PCA9685 16-channel LED Controller Datasheet by NXP Semiconductors 2025

PCA9685 Overview

The PCA9685 is a 16-channel LED controller that operates via the I2C bus, offering precise PWM control for applications such as RGB(A) backlighting. Each output features a 12-bit resolution PWM generator, enabling fine-grained brightness control across 4096 steps. The PWM frequency is programmable from approximately 24 Hz to 1526 Hz, with all channels sharing the same frequency. The device supports both open-drain and totem-pole output configurations, providing a 25 mA sink and 10 mA source capability at 5 V. Operating within a supply voltage range of 2.3 V to 5.5 V, the PCA9685 is 5.5 V tolerant on both inputs and outputs, allowing direct LED connection or integration with external drivers for high-power applications. Additionally, as part of the Fast-mode Plus (Fm+) I2C family, it supports communication speeds up to 1 MHz and can operate on buses with capacitance up to 4000 pF.

Compared to the PCA9635, the PCA9685 introduces several enhancements, making it more suitable for backlighting and Ambilight applications. It supports staggered LED switching to reduce current surges, offers a wider PWM resolution of 12 bits instead of 8 bits, and includes a programmable prescaler to synchronize PWM pulse widths across multiple devices. A key feature is its external clock input, accepting frequencies up to 50 MHz for synchronization, whereas the PCA9635 lacks this capability. Additionally, the PCA9685 provides a more flexible PWM frequency range, making it compatible with external power controllers. Notably, its Power-On Reset (POR) state defaults to LOW on all LED outputs, contrasting with the PCA9635’s default HIGH state.

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