Test Configurations; Design Considerations - Delta Electronics Delphi Series DNS Datasheet

TEST CONFIGURATIONS

TO OSCILLOSCOPE
L
BATTERY
Note: Input reflected-ripple current is measured with a
simulated source inductance. Current is measured at
the input of the module.
Figure 29: Input reflected-ripple test setup
COPPER STRIP
Vo
10uF 1uF
tantalum ceramic
GND
Note: Use a 10μF tantalum and 1μF capacitor. Scope
measurement should be made using a BNC connector.
Figure 30: Peak-peak output noise and startup transient
measurement test setup.
V Vo
I
I
I
SUPPLY
GND
CONTACT RESISTANCE
Figure 31: 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.
×
Vo Io
η
=
(
×
Vi Ii
DS_DNS04SIP06A_07172008
V (+)
I
2
100uF
Tantalum
V (-)
I
Resistive
SCOPE
Load
CONTACT AND
DISTRIBUTION LOSSES
Io
LOAD
×
) 100 %

DESIGN CONSIDERATIONS

Input Source Impedance
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 32 shows the input ripple voltage (mVp-p)
for various output models using 2x100 µF low ESR
capacitor (KEMET p/n: T491D107M016AS,
tantalum
AVX p/n: TAJD107M106R, or equivalent) in parallel with
47 µF ceramic capacitor (TDK p/n:C5750X7R1C476M or
equivalent). Figure 33 shows much lower input voltage
ripple when input capacitance is increased to 400 µF (4 x
100 µF) capacitors in parallel with 94 µF (2 x 47
tantalum
µF) ceramic capacitor.
The input capacitance should be able to handle an AC
ripple current of at least:
⎛
Vout Vout
= −
⎜ 1
Irms Iout
⎝
Vin Vin
200
150
100
50
0
0 1
Output Voltage (Vdc)
Figure 32: Input voltage ripple for various output models, Io =
6A (CIN = 2 100µF tantalum // 47µF ceramic)
×
80
60
40
20
0
0 1
Output Voltage (Vdc)
Figure 33: Input voltage ripple for various output models, Io =
6A (CIN = 4 100µF tantalum // 2
×
⎞
⎟
Arms
⎠
3.3Vin
5.0Vin
2 3 4
3.3Vin
5.0Vin
2 3 4
47µF ceramic)
×
8