Datasheet
Remote On/Off Control
On the input side, a remote On/Off Control can be ordered with either logic
type.
Positive: Standard models are enabled when the On/Off pin is left open or
is pulled high to +Vin with respect to –Vin. An internal bias current causes the
open pin to rise to approximately +15V. Some models will also turn on at lower
intermediate voltages (see Specifi cations). Positive-logic devices are disabled
when the On/Off is grounded or brought to within a low voltage (see Specifi ca-
tions) with respect to –Vin.
Negative: Optional negative-logic devices are on (enabled) when the On/Off
is grounded or brought to within a low voltage (see Specifi cations) with respect
to –Vin. The device is off (disabled) when the On/Off is left open or is pulled
high to approximately +15V with respect to –Vin.
Dynamic control of the On/Off function should be able to sink appropriate
signal current when brought low and withstand appropriate voltage when
brought high. Be aware too that there is a fi nite time in milliseconds (see
Specifi cations) between the time of On/Off Control activation and stable,
regulated output. This time will vary slightly with output load type and current
and input conditions.
There are several CAUTIONs for the On/Off Control:
CAUTION: While it is possible to control the On/Off with external logic if
you carefully observe the voltage levels, the preferred circuit is either an open
drain/open collector transistor, a switch or a relay (which can thereupon be
controlled by logic) returned to negative Vin.
CAUTION: Do not apply voltages to the On/Off pin when there is no input
power voltage. Otherwise the converter may be permanently damaged.
Output Capacitive Load
These converters do not require external capacitance added to achieve rated
specifi cations. Users should only consider adding capacitance to reduce switch-
ing noise and/or to handle spike current step loads. Install only enough ca-
pacitance to achieve noise objectives. Excess external capacitance may cause
regulation problems, slower transient response and possible instability. Proper
wiring of the Sense inputs will improve these factors under capacitive load.
The maximum rated output capacitance and ESR specifi cation is given for a
capacitor installed immediately adjacent to the converter. Any extended output
wiring or smaller wire gauge or less ground plane may tolerate somewhat high-
er capacitance. Also, capacitors with higher ESR may use a larger capacitance.
Product Adaptations
Murata Power Solutions offers several variations of our core product family.
These products are available under scheduled quantity orders and may also
include separate manufacturing documentation from a mutually-agreeable
Product Specifi cation. Since these product adaptations largely share a common
parts list, similar specifi cations and test methods with their root products, they
are provided at excellent costs and delivery. Please contact MPS for details.
As of this date, the following products are available:
UCH-3.3/30-D48NBHL2-Y
UCH-5/10-D48NBHL2-Y
UCH-3.3/15-D48NBHL2-Y
UCH-3.3/35-D24NBHL2-Y
These are all negative On/Off logic, baseplate installed, conformal coating
added, 3.68mm pin length, and RoHS-5 hazardous substance compliance (with
lead).
www.murata-ps.com/support
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without
notice. © 2014 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
Single Output UCH Models
Isolated, “Half-Brick”
1.8−15V Output DC/DC Converters
MDC_UCH Models.C01 Page 18 of 18