Allegro MicroSystems APEK81803KNB-5-T

Overview

APEK81803KNB-5-T from Allegro MicroSystems is a 40 V, 3 A synchronous buck regulator module in a 24-pin wettable flank QFN (4 mm × 4 mm × 2.1 mm), integrating high- and low-side MOSFETs, VIN and BOOT capacitors, and peak-current-mode control. It delivers ±1.5% output voltage accuracy from –40°C to 150°C, supports 0.8–24 V programmable VOUT, and achieves ultra-low 6 µA quiescent current in LP mode - ideal for automotive infotainment and ADAS power rails.

For engineers reviewing the APEK81803KNB-5-T datasheet, APEK81803KNB-5-T pinout, APEK81803KNB-5-T application, or APEK81803KNB-5-T equivalent, key selection criteria include its AEC-Q100 Grade 1 qualification, 250 kHz–2.4 MHz programmable switching frequency, integrated EMI-reduction features (spread spectrum, CLKOUT phase-shifted clock), and robust protection suite (hiccup OCP, BOOT fault detection, thermal shutdown).

Technical Context

The APEK81803KNB-5-T employs fixed-frequency peak-current-mode control with programmable oscillator (via FSET resistor or FREQ pin tie to VCC), enabling precise transient response and stable loop compensation. Its transconductance error amplifier features dual-input "analog OR" logic for seamless soft-start-to-regulation transition and supports adaptive gain scaling during startup.

It integrates two internal LDOs (VIN- and BIAS-fed) to supply VCC, enabling ultra-low IQ operation in LP mode while maintaining regulation across input voltages from 3.5 V to 36 V. Synchronization via PLL-based SYNCIN (400 kHz–2.4 MHz) and phase-shifted CLKOUT support multi-rail interleaving and system-level EMI reduction without external timing components.

Key Specifications

Pinout & Package

Package: 24-pin wettable flank QFN, 4 mm × 4 mm × 2.1 mm, with exposed VIN and PGND thermal pads for enhanced thermal dissipation and solder joint inspection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck regulator applications.

Compared with MPQ4433AGL-AEC1-P and TPS543B20RTWR, the APEK81803KNB-5-T provides superior EMI performance through integrated capacitors and spread spectrum, higher thermal resilience (150°C TJ), and complete AEC-Q100 Grade 1 compliance - making it the optimal choice for safety-critical automotive power rails where layout simplicity and regulatory compliance are non-negotiable.

Availability

APEK81803KNB-5-T is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera systems, and industrial telematics gateways requiring stable component supply, long lifecycle support, and AEC-Q100-compliant power delivery.

Supply support for APEK81803KNB-5-T 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

Allegro MicroSystems is a U.S.-based semiconductor company specializing in high-performance power ICs and magnetic sensing solutions for automotive and industrial markets.

The APEK81803KNB-5-T belongs to Allegro's ClearPower™ module family, engineered specifically for demanding automotive power conversion tasks - emphasizing ultra-low EMI, AEC-Q100 compliance, and minimal external component count.

FAQ

What is the maximum input voltage rating for the APEK81803KNB-5-T?

The APEK81803KNB-5-T has an absolute maximum input voltage rating of 40 V, with continuous operation supported from 3.5 V to 36 V. This allows reliable operation during automotive load-dump transients while maintaining regulation during cold-crank events down to 3.5 V input. The 40 V rating ensures margin against voltage spikes without requiring external clamping.

Does the APEK81803KNB-5-T support spread spectrum modulation?

Yes, the APEK81803KNB-5-T supports selectable spread spectrum dithering with ±5% to ±6.5% frequency deviation and 0.5% modulation frequency - a feature that significantly reduces peak radiated emissions. This capability is factory-enabled and contributes directly to CISPR25 Class 5 compliance without external components or layout changes.

How does the APEK81803KNB-5-T achieve 6 µA quiescent current?

The APEK81803KNB-5-T achieves 6 µA quiescent current by entering Low Power (LP) mode when the PWM/AUTO pin is pulled low. In this mode, it switches to hysteretic regulation, shuts down non-essential circuitry, and uses the BIAS pin (tied to VOUT) to power internal LDOs - eliminating current draw from VIN except for leakage paths. This behavior is validated across temperature and load conditions.

Is the APEK81803KNB-5-T pin-compatible with other variants in the APM81803 family?

Yes, the APEK81803KNB-5-T shares identical 24-pin wettable flank QFN packaging and pinout with all APM81803 variants (e.g., APM81803KNBJSR, APM81803KNBJSR-1). Differences are limited to dither enable/disable configuration and reel packaging - enabling drop-in replacement across production lots without PCB redesign.

What thermal performance can be expected from the APEK81803KNB-5-T on a standard PCB?

On a JEDEC-standard 4-layer PCB, the APEK81803KNB-5-T exhibits a thermal resistance of 42 °C/W (RθJA). With its exposed VIN and PGND thermal pads and wettable flank leads, it delivers robust thermal performance in automotive under-hood environments - sustaining full 3 A output current up to +105°C ambient when properly laid out per Allegro's guidelines.