APPLICATION INFORMATION

ADJUSTING THE OUTPUT VOLTAGE

V

I

GND

V

O

V Sense

O

R

1%

SET

PTH12060

1

10

4

5

6

2

3

9

7

8

C

330 F

(Optional)

O

m

C

560 F

(Required)

I

m

PTH12060W/L

SLTS217H – MAY 2003 – REVISED DECEMBER 2008 .................................................................................................................................................... www.ti.com

The VOAdjust control (pin 4) sets the output voltage of the PTH12060W/L. The adjustment range is from 1.2V to

5.5V for the W-suffix modules, and 0.8V to 1.8V for L-suffix modules. The adjustment method requires the

addition of a single external resistor, RSET, that must be connected directly between the VOAdjust and GND

pins(1). Table 1 gives the standard value of the external resistor for a number of standard voltages, along with the

actual output voltage that the resistance value provides. For other output voltages the value of the required

resistor can either be calculated using Equation 1, or simply selected from the range of values given in Table 3.

Figure 9 shows the placement of the required resistor.

Table 1. Standard Values of RSET for Standard Output Voltages

PTH12060W

PTH12060L

VO(V)

VO(V)

VO(V)

RSET (kΩ)

RSET(kΩ)

(Required)

(Actual)

(Actual)

5

0.280

5.009

N/A

N/A

3.3

2

3.294

N/A

N/A

2.5

4.32

2.503

N/A

N/A

2

8.06

2.01

N/A

N/A

1.8

11.5

1.801

0.130

1.8

1.5

24.3

1.506

3.57

1.499

1.2

Open

1.2

12.1

1.201

1.1

N/A

N/A

18.7

1.101

1.0

N/A

N/A

32.4

0.999

0.9

N/A

N/A

71.5

0.901

0.8

N/A

N/A

Open

0.8

(1)

RSET: Use a 0.05-W rated resistor with a 1% tolerance and temperature stability of 100 ppm/°C or better. Place the

resistor directly between pins 4 and 7, as close to the regulator as possible, using dedicated PCB traces.

(2)

Never connect capacitors from VO Adjust to either GND or VO. Any capacitance added to the VO Adjust pin affects the

stability of the regulator.

Figure 9. VO Adjust Resistor Placement

8

Submit Documentation Feedback

Copyright © 2003–2008, Texas Instruments Incorporated

Product Folder Link(s): PTH12060W/L