UWE Series

Wide Input, Isolated

Eighth-Brick DC/DC Converters

www.murata-ps.com

Positive-polarity models (“P" part-number suffix) are enabled when the

On/Off Control is left open or is pulled high, as per Figure 4. Positive-polarity

devices are disabled when the On/Off Control is pulled low.

Negative-polarity devices (“N” suffix) are off when the On/Off Control is open

(or pulled high), and on when the On/Off Control is pulled low with respect to

Dynamic control of the remote on/off function is facilitated with a mechanical

relay or an open-collector/open-drain drive circuit (optically isolated if appropri-

ate). The drive circuit should be able to sink appropriate current (see Performance

Specs) when activated and withstand appropriate voltage when deactivated.

Applying an external voltage to the On/Off Control when no input power is

applied to the converter can cause permanent damage to the converter.

Trimming Output Voltage

UWE converters have a trim capability that allows users to adjust the output

voltages. Adjustments to the output voltages can be accomplished via a trim pot

(Figure 6) or a single fixed resistor as shown in Figures 7 and 8. A single fixed

resistor can increase or decrease the output voltage depending on its connec-

tion. The resistor should be located close to the converter and have a TCR less

than 100ppm/°C to minimize sensitivity to changes in temperature. If the trim

function is not used, leave the trim pin floating.

A single resistor connected from the Trim to the +Output, or +Sense where

applicable, will increase the output voltage in this configuration. A resistor con-

nected from the Trim to the –Output, or –Sense where applicable, will decrease

the output voltage in this configuration.

Trim adjustments greater than the specified range can have an adverse

affect on the converter's performance and are not recommended. Excessive

ment of the output voltage, can cause the overvoltage protection circuitry to

activate (see Performance Specifications for overvoltage limits). Power derating

is based on maximum output current and voltage at the converter’s output

pins. Use of trim and sense functions can cause output voltages to increase,

thereby increasing output power beyond the converter's specified rating or

cause output voltages to climb into the output overvoltage region. Therefore:

ON/OFF CONTROL

CONTROL

+ Vcc

-INPUT

Figure 4. Driving the Positive Polarity On/Off Control Pin

–INPUT

ON/OFF

CONTROL

+ Vcc

Figure 5. Driving the Negative Polarity On/Off Control Pin

LOAD

R2

+OUTPUT

–INPUT

+INPUT

ON/OFF

CONTROL

TRIM

+SENSE

–OUTPUT

–SENSE

Figure 8. Trim Connections To Decrease Output Voltages

20k

:

5-20

TURNS

LOAD

+OUTPUT

–INPUT

+INPUT

ON/OFF

CONTROL

TRIM

+SENSE

–OUTPUT

–SENSE

Figure 6. Trim Connections Using A Trimpot

LOAD

R1

+OUTPUT

–INPUT

+INPUT

ON/OFF

CONTROL

TRIM

+SENSE

–OUTPUT

–SENSE

Figure 7. Trim Connections To Increase Output Voltages Using a Fixed Resistor

MDC_UWE Series.A17 Page 11 of 20