NXP Semiconductors PCA9561D,112

Overview

PCA9561D,112 from NXP Semiconductors is a 20-pin TSSOP I²C-bus EEPROM DIP switch IC used for jumperless CPU VID configuration between processor and VRM. It integrates four 6-bit non-volatile EEPROM registers, six hardware input pins (MUX_IN_A–F), and six open-drain multiplexed outputs (MUX_OUT_A–F), supporting dynamic voltage tuning across five independent settings (four EEPROM + one hardware) in mobile/desktop SpeedStep and server applications.

For engineers reviewing the PCA9561D,112 datasheet, PCA9561D,112 pinout, PCA9561D,112 application, or PCA9561D,112 equivalent, this device enables precise, field-updatable CPU voltage selection without power-down-critical for performance boosting (up to 7.5% frequency gain), battery conservation, and DIP-switch replacement in telecom/networking infrastructure.

Technical Context

The PCA9561D,112 implements a dual-source 6-bit multiplexer controlled by MUX_SELECT: when low, outputs reflect EEPROM register 0–3 contents selected via I²C; when high, outputs mirror MUX_IN_A–F inputs directly. Its I²C interface supports up to 400 kHz Fast-mode operation, with address pins A0/A1 enabling four devices on one bus.

Non-volatile storage uses EEPROM cells rated for ≥100,000 write cycles and 10-year data retention. Write protection is managed by the WP pin, and internal Power-On Reset ensures deterministic initialization at VDD ≥ 2.3 V. All I/O pins are 5 V tolerant with hysteresis and spike suppression per JESD22-A114/C101.

Key Specifications

Pinout & Package

TSSOP20 package (SOT360-1), 4.4 mm body width, 0.65 mm pitch, 1.1 mm max height - optimized for high-density PCB layouts in laptops and servers.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar VID configuration applications.

Compared with PCA9559PW,118 and PCA9560PW,118, the PCA9561D,112 uniquely delivers five independent VID sources (4 EEPROM + 1 hardware), I²C-override capability, and dedicated write protection-making it the only option for robust, field-updatable, multi-mode CPU voltage control in production systems.

Availability

PCA9561D,112 is available at Aetrix Electronics and suitable for laptop SpeedStep implementation, server BMC-integrated VID tuning, and telecom baseband processor configuration requiring stable component supply and long-term obsolescence management.

Supply support for PCA9561D,112 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 interface and power management ICs.

The PCA9561D,112 belongs to NXP's I²C EEPROM DIP switch product line, designed specifically to replace mechanical configuration elements in high-reliability computing platforms where remote, non-invasive voltage tuning is essential.

FAQ

What is the primary function of the PCA9561D,112 in a CPU voltage regulation system?

The PCA9561D,112 serves as a programmable VID translator between the CPU and Voltage Regulator Module (VRM). It selects from five independent voltage identification codes-four stored in non-volatile EEPROM registers and one derived from hardware inputs-and drives them onto six open-drain MUX_OUT pins. This enables dynamic, software-controlled CPU voltage adjustment without physical jumpers, supporting performance boosts up to 7.5% or battery-saving sleep modes. The PCA9561D,112 is explicitly designed for this role in mobile, desktop, and server platforms.

How does the MUX_SELECT pin interact with I²C-bus control in the PCA9561D,112?

The MUX_SELECT pin determines the source of the MUX_OUT signals: when low, outputs reflect the EEPROM register selected via I²C command byte; when high, outputs mirror the MUX_IN_A–F hardware inputs. Crucially, the I²C interface can override MUX_SELECT-writing a valid EEPROM address forces EEPROM output regardless of MUX_SELECT logic level. This dual-control mechanism ensures both hardware fail-safe and software flexibility. The PCA9561D,112 datasheet confirms this behavior in Table 5 and Section 6.3.

What are the voltage tolerance and supply requirements for the PCA9561D,112?

The PCA9561D,112 operates from a 3.0 V to 3.6 V VDD supply, with Power-On Reset activating above 2.3 V. All digital I/O pins-including SCL, SDA, A0, A1, MUX_IN_X, MUX_SELECT, and MUX_OUT_X-are 5 V and 2.5 V tolerant, meaning they safely accept input voltages up to 5.5 V (or VDD + 4.0 V, whichever is lower). This tolerance eliminates external level shifters when interfacing with mixed-voltage systems. These specifications are confirmed in Tables 10, 13, and 15 of the PCA9561D,112 datasheet.

Can the PCA9561D,112 be used in systems requiring frequent VID updates during operation?

Yes-the PCA9561D,112 supports field-updatable VID settings via its I²C interface without requiring power cycling. Each EEPROM write completes in ≤3.6 ms, after which the device resumes normal addressing. With ≥100,000 guaranteed write cycles and 10-year data retention, it withstands repeated reconfiguration during system validation, thermal tuning, or firmware updates. The WP pin provides hardware-level write protection to prevent accidental changes. This capability is central to the PCA9561D,112's design for SpeedStep and server BMC applications.

What package and pin count does the PCA9561D,112 use, and how is it mounted?

The PCA9561D,112 is supplied in a TSSOP20 package (SOT360-1): 20-pin, plastic thin shrink small outline, 4.4 mm body width, 0.65 mm lead pitch. It is a surface-mount device intended for reflow soldering per JEDEC J-STD-020 guidelines. The package outline and soldering recommendations-including moisture sensitivity level and peak temperature limits-are detailed in Sections 15 and 16 of the PCA9561D,112 datasheet. No through-hole or socket variants exist for this part number.