16-Bit Fm+ I²C-Bus LED Driver
The PCA9635 is an I²C-bus controlled 16-bit LED driver optimized for Red/Green/Blue/Amber (RGBA) color mixing applications. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 97 kHz with a duty cycle that is adjustable from 0 pct to 99.6 pct to allow the LED to be set to a specific brightness value. An additional 8-bit resolution (256 steps) group PWM controller has both a fixed frequency of 190 Hz and an adjustable frequency between 24 Hz to once every 10.73 seconds with a duty cycle that is adjustable from 0 pct to 99.6 pct that is used to either dim or blink all LEDs with the same value.
Each LED output can be off, on (no PWM control), set at its individual PWM controller value or at both individual and group PWM controller values. 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 PCA9635 operates with a supply voltage range of 2.3 V to 5.5 V and the 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 PCA9635 is one of the first LED controller devices in a 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).
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 PWM the outputs, which is useful when multiple devices need to be dimmed or blinked together using software control.
Software programmable LED Group and three Sub Call I²C-bus addresses allow all or defined groups of PCA9635 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. Seven hardware address pins allow up to 126 devices on the same bus.
The Software Reset (SWRST) Call allows the controller to perform a reset of the PCA9635 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 HIGH (LED off). This allows an easy and quick way to reconfigure all device registers to the same condition.
Product Details
Features
Key Features
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16 LED drivers. Each output programmable at:
- Off
- On
- Programmable LED brightness
- Programmable group dimming/blinking mixed with individual LED brightness
- 1 MHz Fast-mode Plus compatible I²C-bus interface with 30 mA high drive capability on SDA output for driving high capacitive buses
- 256-step (8-bit) linear programmable brightness per LED output varying from fully off (default) to maximum brightness using a 97 kHz PWM signal
- 256-step group brightness control allows general dimming (using a 190 Hz PWM signal) from fully off to maximum brightness (default)
- 256-step group blinking with frequency programmable from 24 Hz to 10.73s and duty cycle from 0 pct to 99.6 pct
- 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 function
- 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. LED outputs programmable to logic 1, logic 0 or 'high-impedance' (default at power-up) when OE is HIGH, thus allowing hardware blinking and dimming of the LEDs
- 7 hardware address pins allow 126 devices to be connected to the same I²C-bus
- 4 software programmable I²C-bus addresses (one LED Group 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 PCA9635s on the I²C-bus can be addressed at the same time and the second register used for three different addresses so that 1/3 of all devices on the bus can be addressed at the same time in a group). Software enables and disables for I²C-bus address
- Software Reset feature (SWRST Call) allows the device to be reset through the I²C-bus
- 25 MHz internal oscillator requires no external components
- Internal power-on reset
- Noise filter on SDA/SCL inputs
- Edge rate control on outputs
- No glitch on power-up
- Supports hot insertion
- Low standby current
- Operating power supply voltage range of 2.3 V to 5.5 V
- 5.5 V tolerant inputs
- -40 Cel to +85 Cel operation
- ESD protection exceeds 2000 V HBM per JESD22-A114, 200 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101
- Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
- Packages offered: TSSOP28
Buy/Parametrics
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