pca9685 NXP Semiconductors, pca9685 Datasheet - Page 26

• Manufacturer Part Number: pca9685
• Description: 16-channel, 12-bit Pwm Fm+ I 2c-bus Led Controller
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9685_1
Product data sheet
7.4 Active LOW output enable input
7.5 Power-on reset
The active LOW output enable (OE) pin, allows to enable or disable all the LED outputs at
the same time.
Table 10.
The OE pin can be used as a synchronization signal to switch on/off several PCA9685
devices at the same time. This requires an external clock reference that provides blinking
period and the duty cycle.
The OE pin can also be used as an external dimming control signal. The frequency of the
external clock must be high enough not to be seen by the human eye, and the duty cycle
value determines the brightness of the LEDs.
When power is applied to V
condition until V
PCA9685 registers and I
Thereafter, V
OUTNE1
0
0
1
1
•
•
When a LOW level is applied to OE pin, all the LED outputs are enabled and follow the
output state defined in the LEDn_ON and LEDn_OFF registers with the polarity
defined by INVRT bit (MODE2 register).
When a HIGH level is applied to OE pin, all the LED outputs are programmed to the
value that is defined by OUTNE[1:0] in the MODE2 register.
LED outputs when OE = 1
DD
OUTNE0
0
1
0
1
DD
must be lowered below 0.2 V to reset the device.
has reached V
Rev. 01 — 24 July 2008
2
C-bus state machine are initialized to their default states.
DD
LED outputs
0
1 if OUTDRV = 1, high-impedance if OUTDRV = 0
high-impedance
high-impedance
, an internal power-on reset holds the PCA9685 in a reset
POR
16-channel, 12-bit PWM Fm+ I
. At this point, the reset condition is released and the
2
C-bus LED controller
PCA9685
© NXP B.V. 2008. All rights reserved.
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