STMicroelectronics ST890BDR

Overview

ST890BDR from STMicroelectronics is a P-channel high-side power switch with programmable current limiting (up to 1.2 A), thermal shutdown, and active-low FAULT indicator output. It operates from 2.7 V to 5.5 V, features 90 mΩ typical ON resistance at 3 V, and is qualified for -40 °C to +85 °C industrial temperature range. Used in PCMCIA and access bus slots for load protection in portable 3 V/5 V systems.

For engineers reviewing the ST890BDR datasheet, ST890BDR pinout, ST890BDR application, or ST890BDR equivalent, key selection criteria include programmable ILIM via external resistor, open-drain FAULT signaling, thermal trip at 130 °C, and dual SO8/DFN8L 3x3 package availability for thermal and space-constrained designs.

Technical Context

The ST890BDR implements a P-MOSFET high-side switch with integrated current-sense amplifier, fast-response current-limit loop (5 µs typical), and thermal foldback. Its SET pin accepts a precision resistor to set ILIM between ~0.3 A and 1.2 A using ISET = 1110 µA and VSET = 1.24 V reference.

FAULT is an open-drain output asserted low during overcurrent (ILIM or short-circuit), undervoltage lockout (V_IN < 2.4 V), or thermal overload (>130 °C). The device includes 100 mV UVLO hysteresis and supports bypass capacitors on IN (1 µF) and OUT (0.1 µF) for stability.

Key Specifications

Pinout & Package

ST890BDR is available in SO8 (ECOPACK®) and DFN8L 3×3 mm packages. Both use identical pinout: dual IN pins (1,2), ON (3), GND (4), SET (5), dual OUT pins (6,7), and FAULT (8). The DFN8L's exposed pad is unconnected but recommended for PCB ground connection to improve thermal performance (R_thj-amb = 37.6 °C/W on 4-layer JEDEC board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side current-limited power switch applications.

Compared with TPS2051BDR and AP22653AW5-7, ST890BDR uniquely combines programmable current limit, thermal shutdown with hysteresis, and UVLO in a P-FET high-side switch - critical for robust portable and industrial load management where fault conditions must be actively managed, not just detected.

Availability

ST890BDR is available at Aetrix Electronics and suitable for PCMCIA slot control, access bus protection, and portable medical monitor power path applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ST890BDR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The ST890 product line delivers high-side power switches optimized for space-constrained, thermally demanding portable and industrial systems requiring programmable protection, low quiescent current, and robust fault signaling.

FAQ

What is the maximum continuous current the ST890BDR can safely switch?

The ST890BDR supports up to 1.2 A continuous output current when programmed via the SET pin and operated within its thermal limits. Absolute maximum continuous switching current is rated at 1.5 A, but sustained operation above 1.2 A risks triggering thermal shutdown due to power dissipation in the 90 mΩ R_ON. Derating is required above 70 °C ambient, especially in SO8 packages with higher R_thj-amb.

How do I calculate the R_SET value for a desired current limit?

Use the formula R_SET = 1110 µA / I_LIM, where I_LIM is your target current limit in amperes. For example, for 800 mA: R_SET = 0.00111 A / 0.8 A = 1.3875 kΩ - select 1.39 kΩ ±1% metal-film resistor. Ensure V_SET remains within 1.178–1.302 V per datasheet Table 7; verify with actual measurement under load.

Can the FAULT pin drive an LED directly without a microcontroller?

Yes - the FAULT pin is an open-drain output rated for 1 mA sink current. Connect an LED (e.g., 2 V forward voltage) in series with a current-limiting resistor (e.g., 3.3 kΩ for ~1 mA at 5.5 V) between V_CC and FAULT. The LED illuminates only during overcurrent, short-circuit, or thermal fault conditions, providing immediate visual status without firmware involvement.

Does the ST890BDR require external capacitors, and where should they be placed?

Yes - a 1 µF ceramic capacitor must be placed between IN and GND, and a 0.1 µF ceramic capacitor between OUT and GND. These minimize supply ripple and suppress switching transients that could cause false FAULT assertions or oscillation. Place both capacitors as close as possible to their respective pins, with short, low-inductance traces to GND.