PTV08040WAD datasheet(10/23 Pages) TI

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ADJUSTING THE OUTPUT VOLTAGE OF THE PTV08040W WIDE-OUTPUT ADJUST POWER

)

-0.8

0.8

-7.135kW

(

=30.1

SET

(1)

PTV08040W

0.05W

SET

12 18 19 4 5 11

C 2

C 1

GND

VOAdj

+Sense

-Sense

GND

PTV08040W

SLTS257A – SEPTEMBER 2005 – REVISED JANUARY 2007

MODULE

The VO Adjust control (pin 8) sets the output voltage of the PTV08040W product. The adjustment range is 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. Table 2 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 Equation 1, or simply

selected from the range of values given in Table 3. Figure 9 shows the placement of the required resistor.

Table 2. Standard Values of RSET for Common Output

Voltages

PTV08040W

VO (Required)

RSET

VO (Actual)

3.3 V

2.49 k

Ω

3.303 V

2.5 V

6.98 k

Ω

2.5 V

2.0 V

13.0 k

Ω

1.997 V

1.8 V

16.9 k

Ω

1.796 V

1.5 V

27.4 k

Ω

1.498 V

1.2 V

53.6 k

Ω

1.202 V

1.0 V

113 k

Ω

1 V

0.8 V

Open

0.8 V

Figure 9. VO Adjust Resistor Placement

• A 0.05-W rated resistor may be used. The tolerance should be 1%, and the temperature stability, 100

ppm/

°C (or better). Place the resistor as close to the regulator as possible. Connect the resistor directly

between pin 8 and nearest GND pin (pin 11) using dedicated PCB traces.

• Never connect capacitors from V

O Adjust to either GND or VO. Any capacitance added to the VO Adjust pin

affects the stability of the regulator.

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