この 2 線式双方向バス (I2C) 用 24 ビット I/O エクスパンダは、I2C インターフェイス [シリアル・クロック (SCL) とシリアル・データ (SDA )] を介して、ほとんどのマイクロコントローラ・ファミリの汎用リモート I/O 拡張を実現できるように設計されています。
このデバイスの主な利点は、VCC 範囲が広いことです。P ポート側と SDA/SCL 側で、1.65V~5.5V で動作可能です。このため、TCA6424A は SDA/SCL 側で、消費電力削減のため電源電圧レベルが引き下げられる次世代のマイクロプロセッサおよびマイクロコントローラと接続できます。マイクロプロセッサの電源供給は低下しますが、LED など PCB の部品には引き続き 5V の電源を供給します。
型番 | パッケージ (1) | 本体サイズ |
---|---|---|
TCA6424A | UQFN (32) | 5.00mm × 5.00mm |
Changes from Revision C (April 2014) to Revision D (January 2023)
Changes from Revision B (September 2010) to Revision C (April 2014)
Changes from Revision A (August 2010) to Revision B (September 2010)
Changes from Revision * (July 2010) to Revision A (August 2010)
The bidirectional voltage level translation in the TCA6424A is provided through VCCI. VCCI should be connected to the VCC of the external SCL/SDA lines. This indicates the VCC level of the I2C bus to the TCA6424A. The voltage level on the P-port of the TCA6424A is determined by the VCCP.
The TCA6424A consists of three 8-bit Configuration (input or output selection), Input, Output, and Polarity Inversion (active high) registers. At power on, the I/Os are configured as inputs. However, the system controller can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding input or output register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. All registers can be read by the system controller.
The system controller can reset the TCA6424A in the event of a timeout or other improper operation by asserting a low in the RESET input. The power-on reset puts the registers in their default state and initializes the I2C/SMBus state machine. The RESET pin causes the same reset/initialization to occur without depowering the part.
The TCA6424A open-drain interrupt ( INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system controller that an input state has changed.
INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the I2C bus. Thus, the TCA6424A can remain a simple target device.
The device P-port outputs have high-current sink capabilities for directly driving LEDs while consuming low device current.
One hardware pin (ADDR) can be used to program and vary the fixed I2C address and allow up to two devices to share the same I2C bus or SMBus.