Allegro MicroSystems A8587KEJTR-T

Overview

A8587KEJTR-T from Allegro MicroSystems is a non-synchronous buck regulator with integrated 150 mΩ high-side MOSFET, supporting 3.8–36 V input and adjustable 0.8–30 V output at up to 2 A. It employs current-mode control, programmable switching frequency up to 4 MHz, and delivers fast transient response for automotive power rails and industrial DC-DC conversion.

For engineers reviewing the A8587KEJTR-T datasheet, A8587KEJTR-T pinout, A8587KEJTR-T application, or A8587KEJTR-T equivalent, key selection criteria include its AEC-Q100 qualification, 30 µA quiescent current in operation, NPOR active-low reset signal timing (7.5 ms typical delay), PFM light-load efficiency mode, and DFN10 thermal-pad package compatibility with high-density PCB layouts.

Technical Context

The A8587KEJTR-T uses current-mode PWM control with internal slope compensation (3.1 A/µs at 2 MHz) to support duty cycles >50% across wide VIN/VOUT ratios. Its transconductance error amplifier (60 µA/V typ.) interfaces with external RZ/CZ compensation and clamps COMP between 0.75 V and 1.5 V.

Startup sequencing includes pre-biased output handling, soft-start ramp (1.5 ms), and frequency foldback to prevent inductor current runaway. Protection architecture integrates pulse-by-pulse OCP (2.7 A typ.), hiccup-mode short-circuit response (6 ms off-time), BOOT open/short detection, and thermal shutdown at 170°C with 20°C hysteresis.

Key Specifications

Pinout & Package

Package: 10-pin DFN with exposed thermal pad (EJ suffix), 3 mm × 3 mm, 0.5 mm pitch, JEDEC-standard footprint optimized for thermal dissipation on 4-layer PCBs (R_θJA = 45 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM61480RQWR and MPQ4420AGL-A, the A8587KEJTR-T uniquely combines AEC-Q100 qualification, integrated NPOR with 7.5 ms delay, frequency dithering for CISPR-25 compliance, and BOOT/freewheel diode fault detection-making it the only option for safety-critical automotive subsystems requiring self-monitoring power delivery.

Availability

A8587KEJTR-T is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power rails, ADAS camera modules, and portable test equipment requiring stable component supply across extended temperature and lifecycle requirements.

Supply support for A8587KEJTR-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, magnetic sensors, and motor driver solutions for automotive and industrial markets.

The A8587 product line delivers high-voltage, high-efficiency DC-DC conversion for demanding environments-designed specifically for automotive power distribution, ADAS subsystems, and ruggedized industrial controls where reliability, EMI robustness, and functional safety are critical.

FAQ

What is the maximum input voltage rating for the A8587KEJTR-T?

The A8587KEJTR-T has an absolute maximum input voltage rating of 40 V, with recommended operating range from 3.8 V to 36 V. This allows direct connection to 24 V industrial buses and automotive batteries experiencing load dump transients up to 35 V. Operation above 36 V is not recommended for sustained use, as it exceeds the specified operating conditions and may impact long-term reliability.

Does the A8587KEJTR-T require an external freewheel diode, and what protection does it offer?

Yes, the A8587KEJTR-T requires an external freewheel diode connected between SW and GND. It includes dedicated open/short freewheeling diode protection: if the diode is open, the device detects SW node voltage below −1.25 V for >50 ns and enters hiccup mode; if shorted, excessive MOSFET current triggers immediate hiccup response. This prevents damage and enables field-repairable power stage design.

How is the switching frequency programmed on the A8587KEJTR-T?

The A8587KEJTR-T switching frequency is set by connecting a resistor (RFREQ) from the FREQ pin (Pin 7) to GND. For example, 45.3 kΩ yields 2.0 MHz (typ.), while 15.4 kΩ sets 4.0 MHz. The device incorporates ±8% frequency dithering at 12 kHz to reduce EMI peaks. Minimum controllable on-time (80 ns) limits usable duty cycle at frequencies >2 MHz, especially at high VIN/VOUT ratios.

What is the function and timing behavior of the NPOR pin on the A8587KEJTR-T?

The NPOR pin on the A8587KEJTR-T is an active-low open-drain power-on reset output that transitions high after VOUT reaches regulation (within ±3% of target). Its rising edge is delayed by 7.5 ms (typ.) to ensure stable output before releasing downstream logic reset. NPOR goes low if VFB falls below 730 mV or exceeds 880 mV, or during VIN UVLO or thermal shutdown-providing fault-aware system reset signaling.

Can the A8587KEJTR-T operate with a pre-biased output, and how does it handle startup?

Yes, the A8587KEJTR-T supports pre-biased startup. When VOUT is already present at power-on, the COMP pin remains low and SW is tri-stated until the internal soft-start voltage ramps above the sensed FB voltage. This prevents reverse current flow into the output capacitor and avoids discharging the pre-bias, enabling safe hot-swap and redundant power supply configurations without external isolation components.