Technical Reference Notes

APC12 Centauri II

MODEL: APC12 SERIES

SHEET 11 OF 23

JANUARY 6, 2002 REVISION A (PRELIMINARY)

Trim Function (continued)

Method 2: External DC Source

By connecting an external DC supply across P4 (Enable) and P3 (GND) through a limiting resistor Rt, (see Figure 5), output

voltage adjustment can also be achieved. Equation 3 provides the relationship between the External DC supply, Vt, and Vo

(where Vo is the desired output voltage).

Given: Rt = 10k

Ω

Vo Adjustment to Lower Voltages. This method does not limit the recommended lower Vo adjustment to 2% as mentioned

on previous sections re: Vo adjustment through external trim resistor.

Example:

Module version: APC08G03-9 (3V to 6Vin, 2.5Vo).

Requiring to adjust the output voltage from Vo = 2.5V to 1.8V

Example:

Module version: APC08G03-9 (3V to 6Vin, 2.5Vo).

Requiring to adjust the output voltage from Vo = 2.5V to 0.9V

Vo Adjustment to Higher Voltages

Example:

Module version: APC08G03-9 (3V to 6Vin, 2.5Vo).

Requiring to adjust the output voltage from Vo = 2.5V to 3.3V

If application of negative voltage is not desired, the limiting resistor Rt can either be changed to a lower value (Rt = 1k

Ω

Ω

Ω

Ω, such

that Vt = 0.60V per Equation 3), or use Method 1.

Vo

R

Rt

Vref

R

Rt

R

Rt

Vt

1

2

1

1

−













+

+

=

Equation (3)

Figure 5. External DC source for output trim adjust.