PTV12020

10, 11

7

3, 4

GND

GN D

1, 2

GND

VO Sense

VO

VO Adj

VO Sense

VO

CO

330 mF

(Optional)

8

RSET

1%, 0.05W

PTV12020W/L

SLTS231C – NOVEMBER 2004 – REVISED FEBRUARY 2007

www.ti.com

APPLICATION INFORMATION

ADJUSTING THE OUTPUT VOLTAGE

The VO Adjust control (pin 8) sets the output voltage of the PTV12020 product. The adjustment range is from

1.2 V to 5.5 V for the W-suffix modules and 0.8 V to 1.8 V 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

(pin 1 or 2). Table 1 gives the standard 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 Equation 1 or simply selected from the range of values given in

Table 3.Figure 11 shows the placement of the required resistor.

Table 1. Standard Values of RSET for Common Output Voltages

PTV12020W

PTV12020L

VO (V)

RSET (kΩ)

VO (V)

RSET (kΩ)

VO (V)

(Required)

(Standard Value)

(Actual)

(Standard Value)

(Actual)

5

0.280

5.009

N/A

N/A

3.3

2.0

3.294

N/A

N/A

2.5

4.32

2.503

N/A

N/A

2

8.06

2.010

N/A

N/A

1.8

11.5

1.801

0.130

1.800

1.5

24.3

1.506

3.57

1.499

1.2

Open

1.200

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

0.800

(1)

A 0.05-W rated 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 pin 8 and pins 1

or 2, using dedicated PCB traces.

(2)

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

stability of the regulator.

Figure 11. VOAdjust Resistor Placement

8

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