Analysis of 8-channel IIC interface LED driver AT9551

Crystal oscillator

Quartz Oscillator 3225 20M OSC

As a direct replacement for the PCA9551, the AT9551 provides the ability to drive eight parallel LEDs for backlight and RGB color mixing applications. This device can also individually turn on, turn off or flash each LED (the flashing frequency is available in two programmable options), with an integrated oscillator circuit inside and a programmable flash control drive. In addition, the device can also implement sensor control, power switch, switch button and status indication illumination through I2C or SMBus interface.

Product Features:

● Drive 8 LEDs and provide programmable flash function;

● Internal power-on reset;

● 8 open-drain outputs, each with a drive current of 25mA;

● Two programmable flashing frequencies: 0.15625 Hz to 40 Hz (*/0.025 seconds);

● Internal integrated oscillator circuit, no external components required;

● Operating voltage range: 2.3V~5.5V;

● I/O can be used as a general purpose I/O port;

● Support hot plugging;

●Low standby circuit

● Compatible with 400kHz I2C bus specification;

● Package: 16-pin SOP, TSSOP or 16-pad TQFN package (size 4x4mm)

[PQI SDXC Class10 Product Specifications]:

● Transmission speed: Class10

● Capacity: 64GB

● Size: 32 x 24 x 2.1 (mm)

● Warranty time: lifetime warranty

Functional block diagram

Typical application circuit