Technical Reference Notes

ALD12/18/20/25 Series

(Single Output 16

MODEL: ALD12/18/20/25 SERIES

SHEET 6 OF 20

AUGUST 17, 2005 – REVISION C

+Vin

-Vin

Enable

-Vout

+Vout

-Sense

+Sense

Vadj

Rload

Radj_up

Figure 3. External resistor configuration to increase the outputs

+Vin

-Vin

Enable

-Vout

+Vout

-Sense

+Sense

Vadj

Rload

Radj_down

Figure 4. External resistor configuration to increase the outputs

Basic Operation and Features

INPUT UNDER VOLTAGE LOCKOUT

OUTPUT VOLTAGE ADJUST/TRIM

The converter comes with a TRIM pin (PIN 6), which is used to adjust the output by as much as 90% to 110% of its set point. This

is achieved by connecting an external resistor as described below.

should be connected between TRIM PIN (Pin6) and

+SENSE PIN (Pin 7). Please refer to Equation (1) for the

required external resistance and output adjust

relationship.

Equation (1a): 1.5V to 5V

Equation (1b): 1.2V

should be connected between TRIM pin (Pin 6) and

-SENSE PIN (Pin 5). Please refer to Equation (2) for the

required external resistance and output adjust

relationship.

Equation (2):

Where:

∆% = percent change in output voltage

OUTPUT ENABLE

The converter comes with an Enable pin (PIN 2), which is primarily used to turn ON/OFF the converter. Both a Positive (no “N”

suffix required) and a Negative (suffix “N” required) Enable Logic options are being offered.

Radj_down

510

∆%

10.2

−









k

Ω

⋅

Radj_up

5.1

Voset

×

100

∆%

+

()

×

0.6

∆%

×

510

∆%

−

10.2

−













=ΚΩ

Radj_up

5.1

Voset

×

100

∆%

+

()

×

1.225

∆%

×

510

∆%

−

10.2

−













=ΚΩ