UEI15 Series

Isolated Wide Input Range 15-Watt DC/DC Converters

www.murata-ps.com

email: sales@murata-ps.com

20 Apr 2010

MDC_UEI15W.B37 Page 11 of 14

disabled when the On/Off is grounded or brought to within a low voltage (see

Negative-polarity devices are on (enabled) when the On/Off is grounded or

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 finite time in milliseconds (see

Specifications) 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 three CAUTIONs for the On/Off Control:

CAUTION: To retain full output circuit isolation, control the On/Off from the in-

put side ONLY. If you must control it from circuits in the output, use some form

of optoisolation to the On/Off Control. This latter condition is unlikely because

the device controlling the On/Off would have to remain powered on and not be

powered from the converter.

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).

CAUTION: Do not apply voltages to the On/Off pin when there is no input

power voltage. Otherwise the converter may be permanently damaged.

Figure 7 – Driving the On/Off Control Pin (suggested circuit)

ON/OFF CONTROL

CONTROL

+ Vcc

-INPUT

Soldering Guidelines

Murata Power Solutions recommends the specifications below when installing these

converters. These specifications vary depending on the solder type. Exceeding these

specifications may cause damage to the product. Your production environment may dif-

fer; therefore please thoroughly review these guidelines with your process engineers.

Wave Solder Operations for through-hole mounted products (THMT)

For Sn/Ag/Cu based solders:

Maximum Preheat Temperature

115° C.

Maximum Pot Temperature

270° C.

Maximum Solder Dwell Time

7 seconds

For Sn/Pb based solders:

Maximum Preheat Temperature

105° C.

Maximum Pot Temperature

250° C.

Maximum Solder Dwell Time

6 seconds

On/Off Enable Control Ground Bounce Protection

To improve reliability, if you use a small signal transistor or other external

circuit to select the Remote On/Off control, make sure to return the LO side

directly to the –Vin power input on the DC/DC converter. To avoid ground

bounce errors, do not connect the On/Off return to a distant ground plane or

current-carrying bus. If necessary, run a separate small return wire directly to

the –Vin terminal. There is very little current (typically 1-5 mA) on the On/Off

control however, large current changes on a return ground plane or ground bus

can accidentally trigger the converter on or off. If possible, mount the On/Off

transistor or other control circuit adjacent to the converter.

Figure 8 – On/Off Enable Control Ground Bounce Protection

Preferred location

of On/Off control

adjacent to -Vin

terminal

DC/DC Converter

Install separate

return wire for

On/Off control

with remote

transistor

On/Off

Control

Transistor

Do not connect

control transistor

through remote

power bus

Ground plane or power return bus

+ Vin

On/Off Enable

-Vin return