Datasheet

EVAL-ADM8843 Preliminary Technical Data

8 REV. PrC 02/05

SETTING UP THE ADM8843 EVAL BOARD

Insert the following links to evaluate the ADM8843 with both the main and sub display on with approx. 20mA per LED:

1. Insert LK2 – LK5, this attaches all 4 LEDS to the Vout pin (Pin 3) of the ADM8843 chip. We are now going to operate the ADM8843

Eval Board with 4 LEDs in parallel.

2. Insert LK7 A and LK8 A. This turns on both the main and sub display.

3. Insert LK10 B. This connect a 7.32K Ohm resistor to the I

SET

pin. This will give approx. 20mA per LED.

1.18V/7.32kOhm = 161.20µA. This is then scaled up by 120 to give 161.20µA * 120 = 19.344mA per LED

4. Remove all other Links

5. Apply power to Power Connector J1 (3V Nominal)

Insert the following links to evaluate the ADM8843 part with both the main and sub display on with approx. 20mA per LED, brightness

controlled by a digital PWM signal applied to both CTRL1 and CTRL2:

1. Insert LK2 – LK5 this attaches all 4 LEDS to the Vout pin (Pin 3) of the ADM8843 chip. We are now going to operate the ADM8843

Eval Board with 4 LEDs in parallel.

2. Insert LK7 D and LK8 D. This turns on both the main and sub display for digital PWM brightness control.

3. Insert LK10 B. This connect a 7.32K Ohm resistor to the I

SET

pin. This will give approx. 20mA per LED.

1.18V/7.32kOhm = 161.20µA. This is then scaled up by 120 to give 161.20µA * 120 = 19.344mA per LED

4. Insert LK11 A, LK12 A and LK13 A, this connect the ADuC832 to the software GUI to program the digital PWM frequency and duty

cycle.

5. Remove all other Links

6. Apply power to Power Connector J1 (3V Nominal). This power up the ADM8843

7. Apply power to Power Connector J10 (3V Nominal). This powers up the ADuC832 which provides the digital PWM signal to CTRL1

and CTRL2.

8. Attach the PC cable provided to the parallel port of a PC and the Eval Board.

9. Open up the ADM8843/5 Software GUI and program the digital PWM frequency and duty cycle as required.

ADM8843

CTRL1

CTRL2

Vo ut

FB 2

FB 3

FB4

FB1

Iset

Rset

C1 C2

PWM Input

High/Low

PWM Input

High/Low