描述 Description

The system master can reset the PCA9539 in the event of a time-out 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. Asserting RESET causes the same reset/initialization to occur without de-powering the part.

The PCA9539 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 master 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 PCA9539 can remain a simple slave device.

The device outputs (latched) have high-current drive capability for directly driving LEDs. The device has low current consumption.

The PCA9539 is identical to the PCA9555, except for the removal of the internal I/O pullup resistor, which greatly reduces power consumption when the I/Os are held low, replacement of A2 with RESET, and a different address range.

Two hardware pins (A0 and A1) are used to program and vary the fixed I2C address and allow up to four devices to share the same I2C bus or SMBus.

特性 Features

? 1μA 低待機(jī)電流消耗（最大值）
? I2C 至并行端口擴(kuò)展器
? 開(kāi)漏電路低電平有效中斷輸出
? 低電平有效復(fù)位輸入
? 可耐受 5V 電壓的 I/O 端口
? 兼容大多數(shù)微控制器
? 400kHz 快速 I2C 總線
? 極性反轉(zhuǎn)寄存器
? 通過(guò)兩個(gè)硬件地址引腳尋址，以便使用多達(dá) 4 個(gè)器件
? 具有高電流驅(qū)動(dòng)能力的鎖存輸出，用于直接驅(qū)動(dòng) LED
? 閂鎖性能超過(guò) 100mA，符合 JESD 78 II 類(lèi)規(guī)范的要求
? ESD 保護(hù)性能超過(guò) JESD 22 規(guī)范要求
? 2000V 人體放電模型 (A114-A)
? 1000V 帶電器件模型 (C101)