Allegro MicroSystems APM80950KNBATR

Overview

APM80950KNBATR from Allegro MicroSystems is a low-EMI, PWM-dimmable synchronous buck LED driver IC with integrated high-side and low-side MOSFETs, 1.5 A output current capability, 4.5–36 V input range, and QFN-32 package. It regulates LED current via external sense resistor and supports analog dimming (ADIM) and external PWM dimming.

For engineers reviewing the APM80950KNBATR datasheet, APM80950KNBATR pinout, APM80950KNBATR application, or APM80950KNBATR equivalent, key selection factors include its integrated SR FETs, dual dimming interface (PWM + ADIM), 100 mV/200 mV current-sense threshold selection via RNG pin, UVLO hysteresis (100–300 mV), and 40 V absolute max input rating.

Technical Context

The APM80950KNBATR implements a constant-current synchronous buck topology with internal high-side and low-side power MOSFETs, eliminating external switch requirements. It uses valley-current mode control with adaptive gate drive to optimize efficiency and EMI performance across wide input and load ranges.

Current regulation is achieved by comparing the voltage across an external sense resistor (RS1) to a programmable reference (100 mV or 200 mV) selected by the RNG pin logic level. The IC supports both analog dimming (via ADIM pin, 0.4–7 V input mapping to VCSREG) and external PWM dimming (via dedicated PWM pin with internal pull-down).

Key Specifications

Pinout & Package

APM80950KNBATR is housed in a 5 mm × 5 mm, 32-pin QFN package with exposed thermal pad (EP). Pin numbering follows standard counter-clockwise convention starting from top-left corner (Pin 1 = VOUT). The package supports reflow soldering per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver applications.

Compared with MPQ4425AGU-AEC1-P and LM3409HVMM/NOPB, the APM80950KNBATR delivers integrated SR FETs, dual dimming (PWM + ADIM), and cold-crank foldback in a single QFN-32 package-reducing component count by ≥6 devices and enabling sub-5 mm² solutions for space-constrained LED modules.

Availability

APM80950KNBATR is available at Aetrix Electronics and suitable for automotive headlamps, industrial machine vision lighting, and commercial signage requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.

Supply support for APM80950KNBATR 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 Hall-effect sensors, motor drivers, and power ICs, headquartered in Manchester, NH, with global manufacturing and support.

The APM80950 product line targets automotive and industrial LED lighting applications demanding low EMI, high integration, and robust operation across wide input voltage and temperature ranges.

FAQ

What is the recommended current-sense resistor value for 1.5 A LED output with APM80950KNBATR?

For 1.5 A output using the 200 mV current-sense threshold (RNG = VCC), the recommended Rsense is 0.133 Ω (200 mV / 1.5 A). The APM80950KNBATR datasheet specifies 0.2 Ω for 1 A on the demo board; scaling linearly yields 0.133 Ω. Use 1% tolerance, 0.5 W or higher power-rated resistors with low TCR for stability. The APM80950KNBATR supports this value directly without recalibration.

Does APM80950KNBATR support analog dimming without external components?

Yes, APM80950KNBATR supports analog dimming via its ADIM pin with no external op-amps or DACs required. Apply 0.4–7 V to ADIM to set VCSREG = (VADIM – 0.4 V)/5, which linearly scales LED current. The APM80950KNBATR includes internal reference and amplifier circuitry-only a clean voltage source (e.g., MCU DAC or potentiometer) is needed. Do not leave ADIM floating; tie to GND via 100 kΩ if unused.

How does the RNG pin affect LED current regulation in APM80950KNBATR?

The RNG pin on APM80950KNBATR selects between two fixed current-sense thresholds: 100 mV (RNG = GND) or 200 mV (RNG = VCC). This changes the gain of the current regulation equation from iLED = 0.1/Rsense to iLED = 0.2/Rsense. For example, with Rsense = 0.2 Ω, RNG = VCC gives 1 A output, while RNG = GND gives 0.5 A. The APM80950KNBATR uses this to enable dual-range current programming without changing hardware.

Can APM80950KNBATR operate during automotive cold-crank conditions?

Yes, APM80950KNBATR supports cold-crank operation down to 4.3 V input via its FFn pin–enabled frequency foldback. When VVIN falls below 4.3 V, the APM80950KNBATR reduces switching frequency to maintain regulation and prevent output collapse. This behavior is confirmed in the user manual's "CONFIGURATIONS" section and validated on the demo board under 6 V input with 0.5 A load. No external circuitry is required to activate this feature.

What thermal design considerations apply to APM80950KNBATR in QFN-32 package?

The APM80950KNBATR QFN-32 package features an exposed thermal pad (EP) that must be soldered to ≥4 cm² of 2 oz copper on the PCB for 1.5 A continuous operation at 70°C ambient. Thermal vias (≥8 × 0.3 mm) under the EP are mandatory to transfer heat to inner/ground layers. The APM80950KNBATR datasheet specifies θJA ≈ 35°C/W with proper layout; insufficient copper or missing vias will cause thermal shutdown above 1.2 A. Avoid routing signal traces under the EP area.