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

Ω ·

0.8 V

– 2.49 k

Ω

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

Ω

0.850

158 k

Ω

0.875

104 k

Ω

0.900

77.5 k

Ω

0.925

61.5 k

Ω

0.950

50.8 k

Ω

0.975

43.2 k

Ω

1.000

37.5 k

Ω

1.025

33.1 k

Ω

1.050

29.5 k

Ω

1.075

26.6 k

Ω

1.100

24.2 k

Ω

1.125

22.1 k

Ω

1.150

20.4 k

Ω

1.175

18.8 k

Ω

1.200

17.5 k

Ω

1.225

16.3 k

Ω

1.250

15.3 k

Ω

1.275

14.4 k

Ω

1.300

13.5 k

Ω

1.325

12.7 k

Ω

1.350

12.1 k

Ω

1.375

11.4 k

Ω

1.400

10.8 k

Ω

1.425

10.3 k

Ω

1.450

9.82 k

Ω

1.475

9.36 k

Ω

1.50

8.94 k

Ω

1.55

8.18 k

Ω

1.60

7.51 k

Ω

1.65

6.92 k

Ω

1.70

6.4 k

Ω

1.75

5.93 k

Ω

1.80

5.51 k

Ω

1.85

5.13 k

Ω

1.90

4.78 k

Ω

1.95

4.47 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 R

set

for Standard Output Voltages

PTH03030W & PTH05030W

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

Va Req’dRset

Va Req’dRset

2.00

4.18 k

Ω

2.05

3.91 k

Ω

2.10

3.66 k

Ω

2.15

3.44 k

Ω

2.20

3.22 k

Ω

2.25

3.03 k

Ω

2.30

2.84 k

Ω

2.35

2.67 k

Ω

2.40

2.51 k

Ω

2.45

2.36 k

Ω

2.50

2.22 k

Ω

2.55

2.08 k

Ω

2.60

1.95 k

Ω

2.65

1.83 k

Ω

2.70

1.72 k

Ω

2.75

1.61 k

Ω

2.80

1.51 k

Ω

2.85

1.41 k

Ω

2.90

1.32 k

Ω

2.95

1.23 k

Ω

3.00

1.15 k

Ω

3.05

1.07 k

Ω

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

C

OUT

330 µF

(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

GND