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  • LED
  • VDD
  • SCL and SDA Pins
  • I2CSPD Pin
  1. Datasheet

Pin Description

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Last updated 19 days ago

LED

3.3 V Addressable LED Data Pin.

The Addressable LED Data Pin operates at 3.3 V. However, addressable LEDs typically require a 5 V logic level, so a non-inverting buffer is needed to shift the signal from 3.3 V to 5 V. There are many suitable buffers available; in the implementation guide chapter, the 74LVC1G17 is used.

VDD

3.3 V Power Supply Pin.

A decoupling capacitor should be placed on the power pin. It is recommended to use a 100nF, 10-25V low-ESR ceramic capacitor.

SCL and SDA Pins

I2C-Compatible Bus Interface Pins.

SCL (Serial Clock Line): This pin is used to synchronize data transfer between the IS3750 device and the Microcontroller or other CPU.

SDA (Serial Data Line): This bidirectional pin is used for both sending and receiving data between the IS3750 and the Microcontroller or other CPU.

Both pins are open-drain and must be pulled up to 3.3V or 5V. The pull-up resistor value should be chosen based on the bus speed and capacitance. Typical values are 4.7kΩ for Standard Mode (100kbps) and 2.2kΩ for Fast Mode (400kbps) at both 3.3V and 5V.

I2CSPD Pin

I2C-Serial Interface Speed Selection Pin.

This pin configures the IS3750 internal I2C-Serial Interface timings and filters to properly work with the selected bus speed.

- For a 100kHz setting, set the I2CSPD pin to VSS.

- For a 400kHz setting, set the I2CSPD to 1.65V (VDD/2) using a balanced voltage divider. This can be achieved by placing two 4.7kΩ resistors from the I2CSPD pin: one to VDD and the other to VSS.

- For a 1000MHz setting, set the I2CSPD pin to VDD.

Important Remark:

A mismatch between the configured I2C speed and the actual operating I2C speed (e.g., configuring the bus for 100kHz but operating at 1MHz) can lead to an inconsistent state where some I2C messages are processed while others are not.

Ensure a proper match between the actual operating speed and the configured speed at the I2CSPD pin: If your bus works at 100kHz, ensure the I2CSPD pin is tied to VSS. If it works at 400kHz ensure the pin is at 1.65V. If it works at 1000MHz, ensure the pin is at 3.3V.

IS3750 Pinout
IS3750 Pinout Description
IS3750 I2C at 100 kHz
IS3750 I2C at 400 kHz
IS3750 I2C at 1 MHz