TEST CONFIGURATIONS
TO OSCILLOSCOPE
DESIGN CONSIDERATIONS
Input Source Impedance
V
I
(+)
L
2
100uF
Tantalum
BATTERY
To maintain low-noise and ripple at the input voltage, it is
critical to use low ESR capacitors at the input to the
module. The input capacitance should be able to handle
an AC ripple current of at least:
Irms
=
Iout
Vout
⎛
Vout
⎞
⎜
1
−
⎟
Vin
⎝
Vin
⎠
Arms
V
I
(-)
Note:
Input reflected-ripple current is measured with a
simulated source inductance. Current is measured at
the input of the module.
Figure 19:
Input reflected-ripple test setup
COPPER STRIP
Vo
1uF
10uF
SCOPE
tantalum ceramic
The power module should be connected to a low
ac-impedance input source. Highly inductive source
impedances can affect the stability of the module. An
input capacitance must be placed close to the modules
input pins to filter ripple current and ensure module
stability in the presence of inductive traces that supply
the input voltage to the module.
Safety Considerations
Resistive
Load
GND
For safety-agency approval the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standards.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the
input must meet SELV requirements. The power module
has extra-low voltage (ELV) outputs when all inputs are
ELV.
The input to these units is to be provided with a
maximum (TBD) A of glass type fast-acting fuse in the
ungrounded lead.
Note:
Use a 10µF tantalum and 1µF capacitor. Scope
measurement should be made using a BNC connector.
Figure 20:
Peak-peak output noise and startup transient
measurement test setup
CONTACT AND
DISTRIBUTION LOSSES
VI
Vo
Io
LOAD
I
SUPPLY
GND
CONTACT RESISTANCE
Figure 21:
Output voltage and efficiency measurement test
setup
Note:
All measurements are taken at the module terminals.
When the module is not soldered (via socket), place
Kelvin connections at module terminals to avoid
measurement errors due to contact resistance.
η
=
(
Vo
×
Io
)
×
100 %
Vi
×
Ii
DS_DNT12SMD03_06252007
6
DELTA [ DELTA ELECTRONICS, INC. ]
