Texas Instruments TPS2231PWR

Overview

TPS2231PWR from Texas Instruments is a single-slot ExpressCard™ power interface switch IC that distributes and regulates 3.3 V, 1.5 V, and AUX power rails to ExpressCard|34/|54 sockets with integrated current limiting, thermal protection, and precise voltage sequencing. It supports notebook and desktop host systems requiring compliant hot-plug power management for PCI Express or USB-based expansion cards.

For engineers reviewing the TPS2231PWR datasheet, TPS2231PWR pinout, TPS2231PWR application, or TPS2231PWR equivalent, key selection criteria include its 24-pin PowerPAD™ HTSSOP package, dual-rail current-limiting (1.3 A @ 3.3VOUT, 650 mA @ 1.5VOUT), PERST/RCLKEN timing coordination, UVLO thresholds (2.6 V on 3.3VIN), and ExpressCard™ compliance verification.

Technical Context

The TPS2231PWR implements three independent MOSFET power switches - one per rail (3.3VOUT, 1.5VOUT, AUXOUT) - each with internal current-sense circuitry, thermal shutdown (trip at 155–165°C), and discharge FETs for safe card removal. Its control logic interprets CPPE/CPUSB, SHDN, STBY, and SYSRST to enforce ExpressCard™ power-state transitions including No Card, Card Inserted, Standby, and Shutdown modes.

It features tightly coupled timing functions: RCLKEN release triggers a programmable PERST de-assertion delay (4–20 ms), while PERST assertion occurs within 500 ns of any output falling out of tolerance. All outputs are protected by undervoltage lockout (UVLO) with hysteresis (100 mV) and short-circuit response (<150 µs).

Key Specifications

Pinout & Package

TPS2231PWR is housed in a 24-pin PowerPAD™ HTSSOP (PWP) package with exposed thermal pad for enhanced heat dissipation. The PowerPAD must be soldered to PCB ground plane to achieve rated 3153 mW power dissipation at TA = 25°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ExpressCard power management applications.

Compared with TPS2231PW and TPS2236DAP, the TPS2231PWR uniquely balances single-slot ExpressCard functionality with industry-leading thermal capability via its 24-pin PowerPAD™ HTSSOP package - making it optimal for thermally dense notebook designs where reliability under sustained 1.3 A 3.3VOUT load is critical.

Availability

TPS2231PWR is available at Aetrix Electronics and suitable for notebook computers, desktop computers, personal digital assistants (PDAs), and digital cameras requiring stable component supply, ExpressCard™ compliance, and robust hot-plug power management.

Supply support for TPS2231PWR 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 leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in power management and interface solutions.

The TPS2231PWR belongs to TI's ExpressCard™ power interface switch product line, engineered specifically to simplify host-side compliance with PCI-SIG and PCMCIA ExpressCard™ mechanical, electrical, and timing specifications.

FAQ

What is the primary function of the TPS2231PWR in an ExpressCard host system?

The TPS2231PWR serves as the dedicated power interface switch for single-slot ExpressCard|34 or ExpressCard|54 host systems. It manages the distribution, sequencing, and protection of three critical voltage rails - 3.3VOUT, 1.5VOUT, and AUXOUT - while enforcing ExpressCard™-specified timing relationships between RCLKEN, PERST, and card-insertion detection signals (CPPE/CPUSB). Its integrated current limiting, thermal shutdown, and discharge FETs eliminate the need for external protection circuitry in the TPS2231PWR design.

How does the TPS2231PWR handle card removal to prevent backfeeding or ESD damage?

The TPS2231PWR automatically activates internal discharge FETs on all three output rails (3.3VOUT, 1.5VOUT, AUXOUT) whenever CPPE and CPUSB both go high - indicating card removal. This safely pulls each output to GND within milliseconds, preventing backfeeding into the host power domain and suppressing voltage transients that could cause ESD stress on the ExpressCard connector or downstream circuitry. The discharge action is break-before-make, ensuring no shoot-through during transition, and is fully hardware-controlled without firmware intervention in the TPS2231PWR.

What are the UVLO thresholds for the TPS2231PWR inputs, and why are they important?

TPS2231PWR features three independent undervoltage lockout (UVLO) comparators: 3.3VIN UVLO trips at 2.6–2.9 V, 1.5VIN UVLO at 1.0–1.25 V, and AUXIN UVLO at 2.6–2.9 V, each with 100 mV hysteresis. These thresholds ensure that power switches remain disabled until input supplies are stable and within specification - preventing erratic behavior, incomplete power-up sequences, or partial rail activation that could corrupt ExpressCard enumeration. The tight tolerances and hysteresis guarantee reliable startup across temperature and supply variance in the TPS2231PWR.

Can the TPS2231PWR be used in dual-slot ExpressCard systems?

No, the TPS2231PWR is designed exclusively for single-slot ExpressCard|34 or ExpressCard|54 host implementations. Dual-slot systems require the TPS2236DAP, which integrates two independent power switch channels with separate PERST, RCLKEN, OC, and card-detection logic per slot. Attempting to use the TPS2231PWR in a dual-slot configuration would violate ExpressCard™ timing requirements, compromise fault isolation, and lack necessary signaling for slot arbitration - making the TPS2231PWR unsuitable for such applications.

What is the role of the RCLKEN pin on the TPS2231PWR, and how does it interact with PERST?

RCLKEN on the TPS2231PWR is a bidirectional open-drain pin that acts as both a status indicator and a timing control input. As an output, it releases high (after internal discharge FET turns off) once all three output rails (3.3VOUT, 1.5VOUT, AUXOUT) are within tolerance - signaling "power good." This RCLKEN transition triggers an internal timer that delays PERST de-assertion by 4–20 ms, satisfying ExpressCard™ requirements for stable power before reset release. As an input, holding RCLKEN low externally prevents the timer from starting, allowing the host to precisely control PERST timing - a critical function implemented directly in the TPS2231PWR silicon.