PCA9685BS NXP [NXP Semiconductors], PCA9685BS Datasheet - Page 14

• Manufacturer Part Number: PCA9685BS
• Description: 16-channel, 12-bit PWM Fm+ I2C-bus LED controller
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
1.
PCA9685_2
Product data sheet
Two methods can be used to do an orderly shutdown. The fastest is to write a logic 1 to bit 4 in register ALL_LED_OFF_H. The
other method is to write logic 1 to bit 4 in each active PWM channel LEDn_OFF_H register.
7.3.1.1 Restart mode
If the PCA9685 is operating and the user decides to put the chip to sleep (setting MODE1
bit 4) without stopping any of the PWM channels, the RESTART bit (MODE1 bit 7) will be
set to logic 1 at the end of the PWM refresh cycle. The contents of each PWM register are
held valid when the clock is off.
To restart all of the previously active PWM channels with a few I
following steps:
Remark: The SLEEP bit must be logic 0 for at least 500 s, before a logic 1 is written into
the RESTART bit.
Other actions that will clear the RESTART bit are:
Likewise, if the user does an orderly shutdown
SLEEP bit, the RESTART bit will be cleared. If this is done the contents of all PWM
registers are invalidated and must be reloaded before reuse.
An example of the use of the RESTART bit would be the restoring of a customer’s laptop
LCD backlight intensity coming out of Standby to the level it was before going into
Standby.
1. Read MODE1 register.
2. Check that bit 7 (RESTART) is a logic 1. If it is, clear bit 4 (SLEEP). Allow time for
3. Write logic 1 to bit 7 of MODE1 register. All PWM channels will restart and the
1. Power cycle.
2. I
3. If the MODE2 OCH bit is logic 0, write to any PWM register then issue an I
4. If the MODE2 OCH bit is logic 1, write to all four PWM registers in any PWM channel.
oscillator to stabilize (500 s).
RESTART bit will clear.
STOP.
2
C Software Reset command.
Rev. 02 — 16 July 2009
16-channel, 12-bit PWM Fm+ I
1
of all the PWM channels before setting the
2
C-bus cycles do the
2
C-bus LED controller
PCA9685
© NXP B.V. 2009. All rights reserved.
2
C-bus
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