Datasheet

EVAL-ADM8845 Preliminary Technical Data
8 REV. PrB 02/05
SETTING UP THE ADM8845 EVAL BOARD
Insert the following links to evaluate the ADM8845 with both the main and sub display on with approx. 20mA per LED:
1. Insert LK1 – LK6, this attaches all 6 LEDS to the Vout pin (Pin 3) of the ADM8845 chip. We are now going to operate the ADM8845
Eval Board with 6 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 ADM8845 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 LK1 – LK6, this attaches all 6 LEDS to the Vout pin (Pin 3) of the ADM8845 chip. We are now going to operate the ADM8845
Eval Board with 6 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 ADM8845
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 ADM8845/6 Software GUI and program the digital PWM frequency and duty cycle as required.
ADM8845
CTRL1
CTRL1
Vout
FB2
FB3
FB4
FB5
FB6
FB1
C3
C3+
C3-
2.2␮F
Iset
Rset
C1
1␮F
C2
1␮F
PWM Input
or
High/Low
PWM Input
or
High/Low