Product details

Number of I/Os 8 Features Configuration registers, Interrupt pin Supply voltage (Min) (V) 2.3 Supply voltage (Max) (V) 5.5 Addresses 8 Rating Catalog Frequency (Max) (kHz) 400 Operating temperature range (C) -40 to 85
Number of I/Os 8 Features Configuration registers, Interrupt pin Supply voltage (Min) (V) 2.3 Supply voltage (Max) (V) 5.5 Addresses 8 Rating Catalog Frequency (Max) (kHz) 400 Operating temperature range (C) -40 to 85
SOIC (D) 16 59 mm² 9.9 x 6 SSOP (DB) 16 48 mm² 6.2 x 7.8 TSSOP (PW) 16 22 mm² 4.4 x 5 TVSOP (DGV) 16 23 mm² 3.6 x 6.4 VQFN (RGV) 16 16 mm² 4.0 x 4.0 VQFN (RGY) 16 14 mm² 4 x 3.5
  • Low Standby Current Consumption of 1 μA Max
  • I2C to Parallel Port Expander
  • Operating Power-Supply Voltage Range of 2.3 V to 5.5 V
  • 5-V Tolerant I/O Ports
  • 400-kHz Fast I2C Bus
  • Three Hardware Address Pins Allow for Use of up to Eight Devices on I2C/SMBus
  • Lower-Voltage Higher-Performance Migration Path for PCA9556
  • Input/Output Configuration Register
  • Polarity Inversion Register
  • Active-Low Reset Input
  • Internal Power-On Reset
  • High-Impedance Open Drain on P0
  • Power Up With All Channels Configured as Inputs
  • No Glitch on Power Up
  • Noise Filter on SCL/SDA Inputs
  • Latched Outputs With High Current Drive Maximum Capability for Directly Driving LEDs
  • Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
  • ESD Protection Exceeds JESD 22
    • 2000-V Human-Body Model (A114-A)
    • 200-V Machine Model (A115-A)
    • 1000-V Charged-Device Model (C101)

All trademarks are the property of their respective owners.

  • Low Standby Current Consumption of 1 μA Max
  • I2C to Parallel Port Expander
  • Operating Power-Supply Voltage Range of 2.3 V to 5.5 V
  • 5-V Tolerant I/O Ports
  • 400-kHz Fast I2C Bus
  • Three Hardware Address Pins Allow for Use of up to Eight Devices on I2C/SMBus
  • Lower-Voltage Higher-Performance Migration Path for PCA9556
  • Input/Output Configuration Register
  • Polarity Inversion Register
  • Active-Low Reset Input
  • Internal Power-On Reset
  • High-Impedance Open Drain on P0
  • Power Up With All Channels Configured as Inputs
  • No Glitch on Power Up
  • Noise Filter on SCL/SDA Inputs
  • Latched Outputs With High Current Drive Maximum Capability for Directly Driving LEDs
  • Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
  • ESD Protection Exceeds JESD 22
    • 2000-V Human-Body Model (A114-A)
    • 200-V Machine Model (A115-A)
    • 1000-V Charged-Device Model (C101)

All trademarks are the property of their respective owners.

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.

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.

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Technical documentation

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Type Title Date
* Data sheet PCA9557 Remote 8-Bit I2C and SMBus Low-Power I/O Expander datasheet (Rev. J) 12 Jun 2014
Application note I2C Dynamic Addressing 25 Apr 2019
Selection guide Logic Guide (Rev. AB) 12 Jun 2017
Application note Choosing the Correct I2C Device for New Designs 07 Sep 2016
Application note Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) 02 Dec 2015
Application note Understanding the I2C Bus 30 Jun 2015
Application note Maximum Clock Frequency of I2C Bus Using Repeaters 15 May 2015
Application note I2C Bus Pull-Up Resistor Calculation 13 Feb 2015
Application note Programming Fun Lights With TI's TCA6507 30 Nov 2007
Application note Semiconductor Packing Material Electrostatic Discharge (ESD) Protection 08 Jul 2004

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Package Pins Download
SOIC (D) 16 View options
SSOP (DB) 16 View options
TSSOP (PW) 16 View options
TVSOP (DGV) 16 View options
VQFN (RGV) 16 View options
VQFN (RGY) 16 View options

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