NXP Semiconductors PCA9558PW,118

Overview

PCA9558PW,118 from NXP Semiconductors is an integrated I²C/SMBus device combining an 8-bit GPIO expander, a 5-bit multiplexed/1-bit latched 6-bit EEPROM DIP switch, and a 2-kbit serial EEPROM with write protection. It operates from 3.0 V to 3.6 V, supports up to 400 kHz bus speed, and features 5 V-tolerant open-drain outputs for board configuration, version tracking, and LED control in telecom line cards.

For engineers reviewing the PCA9558PW,118 datasheet, PCA9558PW,118 pinout, PCA9558PW,118 application, or PCA9558PW,118 equivalent, key selection criteria include its dual EEPROM architecture (6-bit + 2-kbit), active-low reset and override controls, SMBus compliance at 3.3 V, and TSSOP28 package compatibility with space-constrained server and networking PCBs.

Technical Context

The PCA9558PW,118 implements a hierarchical I²C interface with three distinct memory-mapped functional blocks: a 6-bit EEPROM for DIP-switch emulation (MUX_OUTx/NON_MUXED_OUT), a 256-byte (2-kbit) EEPROM for board ID/maintenance history, and eight configurable GPIO pins controlled via Input/Output Configuration (IOC), Output Port (OP), and Polarity Inversion (PI) registers. All are accessed using standardized command bytes per Table 3 of the datasheet.

Its multiplexer logic responds to both hardware pins (MUX_SELECT, MUX_OUT_LOW) and internal MUXCNTRL register bits, enabling dynamic switching between external MUX_INx inputs and EEPROM-stored values - with NON_MUXED_OUT latching on rising MUX_SELECT edge or I²C ACK depending on mode. The IO_OUT_LOW pin provides synchronous reset of all GPIO registers to power-up defaults.

Key Specifications

Pinout & Package

TSSOP28 (SOT361-1), 4.4 mm body width, 0.65 mm pitch - surface-mount package suitable for high-density telecom and server motherboard layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C I/O expander with integrated EEPROM applications.

Compared with PCA9557D,118 and PCA9555D,118, the PCA9558PW,118 uniquely integrates DIP-switch emulation, dual EEPROM, and GPIO in one TSSOP28 package - making it the only option for systems requiring hardware-selectable configuration with non-volatile retention and LED control in minimal footprint.

Availability

PCA9558PW,118 is available at Aetrix Electronics and suitable for telecom infrastructure, server motherboard design, and industrial embedded systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for PCA9558PW,118 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in I²C/SMBus interface IP and mixed-signal integration.

The PCA9558PW,118 belongs to NXP's I²C peripheral portfolio designed specifically for board-level configuration, identification, and health monitoring in high-reliability computing and communications equipment.

FAQ

What is the primary function of the PCA9558PW,118 in a server motherboard?

The PCA9558PW,118 serves as a consolidated configuration and monitoring hub on server motherboards. It stores board revision data in its 2-kbit EEPROM, selects processor voltage IDs via its 5-bit multiplexer, and drives status LEDs using its 8-bit GPIO - reducing discrete components while enabling field-upgradable settings without physical access.

Does the PCA9558PW,118 support 5 V I²C bus operation?

No, the PCA9558PW,118 requires a 3.0 V to 3.6 V supply (VDD) and is not rated for 5 V operation. However, its SCL, SDA, and all GPIO/MUX pins are 5 V tolerant, allowing safe connection to 5 V I²C masters when pulled to 3.3 V logic levels via appropriate resistors.

How does the MUX_SELECT pin affect the NON_MUXED_OUT output on the PCA9558PW,118?

When MUX_SELECT is LOW, NON_MUXED_OUT reflects the latched value from the 6-bit EEPROM. On the rising edge of MUX_SELECT, that EEPROM value is captured and held - making NON_MUXED_OUT transparent to EEPROM changes until the next rising edge. This enables precise timing of configuration updates independent of bus traffic.

Can the PCA9558PW,118 be used to replace mechanical DIP switches in telecom line cards?

Yes, the PCA9558PW,118 is explicitly designed for DIP switch replacement. Its 5-bit multiplexer reads hardware inputs (MUX_INA–E) or EEPROM-stored values and drives MUX_OUTx outputs accordingly - allowing configuration changes via I²C without powering down equipment or opening chassis.

What happens to the GPIO registers when the IO_OUT_LOW pin is asserted on the PCA9558PW,118?

Asserting IO_OUT_LOW (driving it LOW for ≥ Tcy(W)) resets the PCA9558PW,118's Output Port (OP), Polarity Inversion (PI), and Input/Output Configuration (IOC) registers to their power-up default states - restoring all IO0–IO7 to output mode with logic 0 output, regardless of prior software configuration.