TCA9800DGKT Integrated Circuits (ICs)

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1. Describe

The TCA9800DGKT is a dual bidirectional buffer for I2C bus and SMBus/PMBus systems. It provides bidirectional level translation (up and down translation) between low voltage (as low as 0.8V) and high voltage (1.65V to 3.6V). The TCA9800DGKT has an internal current source on the B side of the device, allowing the removal of the external pull-up resistor on the B side. The current source also provides improved rise time and ultra-low power consumption. The TCA9800 is able to provide true buffering (rather than a FET solution) without the use of static voltage offset or incremental offset. This means that the VOL on both the A and B sides of the TCA9800 is very low (~0.2 V), helping to eliminate communication problems caused by fixed VIL thresholds. Another key feature of the TCA9800 is that there are no power sequencing requirements or power dependencies. VCCA can be greater than, less than or equal to VCCB. This provides system designers the flexibility to use the TCA9800. The TCA9800 is part of a family of four devices with different current source strengths.

2. Feature

    1. Two-channel bidirectional buffer

    2. B-side integrated current source requires no external B-side resistor

    3. Ultra low power consumption

    4. No quiescent voltage offset, low VOL

    5. I2C bus and SMBus compatible

    6. Operating supply voltage range from 0.8 V to 3.6 V on the A side

    7. Operating supply voltage range from 1.65 V to 3.6 V on the B side

    8. Active high repeater enable input

    9. Power down the high impedance I2C bus pins on Aside

  10. Power-off backup power protection I2C bus pins

  11. Supports clock stretching and multi-master arbitration

  12. Family of current source options from 0.5 mA to 3 mA

3. Application

    1. Server

    2. Router (routing device)

    3. Industrial equipment

    4. personal computer

    5. Power-sensitive applications

4. Pin configuration

5. Pin Description

6. Function description

    1. Integrated current source

        The TCA9800DGKT series has an integrated current source on the B side. Using an integrated current source, the device is able to measure current to determine if an external device is pulling down the bus. This innovative detection method eliminates the need for a static voltage offset on the B side.

    2. Ultra low power consumption

        The TCA9800DGKT family features ultra-low power consumption to help maximize battery life or reduce power consumption in sensitive applications.

    3. No static voltage offset

        The TCA9800DGKT family has no quiescent voltage offset, which is typically used to buffer converters to prevent device lock-up situations where a low level on the output of the buffer itself could trigger the input low threshold. Eliminating the quiescent voltage offset is important because it allows the device to have a low VOL on the B side, which helps prevent communication problems caused by connecting a quiescent voltage offset output device to an input with an input low threshold below the quiescent voltage VOL.

    4. No static voltage offset

        The TCA9800DGKT family has no quiescent voltage offset, which is typically used to buffer converters to prevent device lock-up situations where a low level on the output of the buffer itself could trigger the input low threshold. Eliminating the quiescent voltage offset is important because it allows the device to have a low VOL on the B side, which helps prevent communication problems caused by connecting a quiescent voltage offset output device to an input with an input low threshold below the quiescent voltage VOL.

    5. Close the high impedance I2C bus pin on the A side

        When VCCA or VCCB is below its UVLO voltage, the SCLA and SDAA pins enter a high impedance state. These pins can safely continue to enable I2C communication, even when the device is disabled or without power. The SCLB and SDAB pins are still powered by their current sources (ICS) even if VCCA is lower than UVLO. When VCCB is lower than UVLO, the current source is turned off and a weak pull-up resistor is connected to prevent Bpin from floating. This is expected behavior as no external pull-up resistors are used on the SDAB or SCLB pins. This behavior prevents the bus pin from floating and allows it to follow VCCB.