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APPLICATION INFORMATION

Adjusting the Output Voltage of the PTN78060 Wide-Output Adjust Power Modules

General

R

= 54.9 k

SET

1.25 V

V

- V

O

min

- R

P

(1)

Input Voltage Considerations

PTN78060W, PTN78060H

SLTS229A – NOVEMBER 2004 – REVISED APRIL 2005

The adjustment range is from 2.5 V to 12.6 V for PTN78060W. The adjustment range is from 11.85 V to 22 V for

PTN78060H. If pin 4 is left open, the output voltage defaults to the lowest value.

Table 2 gives the standard resistor value for a number of common voltages, and with the actual output voltage

of values given in Table 3 and Table 4. Figure 27 shows the placement of the required resistor.

PRODUCT

PTN780x0W

2.5 V

6.49 k

Ω

PTN780x0H

11.824 V

6.65 k

Ω

The PTN78060 is a step-down switching regulator. In order that the output remains in regulation, the input

voltage must exceed the output by a minimum differential voltage.

Another consideration is the pulse width modulation (PWM) range of the regulator's internal control circuit. For

stable operation, its operating duty cycle should not be lower than some minimum percentage. This defines the

maximum advisable ratio between the regulator input and output voltage magnitudes.

For satisfactory performance, the operating input voltage range of the PTN78060x must adhere to the following

requirements.

is higher.

3. The maximum input voltage for PTN78060W is (10

× V

is higher.

As an example, Table 2 gives the operating input voltage range for the common output bus voltages. In addition,

the Electrical Characteristics table defines the available output voltage adjust range for various input voltages.

Operating

PRODUCT

(Required)

(Standard Value)

(Actual)

2.5 V

Open

2.5 V

7 V to 25 V

3.3 V

78.7 k

Ω

3.306 V

7 V to 33 V

PTN780x0W

5 V

21 k

Ω

4.996 V

7 V to 36 V

12 V

732

Ω

12.002 V

14.5 V to 36 V

12 V

383 k

Ω

12.000 V

15 V to 36 V

15 V

15 k

Ω

14.994 V

18 V to 36 V

PTN780x0H

18 V

4.42 k

Ω

18.023 V

21 V to 36 V

22 V

95.3

21.998 V

26 V to 36 V

10