ADM8845 Ver la hoja de datos (PDF) - Analog Devices
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ADM8845 Datasheet PDF : 20 Pages
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ADM8845
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
the main display is set to the maximum (maximum is set by RSET).
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
by RSET).
When CTRL1 and CTRL2 go low, the LED current control
sinks shutdown. Shutdown of the charge pump is delayed by
15 ms. This timeout period (tCP) allows the ADM8845 to
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
constant Logic Level 1 (VCC) or 0 (GND) must be applied.
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 Display5
1 Sub Display On means the display is on with the maximum brightness set by the RSET resistor. CTRL1 = 1 means a constant logic level (VCC) is applied to CTRL1.
2 Main Display Off means the main display only is off. CTRL2 = 0 means a constant logic level (GND) is applied to CTRL2.
3 Main Display On means the display is on with the maximum brightness set by the RSET resistor. CTRL2 = 1 means a constant logic level (VCC) is applied to CTRL2.
4 Sub Display Off means the sub display LEDs only is off. CTRL1 = 0 means a constant logic level (GND) is applied to CTRL1.
5 PWM means a digital PWM signal is applied to the CTRL1 and/or the CTRL2 pin with a frequency from 100 Hz to 200 kHz.
Rev. 0 | Page 12 of 20
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