PCA9557PW

远程8位I2C和SMBus低功耗I / O扩展器，带有复位和配置寄存器 REMOTE 8-BIT I2C AND SMBus LOW-POWER I/O EXPANDER WITH RESET AND CONFIGURATION REGISTERS

This 8-bit I/O expander for the two-line bidirectional bus I2C is designed for 2.3-V to 5.5-V VCC operation. The device provides general-purpose remote I/O expansion for most microcontroller families via the I2C interface [serial clock SCL and serial data SDA].

The PCA9557 consists of one 8-bit configuration input or output selection, input port, output port, and polarity inversion active-high registers. At power on, the I/Os are configured as inputs. However, the system master 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 master.

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

The system master can reset the PCA9557 in the event of a timeout or other improper operation by asserting a low in the active-low reset 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 depowering the part.

Three hardware pins A0, A1, and A2 are used to program and vary the fixed I2C address, allowing up to eight devices to share the same I2C bus or SMBus.