Application Notes

For technical support and more information, see inside back cover or visit www.ti.com

PT6340 Series

Adjusting the Output Voltage of the PT6340

Excalibur

 6 A, 12 V Bus Step-Down ISRs

The output voltage of the PT6340 Series ISRs may be

adjusted higher or lower than the factory trimmed pre-

set voltage with the addition of a single external resistor.

Table 1 accordingly gives the allowable adjustment range

Adjust Up:

An increase in the output voltage is obtained by

(GND).

Adjust Down:

Figure 1

also be calculated using the following formulas. Refer to

Figure 1 and Table 2 for both the placement and value of the

=

k

Ω

=

k

Ω

Where:

Table 1

ISR ADJUSTMENT RANGE AND FORMULA PARAMETERS

Series Pt #

PT6341

PT6342

PT6343

PT6244

PT6345

PT6346

Vo (nom)

5.0

3.3

2.5

1.8

1.5

1.2

Va (min)

4.0

2.8

2.2

1.7

1.45

1.1

Va (max)

5.5

3.8

3.0

2.3

2.0

1.45

Vr (V)

1.27

1.27

1.27

1.27

1.27

0.8

Ro (k

Ω

Ω

Ω

Ω

Ω)

10.0

10.0

10.0

10.0

10.0

10.0

Rs (k

Ω)

24.9

24.9

24.9

24.9

24.9

24.9

R2

Adjust Up

C

2

+V

O

COM

COM

+V

IN

+

(R1)

Adj Down

PT6340

2,3,4

5–812

9,10,11

Vin

V o

Vo(adj)

GND

C

1

+

Notes:

location. Place the resistor as close to the ISR as possible.

affect the stability of the ISR.