Texas Instruments PCA8550PWR

Overview

PCA8550PWR from Texas Instruments is a nonvolatile 5-bit register IC with I²C interface, designed for jumperless configuration of PC motherboards. It integrates a 4-bit 1-of-2 multiplexer and latched non-muxed output, operates from 3 V to 3.6 V, supports fast-mode (400 kbit/s) I²C, and provides 2.5-V MUX OUT and 3.3-V NON-MUXED OUT signals.

For engineers reviewing the PCA8550PWR datasheet, PCA8550PWR pinout, PCA8550PWR application, or PCA8550PWR equivalent, this device serves as a configuration register with write protection, override control, and 10-year data retention-critical for BIOS/UEFI setup, hardware strapping, and embedded system initialization where persistent state must survive power cycles.

Technical Context

The PCA8550PWR implements an I²C slave interface with fixed 7-bit address 1001110 (0x4E), supporting standard- and fast-mode timing. Its internal architecture includes a 5-bit nonvolatile EPROM register (4 bits for MUX outputs + 1 latched bit), a transparent latch for the NON-MUXED OUT, and Schmitt-trigger SCL/SDA inputs with integrated pullups and 5-V tolerance.

Functionally, it decodes MUX SELECT to route one of four parallel MUX IN signals to corresponding MUX OUT pins while holding the NON-MUXED OUT at its latched value during writes. The OVERRIDE input forces all outputs low, and WP enables/disables register writes based on its logic level during the falling edge of the first valid data byte acknowledge.

Key Specifications

Pinout & Package

PW package: Thin Shrink Small-Outline (TSSOP), 16-pin, 0.65-mm pitch, body size 5 mm × 4.4 mm, exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nonvolatile I²C configuration register applications.

Compared with PCA9555PW and AT24C02C-SSHM-T, the PCA8550PWR uniquely integrates nonvolatile storage, multiplexer routing, and output latching in a single 16-pin TSSOP-reducing component count and eliminating firmware dependency for basic hardware strapping tasks.

Availability

PCA8550PWR is available at Aetrix Electronics and suitable for PC motherboard design, server baseboard management, and industrial embedded configuration requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for PCA8550PWR 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The PCA8550PWR belongs to TI's legacy interface and configuration IC portfolio, designed specifically for jumperless hardware setup in computing platforms where reliable, low-pin-count nonvolatile control is essential.

FAQ

What is the I²C address of the PCA8550PWR?

The PCA8550PWR uses a fixed 7-bit I²C slave address of 1001110 (0x4E). This address is hardwired and not configurable. The R/W bit follows in the 8-bit address byte, making the full write address 0x9C and read address 0x9D. No external address pins or jumpers affect this value, ensuring consistent bus enumeration in multi-device systems.

Does the PCA8550PWR require external pull-up resistors on SCL and SDA?

No, the PCA8550PWR includes integrated pull-up resistors on both SCL and SDA pins. These internal pullups eliminate the need for external resistors in standard I²C implementations, simplifying board layout and reducing BOM count. However, system-level bus capacitance and speed requirements may still necessitate supplemental pullups for robust 400 kbit/s operation across longer traces or multi-drop configurations.

How does the OVERRIDE function interact with the latched NON-MUXED OUT in the PCA8550PWR?

The OVERRIDE input forces all outputs-including MUX OUT A–D and NON-MUXED OUT-to logic low, overriding both register contents and the latched state. When OVERRIDE is deasserted, NON-MUXED OUT resumes its previously latched value (not the current register bit), preserving the state captured at the last MUX SELECT rising edge. This behavior ensures predictable recovery after fault conditions without requiring register re-read.

Can the PCA8550PWR operate with a 5-V VCC supply?

No, the PCA8550PWR is specified for VCC = 3 V to 3.6 V only. While its SCL and SDA inputs tolerate up to 5.5 V, applying 5 V to VCC exceeds absolute maximum ratings and risks permanent damage. Operation outside the recommended 3.3-V range invalidates all electrical specifications-including output voltage levels, timing, and nonvolatile write reliability-so 5-V VCC must be avoided.

What happens to the PCA8550PWR outputs during a write cycle?

During an I²C write cycle, the PCA8550PWR holds MUX OUT A–D and NON-MUXED OUT at their pre-write states until the stop condition completes and the internal write pulse is triggered (if WP is low). The NON-MUXED OUT remains latched, and MUX OUTs retain prior values-no glitching or intermediate states occur. This ensures stable hardware configuration throughout the 10-ms EEPROM write time, critical for systems that must maintain functional outputs during updates.