PT6344 datasheet(7/9 Pages) TI

7 / 9 page

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

for each model for either series as Va (min) and Va (max).

Adjust Up:

An increase in the output voltage is obtained by

adding a resistor R2, between pin 12 (Vo adj) and pins 5-8

(GND).

Adjust Down:

Add a resistor (R1), between pin 12 (Vo adj) and

pins 9-11 (Vo).

Figure 1

The values of (R1) [adjust down], and R2 [adjust up], can

also be calculated using the following formulas. Refer to

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

required resistor; either (R1) or R2 as appropriate.

(R1)

Ro (Va – Vr)

– Rs

Ω

Vo – Va

Vr · Ro

– Rs

Ω

Va – Vo

Where:

Vo = Original output voltage

Va = Adjusted output voltage

Vr = Reference voltage (Table 1)

Ro = Resistance constant (Table 1)

Rs = Internal series resistance (Table 1)

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

0.8

Ro (k

Ω

Ω)

10.0

Rs (k

Ω)

24.9

Adjust Up

COM

(R1)

Adj Down

PT6340

2,3,4

5–812

9,10,11

Vin

V o

Vo(adj)

GND

Notes:

1. Use only a single 1% resistor in either the (R1) or R2

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

2. Never connect capacitors from Vo adj to either GND or

Vout. Any capacitance added to the Vo adjust pin will

affect the stability of the ISR.

PT6344 Datasheet(PDF) 7 Page - Texas Instruments

PT6344 Datasheet(HTML) 7 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9

Datasheet Download

Link URL