Application Notes

ATH Series of Wide-Output Adjust Power

Modules (3.3/5-V Input)

North America (USA): 1-888-41-ASTEC

Europe (UK): 44(1384)842-211

Asia (HK): 852-2437-9662

Margin Up/Down Controls

The ATH10 (10A), ATH12/15 (12/15A), ATH18/22 (18/

22A) and ATH26/30 (26/30A) products incorporate Margin

Up and Margin Down control inputs. These controls allow

or down, by a nominal 5 %. This provides a convenient

method for dynamically testing the operation of the load

circuit over its supply margin or range. It can also be used to

verify the function of supply voltage supervisors. The

±5 % change is applied to the adjusted output voltage, as set

The 5 % adjustment is made by pulling the appropriate

A low-leakage open-drain device, such as an n-channel

MOSFET or p-channel JFET is recommended for this

modated by adding series resistors to the control inputs

(See Figure 3-4). The value of the resistor can be selected

from Table 3-2, or calculated using the following formula.

Up/Down Adjust Resistance Calculation

To reduce the margin adjustment to something less than

Figure 3-7). For the same amount of adjustment, the

The formulas is as follows.

R

499

– 99.8

k

Ω

∆%

Where

∆% = The desired amount of margin adjust in

percent.

Notes:

1. The Margin Up* and Margin Dn* controls were not

intended to be activated simultaneously. If they are

their affects on the output voltage may not completely

cancel, resulting in the possibility of a slightly higher

error in the output voltage set point.

2. The ground reference should be a direct connection to

the module GND at pin 7 (pin 1 for the ATH06).

This will produce a more accurate adjustment at the

be located close to the regulator.

3. The Margin Up and Margin Dn control inputs are not

compatible with devices that source voltage. This includes

TTL logic. These are analog inputs and should only be

controlled with a true open-drain device (preferably

a discrete MOSFET transistor). The device selected

should have low off-state leakage current. Each input

sources 8 µA when grounded, and has an open-circuit

voltage of 0.8 V.

Figure 3-7; Margin Up/Down Application Schematic

Table 3-2; Margin Up/Down Resistor Values

% Adjust

5

0.0 k

Ω

4

24.9 k

Ω

3

66.5 k

Ω

2

150.0 k

Ω

1

397.0 k

Ω

C

out

+

C

in

V

IN

GND

MargDn

L

O

A

D

Q

2

+V

OUT

Q

1

+

MargUp

0V

+V

o

R

D

R

U

PTH05010W

(Top View)

1

2

10 9

8

7

6

5

4

3

GND

R

SET

0.1 W, 1 %

ATH15T05-9S