A 16-channel, 12-bit PWM controller driven over I2C, the chip on nearly every servo-driver and RGB-LED breakout. Each of the 16 outputs has an independent 12-bit duty cycle and a programmable ON/OFF phase, so LEDs dim smoothly and hobby servos get their pulse without tying up microcontroller timers. One shared frequency (about 24 Hz to 1526 Hz) covers all channels, an external clock input allows tighter timing, and six address pins let up to 62 devices share the bus for almost a thousand channels. Outputs sink and source a few milliamps directly, or drive external FETs for power loads. Runs 2.3-5.5 V.

Pinout

Pin	Name	Type	Function
1	A0	input	I2C-bus hardware address input bit 0. No internal pull-up; must be tied HIGH or LOW.
2	A1	input	I2C-bus hardware address input bit 1. No internal pull-up; must be tied HIGH or LOW.
3	A2	input	I2C-bus hardware address input bit 2. No internal pull-up; must be tied HIGH or LOW.
4	A3	input	I2C-bus hardware address input bit 3. No internal pull-up; must be tied HIGH or LOW.
5	A4	input	I2C-bus hardware address input bit 4. No internal pull-up; must be tied HIGH or LOW.
6	LED0	output	LED driver channel 0. Software-selectable open-drain (25 mA sink @ 5 V) or totem-pole (25 mA sink / 10 mA source @ 5 V). Default POR state is LOW.
7	LED1	output	LED driver channel 1. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
8	LED2	output	LED driver channel 2. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
9	LED3	output	LED driver channel 3. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
10	LED4	output	LED driver channel 4. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
11	LED5	output	LED driver channel 5. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
12	LED6	output	LED driver channel 6. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
13	LED7	output	LED driver channel 7. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
14	VSS	power_in	Supply ground (0 V reference).
15	LED8	output	LED driver channel 8. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
16	LED9	output	LED driver channel 9. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
17	LED10	output	LED driver channel 10. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
18	LED11	output	LED driver channel 11. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
19	LED12	output	LED driver channel 12. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
20	LED13	output	LED driver channel 13. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
21	LED14	output	LED driver channel 14. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
22	LED15	output	LED driver channel 15. Software-selectable open-drain or totem-pole; 25 mA sink / 10 mA source at 5 V.
23	OE	input	Active-LOW output enable. When HIGH the LEDn outputs are programmable to logic 1, logic 0 (default at power-up), or high-impedance. Can be toggled to externally PWM/blink all outputs.
24	A5	input	I2C-bus hardware address input bit 5. No internal pull-up; must be tied HIGH or LOW.
25	EXTCLK	input	External clock input (50 MHz max). Replaces the internal 25 MHz oscillator when enabled; must be grounded when not used.
26	SCL	input	I2C-bus serial clock line. Fast-mode Plus (Fm+, up to 1 MHz) compatible; requires external pull-up.
27	SDA	bidirectional	I2C-bus serial data line. Open-drain with 30 mA sink capability for driving high-capacitance buses (up to 4000 pF); requires external pull-up.
28	VDD	power_in	Supply voltage, 2.3 V to 5.5 V. Inputs and LED outputs are 5.5 V tolerant.

Key specifications

Parameter	Value
Type	16-channel 12-bit PWM controller
Channels	16 (independent duty + phase)
Resolution	12-bit per channel
PWM frequency	24 Hz to 1526 Hz (shared)
Interface	I2C up to 1 MHz
Address pins	6 (up to 62 on a bus)
Output drive	~10-25 mA per channel
Package	TSSOP-28

Ordering variants

Same part, different packaging or reel option.

PCA9685PW (TSSOP-28)
PCA9685BS (HVQFN-28)

CAD (KiCad official)

Symbol: Driver_LED:PCA9685PW
Footprint: Package_SO:TSSOP-28_4.4x9.7mm_P0.65mm
3D model: TSSOP-28 (KiCad packages3D)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: NXP Semiconductors datasheet (52 pp, sha256 237d47f339cac4c3, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF