Application Notes
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Adjusting the Output Voltage of the PTH03030W &
PTH05030W Wide-Output Adjust Power Modules
The Vo Adjust control (pin 4) sets the output voltage of the
PTH03030W and PTH05030W products to a value higher
than 0.8 V. The adjustment range of the PT03030W
(3.3-V input) is from 0.8 V to 2.5 V 1, and the PTH05030W
(5-V input) from 0.8 V to 3.6 V. For an output voltage
other than 0.8 V a single external resistor, Rset, must be
connected directly between the Vo Adjust and GND pins 2.
Table 2-1 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 2-2.
Figure 2-1 shows the placement of the required resistor.
Rset
= 10 k
0.8 V
– 2.49 k
Vout – 0.8 V
Figure 2-1; V
o
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 5 and 10 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.
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 1
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 2-1; Preferred Values of R
set
for Standard Output Voltages
PTH03030W & PTH05030W
Table 2-2; 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
C
OUT
330 F
(Optional)
GND
V
OUT
V
o Sense
R
SET
1 %, 0.1 W
PTH05030W
1, 3, 7
13
6
8, 9
12
11
5
GND
Adjust
V
O
Sense
10
GND