Technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232

MTU1 Series

Isolated 1W Single Output SM DC/DC Converters

2011-02-01

KDC_MTU.A03 Page 3 of 6

www.murata-ps.com

APPLICATION NOTES

Minimum load

The minimum load to meet datasheet specification is 10% of the full rated load across the specified input voltage range. Lower than 10% minimum loading will result in

an increase in output voltage, which may rise to typically double the specified output voltage if the output load falls to less than 5%.

Capacitive loading and start up

Typical start up times for this series, with a typical input voltage rise time of 2.2μs and output capacitance of 10μF, are shown in the table below. The product

series will start into a capacitance of 47μF with an increased start time, however, the maximum recommended output capacitance is 10μF.

Ripple & Noise Characterisation Method

Ripple and noise measurements are performed with the following test configuration.

C1

1μF X7R multilayer ceramic capacitor, voltage rating to be a minimum of 3 times the output voltage of the DC/DC converter

C2

10μF tantalum capacitor, voltage rating to be a minimum of 1.5 times the output voltage of the DC/DC converter with an ESR of less

than 100mΩ at 100 kHz

C3

100nF multilayer ceramic capacitor, general purpose

R1

450Ω resistor, carbon film, ±1% tolerance

R2

50Ω BNC termination

T1

3T of the coax cable through a ferrite toroid

RLOAD

Resistive load to the maximum power rating of the DC/DC converter. Connections should be made via twisted wires

Measured values are multiplied by 10 to obtain the specified values.

Differential Mode Noise Test Schematic

OSCILLOSCOPE

Y INPUT

SUPPLY

C1 C2 C3

R1

T1

R2

Input

Output

DC/DC Converter

R LOAD

+

+

-

-

Typical Start-Up Wave Form

Start-up time

ms

MTU1S0505MC

0.9

MTU1S0509MC

2.7

MTU1S0512MC

4.3

MTU1S0515MC

7.5

MTU1S1205MC

0.9

MTU1S1209MC

1.9

MTU1S1212MC

3.3

MTU1S1215MC

4.7