controller. PCA9685 Datasheet

PCA9685 Datasheet PDF

Part PCA9685
Description 12-bit PWM Fm I2C-bus LED controller
Feature PCA9685 16-channel, 12-bit PWM Fm+ I2C-bus LED controller Rev. 4 — 16 April 2015 Product data she.
Manufacture NXP Semiconductors
Download PCA9685 Datasheet

PCA9685 16-channel, 12-bit PWM Fm+ I2C-bus LED controller PCA9685 Datasheet

16-channel, 12-bit PWM Fm+ I2C-bus LED controller
Rev. 4 — 16 April 2015
Product data sheet
1. General description
The PCA9685 is an I2C-bus controlled 16-channel LED controller optimized for
Red/Green/Blue/Amber (RGBA) color backlighting applications. Each LED output has its
own 12-bit resolution (4096 steps) fixed frequency individual PWM controller that operates
at a programmable frequency from a typical of 24 Hz to 1526 Hz with a duty cycle that is
adjustable from 0 % to 100 % to allow the LED to be set to a specific brightness value.
All outputs are set to the same PWM frequency.
Each LED output can be off or on (no PWM control), or set at its individual PWM controller
value. The LED output driver is programmed to be either open-drain with a 25 mA current
sink capability at 5 V or totem pole with a 25 mA sink, 10 mA source capability at 5 V. The
PCA9685 operates with a supply voltage range of 2.3 V to 5.5 V and the inputs and
outputs are 5.5 V tolerant. LEDs can be directly connected to the LED output (up to
25 mA, 5.5 V) or controlled with external drivers and a minimum amount of discrete
components for larger current or higher voltage LEDs.
The PCA9685 is in the new Fast-mode Plus (Fm+) family. Fm+ devices offer higher
frequency (up to 1 MHz) and more densely populated bus operation (up to 4000 pF).
Although the PCA9635 and PCA9685 have many similar features, the PCA9685 has
some unique features that make it more suitable for applications such as LCD or LED
backlighting and Ambilight:
The PCA9685 allows staggered LED output on and off times to minimize current
surges. The on and off time delay is independently programmable for each of the
16 channels. This feature is not available in PCA9635.
The PCA9685 has 4096 steps (12-bit PWM) of individual LED brightness control. The
PCA9635 has only 256 steps (8-bit PWM).
When multiple LED controllers are incorporated in a system, the PWM pulse widths
between multiple devices may differ if PCA9635s are used. The PCA9685 has a
programmable prescaler to adjust the PWM pulse widths of multiple devices.
The PCA9685 has an external clock input pin that will accept user-supplied clock
(50 MHz max.) in place of the internal 25 MHz oscillator. This feature allows
synchronization of multiple devices. The PCA9635 does not have external clock input
Like the PCA9635, PCA9685 also has a built-in oscillator for the PWM control.
However, the frequency used for PWM control in the PCA9685 is adjustable from
about 24 Hz to 1526 Hz as compared to the typical 97.6 kHz frequency of the
PCA9635. This allows the use of PCA9685 with external power supply controllers. All
bits are set at the same frequency.
The Power-On Reset (POR) default state of LEDn output pins is LOW in the case of
PCA9685. It is HIGH for PCA9635.

NXP Semiconductors
16-channel, 12-bit PWM Fm+ I2C-bus LED controller
The active LOW Output Enable input pin (OE) allows asynchronous control of the LED
outputs and can be used to set all the outputs to a defined I2C-bus programmable logic
state. The OE can also be used to externally ‘pulse width modulate’ the outputs, which is
useful when multiple devices need to be dimmed or blinked together using software
Software programmable LED All Call and three Sub Call I2C-bus addresses allow all or
defined groups of PCA9685 devices to respond to a common I2C-bus address, allowing
for example, all red LEDs to be turned on or off at the same time or marquee chasing
effect, thus minimizing I2C-bus commands. Six hardware address pins allow up to
62 devices on the same bus.
The Software Reset (SWRST) General Call allows the master to perform a reset of the
PCA9685 through the I2C-bus, identical to the Power-On Reset (POR) that initializes the
registers to their default state causing the outputs to be set LOW. This allows an easy and
quick way to reconfigure all device registers to the same condition via software.
2. Features and benefits
16 LED drivers. Each output programmable at:
Programmable LED brightness
Programmable LED turn-on time to help reduce EMI
1 MHz Fast-mode Plus compatible I2C-bus interface with 30 mA high drive capability
on SDA output for driving high capacitive buses
4096-step (12-bit) linear programmable brightness per LED output varying from fully
off (default) to maximum brightness
LED output frequency (all LEDs) typically varies from 24 Hz to 1526 Hz (Default of 1Eh
in PRE_SCALE register results in a 200 Hz refresh rate with oscillator clock of
25 MHz.)
Sixteen totem pole outputs (sink 25 mA and source 10 mA at 5 V) with software
programmable open-drain LED outputs selection (default at totem pole). No input
Output state change programmable on the Acknowledge or the STOP Command to
update outputs byte-by-byte or all at the same time (default to ‘Change on STOP’).
Active LOW Output Enable (OE) input pin. LEDn outputs programmable to logic 1,
logic 0 (default at power-up) or ‘high-impedance’ when OE is HIGH.
6 hardware address pins allow 62 PCA9685 devices to be connected to the same
Toggling OE allows for hardware LED blinking
4 software programmable I2C-bus addresses (one LED All Call address and three LED
Sub Call addresses) allow groups of devices to be addressed at the same time in any
combination (for example, one register used for ‘All Call’ so that all the PCA9685s on
the I2C-bus can be addressed at the same time and the second register used for three
different addresses so that 13 of all devices on the bus can be addressed at the same
time in a group). Software enable and disable for these I2C-bus address.
Software Reset feature (SWRST General Call) allows the device to be reset through
the I2C-bus
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 4 — 16 April 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
2 of 52

@ 2014 :: ::
Semiconductors datasheet search & download site (Privacy Policy & Contact)