage or output load current is
varied from a nominal midpoint value to either extreme.
(11) The output overvoltage protection is automatic recovery. The overvoltage may occur either from
internal failure or from an external forcing voltage as in a shared power system.
(12) Output current limit and short circuit protection is non-latching. When the overcurrent fault is
removed, the converter will immediately recover. After an output overcurrent or short circuit, “hiccup”
operation repeatedly attempts to restart the converter with a brief, full-current output. If the overcurrent
condition still exists, the restart current will be removed and then tried again. This short current pulse
prevents overheating and damaging the converter. Once the fault is removed, the converter immedi-
ately resumes normal operation.
(13) Do not exceed maximum power specifi cations when adjusting the output trim.
(14) At zero output current, the output may contain low frequency components which exceed the
ripple specifi cation. The output may be operated indefi nitely with no load.
(15) If reverse polarity is accidentally applied to the input, to ensure reverse input protection with full
output load, always connect an external input fuse in series with the +Vin input. Use approximately
twice the full input current rating with nominal input voltage.
(16) Output accuracy is dependent on user-supplied trim resistors. To achieve high accuracy, use ±1%
or better tolerance metal-fi lm resistors mounted close to the converter.
(17) Normally, the Sense lines are connected at the remote load to compensate for IR voltage drops
in the power wiring and to improve dynamic response. If Sense is not used, each Sense pin should be
connected at the converter to its respective Vout pin.
CAUTION: This product is not internally fused. To comply with safety agency certifi cations and to
avoid injury to personnel or equipment, the user must connect an external fast-blow fuse to the input
terminals.
Input Voltage:
D24 Models - Volts, max. continuous 0-36 VDC
Volts, transient, 100 mSec 50 VDC
D48 Models - Volts, max. continuous 0-75 VDC
Volts, transient, 100 mSec 100 VDC
On/Off Control -0.7 V. min to +15V max.
Input Reverse-Polarity Protection None. Install external fuse.
Output Overvoltage Vout nom. +20% max.
Output Current Current-limited. Devices can
withstand sustained short
circuit without damage. The
outputs are not intended to
accept appreciable reverse
current.
Overtemperature Protection Device includes electronic
overtemperature shutdown
protection under normal
operation.
Storage Temperature -55 to +125° C
Lead Temperature See soldering specifi cations
These are stress ratings. Exposure of devices to greater than any of these conditions may
adversely affect long-term reliability. Proper operation under conditions other than those
listed in the Performance/Functional Specifi cations Table is not implied.
Absolute Maximum Ratings
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Single Output UCH Models
Isolated, “Half-Brick”
1.8−15V Output DC/DC Converters
MDC_UCH Models.C01 Page 8 of 18
