Application Notes

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Adjusting the Output Voltage of the PTH03050W &

PTH05050W Wide-Output Adjust Power Modules

The Vo Adjust control (pin 5) sets the output voltage to a

value higher than 0.8 V. The adjustment range of the

PT03050W (3.3-V input) is from 0.8 V to 2.5 V 1, and

the PTH05050W (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 2-1 gives

the preferred value of the external resistor for a number

of standard voltages, along with the actual output volt-

age 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

Ω ·

0.8 V

– 2.49 k

Ω

Vout – 0.8 V

Figure 2-1; 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. A 0.05-W resistor may be used. 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 1 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

0.825318 k

Ω

0.850

158 k

Ω

0.875104 k

Ω

0.900

77.5 k

Ω

0.92561.5

k

Ω

0.950

50.8 k

Ω

0.97543.2 k

Ω

1.000

37.5 k

Ω

1.02533.1 k

Ω

1.050

29.5 k

Ω

1.07526.6 k

Ω

1.100

24.2 k

Ω

1.12522.1 k

Ω

1.150

20.4 k

Ω

1.17518.8 k

Ω

1.200

17.5 k

Ω

1.22516.3 k

Ω

1.250

15.3 k

Ω

1.27514.4 k

Ω

1.300

13.5 k

Ω

1.32512.7 k

Ω

1.350

12.1 k

Ω

1.37511.4 k

Ω

1.400

10.8 k

Ω

1.42510.3 k

Ω

1.450

9.82 k

Ω

1.4759.36 k

Ω

1.50

8.94 k

Ω

1.55

8.18 k

Ω

1.60

7.51 k

Ω

1.656.92 k

Ω

1.70

6.4 k

Ω

1.755

.93 k

Ω

1.80

5.51 k

Ω

1.855

.13 k

Ω

1.90

4.78 k

Ω

1.954.47 k

Ω

Vout (Standard)

Rset (Pref’d Value)

Vout (Actual)

3.3 V 1

698

Ω

3.309V

2.5 V

2.21 k

Ω

2.502 V

2 V

4.12 k

Ω

2.010 V

1.8 V

5.49 k

Ω

1.803 V

1.5 V

8.87 k

Ω

1.504 V

1.2 V

17.4 k

Ω

1.202 V

1 V

36.5 k

Ω

1.005 V

0.8 V

Open

0.8 V

Table 2-1; Preferred Values of Rset for Standard Output Voltages

PTH03050W & PTH05050W

Table 2-2; Output Voltage Set-Point Resistor Values

Va Req’dRset

Va Req’dRset

2.00

4.18 k

Ω

2.053.91 k

Ω

2.10

3.66 k

Ω

2.153.44 k

Ω

2.20

3.22 k

Ω

2.253.03 k

Ω

2.30

2.84 k

Ω

2.352.67 k

Ω

2.40

2.51 k

Ω

2.452.36 k

Ω

2.50

2.22 k

Ω

2.55

2.08 k

Ω

2.60

1.95 k

Ω

2.651.83 k

Ω

2.70

1.72 k

Ω

2.751.61 k

Ω

2.80

1.51 k

Ω

2.851.41 k

Ω

2.90

1.32 k

Ω

2.951.23 k

Ω

3.00

1.15 k

Ω

3.051.07 k

Ω

3.10

988

Ω

3.15914

Ω

3.20

843

Ω

3.25775

Ω

3.30

710

Ω

3.35647

Ω

3.40

587

Ω

3.455

29

Ω

3.50

473

Ω

3.55

419

Ω

3.60

367

Ω

V

IN

C

IN

100 µF

(Required)

C

OUT

100 µF

(Optional)

GND

V

OUT

R

SET

1 %

0.1 W

PTH03050W

15

6

3

4

2

Track

V

IN

V

O

GND

Inhibit