Allegro MicroSystems A4407KLPTR-T

Overview

A4407KLPTR-T from Allegro MicroSystems is an AEC-Q100 Grade 0 automotive power management IC featuring a 2.2 MHz constant on-time buck pre-regulator (VREG output), two internal LDOs (5 V and 5 V tracking/protected), and two external N-channel FET controllers (for 3.3 V and 1.2/1.5/1.8 V rails). It delivers regulated power to CAN transceivers and microcontrollers in under-hood applications with input range 5.5–36 V, thermal shutdown at 170°C, and −40°C to 150°C junction operation.

For engineers reviewing the A4407KLPTR-T datasheet, A4407KLPTR-T pinout, A4407KLPTR-T application, or A4407KLPTR-T equivalent, key selection considerations include VIN dropout behavior at 5.5 V, programmable NPOR delay via CPOR capacitor, V5P short-to-battery protection, ENBAT ignition enable threshold (3.3 V typ), and TON resistor-based switching frequency tuning across input voltage range.

Technical Context

The A4407KLPTR-T implements valley-current-sensing constant on-time (COT) control for its buck pre-regulator, enabling stable 2.2 MHz operation across 8.6–31 V input while automatically extending period below 6.5 V (dropout mode) or above 31 V. Its dual enable architecture-logic-level ENB and high-voltage ENBAT-supports both microcontroller and ignition-switched startup, with OR logic enabling either path.

All four regulated outputs feature foldback overcurrent protection: V5 and V5P use internal current limiting with short-to-battery detection on V5P; 3.3 V and 1.2/1.5/1.8 V rails rely on external sense resistors (CL3V3/CL1V2) and gate drivers (G3V3/G1V2) for programmable current limits and foldback thresholds. NPOR monitors VREG, 3V3, and 1V2 UVLOs with adjustable delay and asserts low on any fault.

Key Specifications

Pinout & Package

Supplied in a 24-pin TSSOP package with exposed thermal pad (suffix LP), 1.1 mm profile, lead-free with 100% matte-tin plating. Thermal resistance R_θJA = 28°C/W on 4-layer JEDEC PCB.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive multi-rail power management applications.

Compared with MPQ4333-AEC1 and TPS65381A-Q1, the A4407KLPTR-T uniquely integrates a 2.2 MHz buck pre-regulator with V5P short-to-battery protection and dual external FET controllers - making it the only option supporting full CAN+MCU+peripheral power tree in high-temperature, wide-input automotive environments.

Availability

A4407KLPTR-T is available at Aetrix Electronics and suitable for electronic power steering (EPS), transmission control units (TCU), antilock braking systems (ABS), and emissions control modules requiring stable component supply across automotive production lifecycles.

Supply support for A4407KLPTR-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 designer of high-performance magnetic sensing and power ICs, specializing in automotive-grade solutions with AEC-Q100 qualification and robust thermal design.

The A4407 product line targets under-hood automotive power management, integrating buck pre-regulation with multiple protected LDOs and FET drivers to replace discrete power trees in EPS, TCU, and ABS modules.

FAQ

What is the minimum input voltage required for A4407KLPTR-T to regulate all outputs?

The A4407KLPTR-T maintains regulation down to 5.5 V input for all outputs. Below this, the buck enters 100% duty cycle dropout mode where VREG follows VIN minus R_DS(on) drop. V5, V5P, and 3V3 remain functional but with reduced current capability and higher dropout loss. This 5.5 V minimum supports automotive cold-crank conditions per ISO 16750-2.

How does the A4407KLPTR-T protect against short-to-battery faults on the V5P output?

The A4407KLPTR-T incorporates dedicated short-to-battery protection on the V5P pin. When V5P is shorted to battery voltage, internal circuitry limits current to −415 mA typical and activates foldback to −110 mA, preventing thermal runaway. Unlike standard overcurrent protection, this feature operates independently of load current direction and remains active even during ENBAT/ENB disable transitions.

Can the A4407KLPTR-T be used without an external asynchronous diode?

No - the A4407KLPTR-T requires an external asynchronous diode (e.g., B240A) between LX and GND. While it includes missing-diode detection (latching off if LX < −1.6 V for >157 ns), omission of the diode causes immediate latch-off during startup. The diode is essential for freewheeling current path and must be placed close to the LX pin to minimize parasitic inductance.

What determines the A4407KLPTR-T's switching frequency, and how is it adjusted?

The A4407KLPTR-T's switching frequency is set by the TON pin resistor value and input voltage. With R_TON = 412 kΩ, frequency is 2.2 MHz nominal between 8.6–31 V VIN; outside that range, period extends to maintain regulation. The on-time formula is t_ON = (R_TON/VIN) × 6.36×10⁻¹² + 5×10⁻⁹ seconds. No external clock or compensation components are needed.

How is the NPOR delay programmed on the A4407KLPTR-T, and what is its functional impact?

The NPOR delay on the A4407KLPTR-T is programmed by connecting a capacitor from CPOR to GND. Delay time is calculated as t_NPOR = 92.3×10³ × C_CPOR seconds (e.g., 0.22 µF yields ~20 ms). This delay ensures NPOR remains low until VREG, 3V3, and 1V2 all exceed their UVLO thresholds *and* the capacitor charges - guaranteeing stable power before releasing the microcontroller reset.