Datasheet

DS_DNT04SMD05_07182012
9
FEATURE DESCRIPTIONS (CON.)
Table 1 provides Rtrim values required for some common
output voltages, while Table 2 provides value of external
voltage source, Vtrim, for the same common output
voltages. By using a 1% tolerance trim resistor, set point
tolerance of ±2% can be achieved as specified in the
electrical specification.
Table 1
VO (V)
Rtrim (KΩ)
0.7525
Open
1.2
41.973
1.5
23.077
1.8
15.004
2.5
6.947
3.3
3.160
3.63
2.212
Table 2
VO (V)
Vtrim (V)
0.7525
Open
1.2
0.6240
1.5
0.5731
1.8
0.5221
2.5
0.4033
3.3
0.2674
3.63
0.2114
Vo
TRIM
GND
RLoad
Vtrim
+
_
Figure 29: Circuit Configuration for programming output voltage
using external voltage source
The amount of power delivered by the module is the
voltage at the output terminals multiplied by the output
current. When using the trim feature, the output voltage of
the module can be increased, which at the same output
current would increase the power output of the module.
Care should be taken to ensure that the maximum output
power of the module must not exceed the maximum rated
power (Vo.set x Io.max ≤ P max).
Voltage Margining
Output voltage margining can be implemented in the DNT
modules by connecting a resistor, R margin-up, from the Trim
pin to the ground pin for margining-up the output voltage
and by connecting a resistor, Rmargin-down, from the Trim pin
to the output pin for margining-down. Figure 32 shows the
circuit configuration for output voltage margining. If unused,
leave the trim pin unconnected. A calculation tool is
available from the evaluation procedure which computes
the values of R margin-up and Rmargin-down for a specific output
voltage and margin percentage.
Vo
On/Off
Vin
GND
Trim
Q2
Q1
Rmargin-up
Rmargin-down
Rtrim
Figure 30: Circuit configuration for output voltage margining