GE Industrial Solutions NH020-Series - Manual (Page 8)

Lineage Power 8
Data Sheet
October 14, 2009
5 Vdc Input; 1.5 Vdc to 3.3 Vdc Output; 20 W
NH020-Series Power SIPs:
Test Configurations
Note: Measure input reflected ripple current with a simulated source
inductance (L TEST ) of 500nH. Capacitor CS offsets possible
battery impedance. Measure current as shown above.
Figure 14. Input Reflected Ripple Current Test Setup.
Note: Scope measurements should be made using a BNC socket,
with a 47 µF tantalum capacitor .Position the load between 51
mm and 76 mm (2 in and 3 in) from the module
Figure 15. Peak-to-Peak Output Ripple Measurement
Test Setup.
Note: All voltage measurements to be taken at the module termi-
nals, as shown above. If sockets are used then Kelvin con-
nections are required at the module terminals to avoid
measurement
errors due to socket contact resistance.
Figure 16. Output Voltage and Efficiency Test Setup.
Design Considerations
Input Source Impedance
The power SIP should be connected to a low ac- impedance
input source. Highly inductive source impedances can affect
the stability of the SIP. Adding external capacitance close to
the input pins of the SIP can reduce the ac impedance and
ensure system stability. The minimum recommended input
capacitance (C1) is a 100 µF electrolytic capacitor (see Fig-
ures 17 and 19).
Figure 17. Setup with External Capacitor to Reduce
Input Ripple Voltage .
To reduce the amount of ripple current fed back to the input
supply (input reflected-ripple current), an external input filter
can be added. Up to 10 µF of ceramic capacitance (C2) may
be externally connected to the input of the SIP, provided the
source inductance (LSOURCE) is less than 1 µH (see Figure
17).
To further reduce the input reflected-ripple current, a
filter inductor (LFILTER) can be connected between the sup-
ply and the external input capacitors (see Figure 18).
As mentioned above, a 100 µF electrolytic capacitor (C1)
should be added across the input of the SIP to ensure stabil-
ity of the unit. The electrolytic capacitor should be selected
for ESR and RMS current ratings to ensure safe operation in
the case of a fault condition. Refer to Figure 19 for the
appropriate electrolytic capacitor ratings.
When using a tantalum input capacitor, take care not to
exceed device power rating because of the capacitor’s fail-
ure mechanism (for example, a short circuit). The
filter inductor should be rated to handle the maximum power
SIP input current of 6.1 Adc.
If the amount of input reflected-ripple current is unaccept-
able with an external L-C filter, more capacitance may be
added across the input supply to form a C-L-C filter. For best
results, the filter components should be mounted close to
the power SIP.
T O O SC ILLO SC O PE
500 nH
C S 220 µ F
ESR < 0.1 •
@ 20 °C , 100 k H z
V I ( + )
V I ( –)
BAT T ER Y
L
η
V
O(+)
V
O(-)
–
[ ] I
O
×
V
I(+)
V
I(-)
–
[ ] I
I
Ч
------------------------------------------------ ⎝ ⎠
⎛ ⎞
100
Ч
=