Technical Reference Notes

APC12 Centauri II

MODEL: APC12 SERIES

SHEET 10 OF 23

JANUARY 6, 2002 REVISION A (PRELIMINARY)

Trim Function (continued)

To adjust Vo to a higher value, please refer to

Figure 4. The required resistor value (Rt) can be

determined through Equation (1) where Vo is the

voltage on P2 before the adjustment and Vot is the

voltage of P2 after Rt is connected.

1

R

Vo

Vot

Vref

Rt

−

=

Equation (1)

Please refer to related constants given in TABLE 1 to calculate the Equation.

TABLE 1. CONSTANTS

Version

0.9V

1.2V

1.5V

1.8V

2.5V

3.3V

R1

APC08/12x03

R2

97.6k

8.45k

4.32k

2.94k

1.69k

1.13k

3.09k

APC08/12x08

R2

210k

17.4k

9.09k

6.04k

3.48k

2.32k

6.49k

0.87V

Be aware that the maximum Vo allowed is 3.6V. Please refer to Centauri datasheet.

Example:

Module version: APC08J03-9 (1.8 to 6.0Vin, 0.9Vo).

Ω (from TABLE 1).

Based on Equation (1), Rt can be determined as 3.0k

Ω.

To adjust Vo to a lower value, Rt should be connected between P4 and P2. Equation (2) provides the calculation for Rt.

2

)

(

)

)(

(

R

V

V

V

V

V

V

V

Rt

ot

o

ref

ref

ot

ref

o

−

−

−

=

Equation (2)

Be aware that the minimum Vo is 0.9V.

Example

Module version: APC08F03-9 (4.0 to 6.Vin, 3.3Vo).

Requiring to adjust the output voltage from Vo = 3.3V to Vot = 3.3 (1-0.02) = 3.234V.

Ω (from TABLE 1).

Based on Equation (1), Rt can be determined as 111.9k

Ω.

Figure 4. Output Voltage Trim Setup.