Datasheet

Application Notes
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Adjusting the Output Voltage of the PTH03020W &
PTH05020W Wide-Output Adjust Power Modules
The V
o
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, R
set
, that must be
connected directly between the V
o
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.
R
set
= 10 kΩ ·
0.8 V
– 2.49 kΩ
V
out
– 0.8 V
Figure 1-1; 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 4 and 7 using dedicated
PCB traces.
3. Never connect capacitors from V
o
Adjust to either GND or
V
out
. Any capacitance added to the V
o
Adjust pin will affect
the stability of the regulator.
PTH05020W
14
5
6
C
OUT
330µF
+
GND
V
OUT
V
O
Sense [Note 3]
V
O
AdjGND
V
O
Sense
V
OUT
R
SET
0.1 W, 1 %
10 9 8
7
GND
0.800 Open
0.825 318 kΩ
0.850 158 kΩ
0.875 104 kΩ
0.900 77.5 kΩ
0.925 61.5 kΩ
0.950 50.8 kΩ
0.975 43.2 kΩ
1.000 37.5 kΩ
1.025 33.1 kΩ
1.050 29.5 kΩ
1.075 26.6 kΩ
1.100 24.2 kΩ
1.125 22.1 kΩ
1.150 20.4 kΩ
1.175 18.8 kΩ
1.200 17.5 kΩ
1.225 16.3 kΩ
1.250 15.3 kΩ
1.275 14.4 kΩ
1.300 13.5 kΩ
1.325 12.7 kΩ
1.350 12.1 kΩ
1.375 11.4 kΩ
1.400 10.8 kΩ
1.425 10.3 kΩ
1.450 9.82 kΩ
1.475 9.36 kΩ
1.50 8.94 kΩ
1.55 8.18 kΩ
1.60 7.51 kΩ
1.65 6.92 kΩ
1.70 6.4 kΩ
1.75 5.93 kΩ
1.80 5.51 kΩ
1.85 5.13 kΩ
1.90 4.78 kΩ
1.95 4.47 kΩ
V
out
(Standard) R
set
(Pref’d Value) V
out
(Actual)
3.3 V
2
698 Ω 3.309V
2.5 V 2.21 kΩ 2.502 V
2 V 4.12 kΩ 2.010 V
1.8 V 5.49 kΩ 1.803 V
1.5 V 8.87 kΩ 1.504 V
1.2 V 17.4 kΩ 1.202 V
1 V 36.5 kΩ 1.005 V
0.8 V Open 0.8 V
Table 1-1; Preferred Values of R
set
for Standard Output Voltages
PTH03020W & PTH05020W
Table 1-2; Output Voltage Set-Point Resistor Values
V
a
Req’dR
set
V
a
Req’dR
set
2.00 4.18 kΩ
2.05 3.91 kΩ
2.10 3.66 kΩ
2.15 3.44 kΩ
2.20 3.22 kΩ
2.25 3.03 kΩ
2.30 2.84 kΩ
2.35 2.67 kΩ
2.40 2.51 kΩ
2.45 2.36 kΩ
2.50 2.22 kΩ
2.55 2.08 kΩ
2.60 1.95 kΩ
2.65 1.83 kΩ
2.70 1.72 kΩ
2.75 1.61 kΩ
2.80 1.51 kΩ
2.85 1.41 kΩ
2.90 1.32 kΩ
2.95 1.23 kΩ
3.00 1.15 kΩ
3.05 1.07 kΩ
3.10 988 Ω
3.15 914 Ω
3.20 843 Ω
3.25 775 Ω
3.30 710 Ω
3.35 647 Ω
3.40 587 Ω
3.45 529 Ω
3.50 473 Ω
3.55 419 Ω
3.60 367 Ω