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Application Notes
For technical support and further information, visit http://power.ti.com
Adjusting the Output Voltage of the PTH03020W &
PTH05020W Wide-Output Adjust Power Modules
The Vo Adjust control (pin 4) sets the output voltage of
the PTH03020W and PTH05020W products. The
adjustment range of the PT03020W (3.3-V input) is
from 0.8 V to 2.5 V 1, and the PTH05020W (5-V input)
from 0.8 V to 3.6 V. The adjustment method requires the
addition of a single external resistor, Rset, that must be
connected directly between the Vo Adjust and GND pins 2.
Table 1-1 gives the preferred value of the external resistor
for a number of standard voltages, along with the actual
output voltage that this resistance value provides.
For other output voltages the value of the required resistor
can either be calculated using the following formula, or
simply selected from the range of values given in Table 1-2.
Figure 1-1 shows the placement of the required resistor.
Rset
= 10 k
0.8 V
– 2.49 k
Vout – 0.8 V
Figure 1-1; Vo Adjust Resistor Placement
Notes:
1. Modules that operate from a 3.3-V input bus should
not be adjusted higher than 2.5 V.
2. Use a 0.1 W resistor. The tolerance should be 1 %, with
temperature stability of 100 ppm/°C (or better). Place
the resistor as close to the regulator as possible. Connect
the resistor directly between pins 4 and 7 using dedicated
PCB traces.
3. Never connect capacitors from Vo Adjust to either GND or
Vout. Any capacitance added to the Vo Adjust pin will affect
the stability of the regulator.
PTH05020W
14
5
6
C
OUT
330F
+
GND
V
OUT
V
O Sense [Note 3]
V
O Adj
GND
V
O Sense
V
OUT
R
SET
0.1 W, 1 %
10
9
8
7
GND
0.800
Open
0.825
318 k
0.850
158 k
0.875
104 k
0.900
77.5 k
0.925
61.5 k
0.950
50.8 k
0.975
43.2 k
1.000
37.5 k
1.025
33.1 k
1.050
29.5 k
1.075
26.6 k
1.100
24.2 k
1.125
22.1 k
1.150
20.4 k
1.175
18.8 k
1.200
17.5 k
1.225
16.3 k
1.250
15.3 k
1.275
14.4 k
1.300
13.5 k
1.325
12.7 k
1.350
12.1 k
1.375
11.4 k
1.400
10.8 k
1.425
10.3 k
1.450
9.82 k
1.475
9.36 k
1.50
8.94 k
1.55
8.18 k
1.60
7.51 k
1.65
6.92 k
1.70
6.4 k
1.75
5.93 k
1.80
5.51 k
1.85
5.13 k
1.90
4.78 k
1.95
4.47 k
Vout (Standard)
Rset (Pref’d Value)
Vout (Actual)
3.3 V 2
698
3.309V
2.5 V
2.21 k
2.502 V
2 V
4.12 k
2.010 V
1.8 V
5.49 k
1.803 V
1.5 V
8.87 k
1.504 V
1.2 V
17.4 k
1.202 V
1 V
36.5 k
1.005 V
0.8 V
Open
0.8 V
Table 1-1; Preferred Values of Rset for Standard Output Voltages
PTH03020W & PTH05020W
Table 1-2; Output Voltage Set-Point Resistor Values
Va Req’dRset
2.00
4.18 k
2.05
3.91 k
2.10
3.66 k
2.15
3.44 k
2.20
3.22 k
2.25
3.03 k
2.30
2.84 k
2.35
2.67 k
2.40
2.51 k
2.45
2.36 k
2.50
2.22 k
2.55
2.08 k
2.60
1.95 k
2.65
1.83 k
2.70
1.72 k
2.75
1.61 k
2.80
1.51 k
2.85
1.41 k
2.90
1.32 k
2.95
1.23 k
3.00
1.15 k
3.05
1.07 k
3.10
988
3.15
914
3.20
843
3.25
775
3.30
710
3.35
647
3.40
587
3.45
529
3.50
473
3.55
419
3.60
367