ADM8845

Rev. 0 | Page 12 of 20

The ADM8845’s main and sub display brightness can be

controlled together or separately by applying a digital PWM

signal to both CTRL1 and CTRL2 pins. The duty cycle of the

applied digital PWM signal determines the brightness of the

main and sub displays together. Varying the duty cycle of the

applied PWM signal also varies the brightness of the main and

sub displays from 0% to 100%.

By holding CTRL1 low and applying a digital PWM signal to

CTRL2, the sub display is turned off and the main display is

turned on. Then the brightness of the main display is determined

by the duty cycle of the applied digital PWM signal.

By applying a digital PWM signal to CTRL1 and holding CTRL2

low, the sub display is turned on and the main display is turned

off. Then the brightness of the sub display is determined by the

duty cycle of the applied digital PWM signal.

By applying a digital PWM signal to CTRL1 and holding CTRL2

high, the sub display is turned on and the main display is turned

on. Then the brightness of the sub display is determined by the

duty cycle of the applied digital PWM signal. The brightness of

By holding CTRL1 high and applying a digital PWM signal to

CTRL2, the sub display is turned on and the main display is

turned on. Then the brightness of the main display is determined

by the duty cycle of the applied digital PWM signal. The bright-

ness of the sub display is set to the maximum (maximum is set

When CTRL1 and CTRL2 go low, the LED current control

sinks shutdown. Shutdown of the charge pump is delayed by

determine if a digital PWM signal is present on CTRL1 and

CTRL2 or if the user has selected a full chip shutdown (see

Figure 25).

If digital PWM brightness control of the LEDs is not required, a

The six white LED in the ADM8845 are arranged in two groups,

sub and main. It is possible to configure the six LEDs as in

Table 7; refer also to Figure 25.

Table 7. Digital Inputs Truth Table

CTRL1

CTRL2

LED Operation

0

0

Sub Display Off / Main Display Off (Full Shutdown)1, 2

0

1

Sub Display Off / Main Display On1, 3

1

0

Sub Display On / Main Display Off1, 2

1

1

Sub Display On / Main Display On (Full On) 1, 3

0

PWM

Sub Display Off/ Digital PWM Brightness Control on Main Display4, 5

PWM

0

Digital PWM Brightness Control on Sub Display / Main Display Off2, 4

1

PWM

Sub Display On/ Digital PWM Brightness Control on Main Display1, 5

PWM

1

Digital PWM Brightness Control on Sub Display / Main Display On5

PWM

PWM

Digital PWM Brightness Control on Sub and Main Display

5