Texas Instruments TPS2231PWP

Overview

TPS2231PWP 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 power-good signaling. It supports notebook computers and desktop systems requiring compliant hot-plug power management for PCI Express and USB-based add-in cards.

For engineers reviewing the TPS2231PWP datasheet, TPS2231PWP pinout, TPS2231PWP application, or TPS2231PWP equivalent, key selection criteria include its 24-pin PowerPAD™ HTSSOP package, dual-rail current limits (1.3 A @ 3.3VOUT, 650 mA @ 1.5VOUT), 120 mΩ AUXOUT switch resistance, –40°C to 85°C operating range, and ExpressCard™ compliance per implementation guidelines.

Technical Context

The TPS2231PWP implements three independent MOSFET power switches-3.3VIN→3.3VOUT, 1.5VIN→1.5VOUT, and AUXIN→AUXOUT-with per-rail overcurrent detection, thermal shutdown at 165°C, and undervoltage lockout (UVLO) thresholds of 2.6 V on 3.3VIN/AUXIN and 1.0 V on 1.5VIN. Its control logic interprets CPPE/CPUSB card-present signals to enable rail sequencing and manages PERST assertion timing relative to RCLKEN release.

It integrates discharge FETs on all outputs activated during shutdown, no-card, or UVLO conditions; supports TTL-compatible logic inputs (SHDN, STBY, SYSRST); and delivers precise power-good status via open-drain OC and PERST outputs with defined rise/fall times (0.1–6 ms) and delay tolerances (500 ns to 20 ms).

Key Specifications

Pinout & Package

TPS2231PWP uses a 24-pin PowerPAD™ HTSSOP (PWP) package with exposed thermal pad on underside. Pin 1 is top-left corner (marking dot adjacent), pin count increases left-to-right, top row then bottom row.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS2231PW, the TPS2231PWP delivers 4.5× higher thermal power handling for sustained 1.3-A loads; compared with TPS2236DAP, it provides single-slot functionality in a smaller 24-pin footprint with identical control logic but no dual-channel capability.

Availability

TPS2231PWP is available at Aetrix Electronics and suitable for notebook computers, desktop computers, and digital cameras requiring stable component supply with guaranteed ExpressCard™ compliance and industrial temperature operation.

Supply support for TPS2231PWP 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 over 50 years of innovation in power management ICs.

The TPS2231PWP belongs to TI's ExpressCard™ power interface switch product line, designed specifically to simplify host-side compliance with PCI-SIG and USB-IF ExpressCard mechanical and electrical specifications.

FAQ

What is the primary function of the TPS2231PWP in an ExpressCard system?

The TPS2231PWP serves as the host-side power interface switch that manages delivery of 3.3 V, 1.5 V, and AUX power rails to an ExpressCard|34 or ExpressCard|54 socket. It integrates current limiting, thermal protection, card-present detection (via CPPE/CPUSB), and precise power-good signaling (PERST, RCLKEN) to ensure full compliance with the ExpressCard™ standard. The TPS2231PWP replaces discrete FETs, sense resistors, and timing circuits typically required for this function.

How does the TPS2231PWP handle overcurrent conditions on its output rails?

The TPS2231PWP monitors each output rail (3.3VOUT, 1.5VOUT, AUXOUT) with dedicated current-sense circuitry. When an overcurrent event occurs, the affected rail is immediately current-limited, and the open-drain OC pin is asserted low after a 6–20 ms deglitch period. The device continues regulating within its current limit (1.3 A for 3.3VOUT, 650 mA for 1.5VOUT, 275 mA for AUXOUT) and does not latch off unless thermal shutdown is triggered. The TPS2231PWP maintains operation of unaffected rails during the event.

What is the role of the RCLKEN pin on the TPS2231PWP, and how is it used in system design?

RCLKEN on the TPS2231PWP is a bidirectional pin serving as both an output (power-good indicator) and input (timing control). As an output, it transitions high after all voltage rails stabilize, initiating the PERST de-assertion timer. As an input, it can be driven low by the host to delay PERST de-assertion - enabling synchronization with reference clock enable sequences. The TPS2231PWP requires RCLKEN to be pulled up to AUXIN internally; external drivers must only sink current, never source it.

Does the TPS2231PWP support both PCI Express and USB-based ExpressCards?

Yes, the TPS2231PWP explicitly supports both interfaces through dedicated CPPE (Card Present for PCI Express) and CPUSB (Card Present for USB) inputs. These pins are internally pulled up to AUXIN and go low when the corresponding ExpressCard type is inserted and grounded. The TPS2231PWP uses these signals to determine card type and enable appropriate power rails - ensuring correct 3.3V/1.5V/AUX delivery whether the module is PCIe or USB-based. This dual-support is verified in TI's SLVS536A datasheet.

What thermal performance advantages does the PWP package offer over the PW package for the TPS2231PWP?

The TPS2231PWP's 24-pin PowerPAD™ HTSSOP (PWP) package provides significantly higher thermal performance than the 20-pin TSSOP (PW) variant: 3153 mW maximum power dissipation at 25°C versus 704 mW, with a derating factor of 33.19 mW/°C versus 7.41 mW/°C. This 4.5× improvement enables sustained 1.3-A operation on 3.3VOUT without thermal throttling in compact, high-density layouts - critical for thin-and-light notebooks where airflow is limited. The thermal pad must be soldered to PCB copper for rated performance.