DS_NC12S60A_01102008
10
Voltage Margin Adjusting
Output voltage margin adjusting can be implemented in
the NC60A modules by connecting a resistor, R
margin-up,
from the Trim pin to the ground pin for adjusting voltage
a little bit higher. Also, the output voltage can be
adjusted lower by connecting a resistor, R
margin-down
, from
the Trim pin to the output pin. Figure 34 shows the
circuit configuration for output voltage margin adjusting.
Figure 34: Circuit configuration for output voltage margining
Output Capacitance
An external output capacitor is required for stable
operation.
Reflected Ripple Current and Output Ripple
and Noise Measurement
The measurement set-up outlined in Test Configuration
Figure 35
have been used for both input
reflected/terminal ripple current and output voltage
ripple and noise measurements on NC series
converters.
Cs Cin
Ltest
1 2
Vin+
DC-DC Converter
Cout
Ceramic
100nF
Tantalum
10uF
LOAD
Input reflected current measurement point
Output voltage ripple noise measurement point
Cs=270uF*1 Ltest=1.4uH Cin=270uF*3 Cout=680uF*4
Figure 35:Input Reflected Ripple/Capacitor Ripple Current
and Output Voltage Ripple and Noise Measurement Set-Up for
NC60A
Cout
Rmargin-down
0
Vt
-SENSE
Rmargin-up
+SENSE
GROUND
Rs
Vout
TRIM
THERMAL CONSIDERATION
The electrical operating conditions of the NC, namely:
●
Input voltage, Vin
● Output voltage, V
o
●
Output current, Io
Determine how much power is dissipated within the
converter. The following parameters further influence the
thermal stresses experienced by the converter:
●
Ambient temperature
● Air velocity
●
Thermal efficiency of the end system application
● Parts mounted on system PCB that may block airflow
●
Real airflow characteristics at the converter location
In order to simplify the thermal design, a number of thermal
de-rating plots are provided. These de-rating graphs show
the load current of the NC versus the ambient air
temperature and air flow. However, since the thermal
performance is heavily dependent upon the final system
application, the user needs to ensure the thermal reference
point temperatures are kept within the recommended
temperature rating. It is recommended that the thermal
reference point temperatures are measured using a
thermocouple or an IR camera. In order to comply with
stringent Delta de-rating criteria, the ambient temperature
should never exceed 85℃. Please contact Delta for further
support..
The maximum acceptable temperature measured at the
thermal reference point is 127℃. This is shown in Figure
36.
MODULE
(11 Seiten)
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