TEST CONFIGURATIONS
TO OSCILLOSCOPE
DESIGN CONSIDERATIONS
Input Source Impedance
V
I
(+)
L
2
47uF
Tantalum
BATTERY
V
I
(-)
Note: Input reflected-ripple current is measured with a
simulated source inductance. Current is
measured at the input of the module.
Figure 23:
Input reflected-ripple current test setup
To maintain low-noise and ripple at the input voltage, it is
critical to use low ESR capacitors at the input to the
module. Figure 26 shows the input ripple voltage
(mVp-p) for various output models using 2x47 uF low
ESR tantalum capacitors (SANYO P/N:16TPB470M,
47uF/16V or equivalent) or 2x22 uF very low ESR
ceramic capacitors (TDK P/N:C3225X7S1C226MT,
22uF/16V or equivalent).
The input capacitance should be able to handle an AC
ripple current of at least:
Irms
=
Iout
Vout
⎛
Vout
⎞
⎜
1
−
⎟
Vin
⎝
Vin
⎠
Arms
COPPER STRIP
Vo
1uF
10uF
tantalum ceramic
SCOPE
Resistive
Load
400
Input Ripple Voltage (mVp-p)
350
300
250
200
150
100
50
0
GND
Note: Use a 10µF tantalum and 1µF capacitor. Scope
measurement should be made using a BNC
connector.
Figure 24:
Peak-peak output noise and startup transient
measurement test setup
CONTACT AND
DISTRIBUTION LOSSES
Tantalum
Ceramic
0
1
2
3
Output Voltage (Vdc)
4
5
6
V
I
I
I
SUPPLY
Vo
Io
LOAD
GND
Figure 26:
Input ripple voltage for various output models,
Io = 8A (Cin = 2x47uF tantalum capacitors or
2x22uF ceramic capacitors at the input)
CONTACT RESISTANCE
Figure 25:
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.
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.
η
=
(
Vo
×
Io
)
×
100 %
Vi
×
Ii
7
DS_IPM12S0A008_12182006
DELTA [ DELTA ELECTRONICS, INC. ]
