pca9685 NXP Semiconductors, pca9685 Datasheet - Page 13

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

NXP Semiconductors
Table 4.
Legend: * default value.
[1]
[2]
[3]
[4]
PCA9685_1
Product data sheet
Bit
7
6
5
4
3
2
1
0
When the Auto Increment flag is set, AI = 1, the Control register is automatically incremented after a read or write. This allows the user
to program the registers sequentially.
It takes 500 s max. for the oscillator to be up and running once SLEEP bit has been set to logic 0. Timings on LEDn outputs are not
guaranteed if PWM control registers are accessed within the 500 s window. There is no start-up delay required when using the
EXTCLK pin as the PWM clock.
No PWM control is possible when the oscillator is off.
When the oscillator is off (Sleep mode) the LEDn outputs cannot be turned on, off or dimmed/blinked.
Symbol
RESTART
EXTCLK
AI
SLEEP
SUB1
SUB2
SUB3
ALLCALL
MODE1 - Mode register 1 (address 00h) bit description
7.3.1 Mode register 1, MODE1
Access
R
W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Value
0*
1
0*
1
0*
1
0
1*
0*
1
0*
1
0*
1
0
1*
Description
Shows state of RESTART logic. See
User writes logic 1 to this bit to clear it to logic 0. A user write of logic 0 will have no
effect. See
Restart disabled.
Restart enabled.
To use the EXTCLK pin, this bit must be set by the following sequence:
This bit is a ‘sticky bit’, that is, it cannot be cleared by writing a logic 0 to it. The
EXTCLK bit can only be cleared by a power cycle or software reset.
EXTCLK range is DC to 50 MHz.
Use internal clock.
Use EXTCLK pin clock.
Register Auto-Increment disabled
Register Auto-Increment enabled.
Normal mode
Low power mode. Oscillator off
PCA9685 does not respond to I
PCA9685 responds to I
PCA9685 does not respond to I
PCA9685 responds to I
PCA9685 does not respond to I
PCA9685 responds to I
PCA9685 does not respond to LED All Call I
PCA9685 responds to LED All Call I
1. Set the SLEEP bit in MODE1. This turns off the internal oscillator.
2. Write logic 1s to both the SLEEP and EXTCLK bits in MODE1. The switch is
refresh_rate
now made. The external clock can be active during the switch because the
SLEEP bit is set.
Rev. 01 — 24 July 2008
Section 7.3.1.1
[2]
.
=
-------------------------------------------------------
4096
16-channel, 12-bit PWM Fm+ I
2
2
2
C-bus subaddress 1.
C-bus subaddress 2.
C-bus subaddress 3.
EXTCLK
prescale
for detail.
[3][4]
2
2
2
C-bus subaddress 1.
C-bus subaddress 2.
C-bus subaddress 3.
[1]
.
.
+
2
Section 7.3.1.1
C-bus address.
1
2
C-bus address.
for detail.
2
C-bus LED controller
PCA9685
© NXP B.V. 2008. All rights reserved.
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