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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > LED Drivers

Allegro MicroSystems A6271KLPTR-T-1

Name: A6271KLPTR-T-1
Brand: Allegro MicroSystems
SKU: A6271KLPTR-T-1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A6271KLPTR-T-1

Manufacturer:: Allegro MicroSystems

Category:: LED Drivers

Package:: 16-TSSOP (0.173", 4.40mm Width) Exposed Pad

Datasheet:: A6271KLPTR-T-1.pdf

Description:: IC LED DRIVER CTRLR PWM 16ETSSOP

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Product details

Overview

A6271KLPTR-T-1 from Allegro MicroSystems is an automotive-grade DC-DC LED controller IC implementing peak current-mode control to drive high-power LED strings in boost, buck-boost, buck, or SEPIC topologies. It delivers programmable constant-current output up to 53.3 V string voltage, supports 4.2–50 V input, and features integrated PWMOUT for external p-channel MOSFET dimming. It is used in automotive headlight and DRL systems requiring AEC-Q100-compliant, fault-protected LED drive.

For engineers reviewing the A6271KLPTR-T-1 datasheet, A6271KLPTR-T-1 pinout, A6271KLPTR-T-1 application, or A6271KLPTR-T-1 equivalent, key selection criteria include its 70–700 kHz programmable switching frequency, dual analog/PWM dimming capability, fixed + programmable overvoltage protection, thermal shutdown at 155 °C, and eTSSOP-16 package with exposed thermal pad for automotive thermal management.

Technical Context

The A6271KLPTR-T-1 employs a dual-loop architecture: an inner peak-current loop (using SP pin sensing and slope compensation) and an outer average-LED-current loop (via LP/LN differential sense and COMP-based GM amplifier). Its oscillator supports external synchronization or resistor-programmed operation between 70–700 kHz, with dithering enabled via DITH pin to reduce CISPR 25 EMI emissions.

Fault protection includes cycle-by-cycle switch overload detection (440 mV threshold), LED overcurrent (320 mV), programmable output overvoltage (−1.1 V wrt LP), fixed-output overvoltage (55.5 V), and hiccup-mode recovery (26.5 ms). The IC integrates a 5 V linear regulator (VREG) with 70 mA current limit, used for biasing DR, IREF, and external MOSFET gate drive.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4.2 V to 50 V - supports wide automotive battery range including cold-crank and load-dump conditions.
Max LED String Voltage	53.3 V - enables driving up to 14 white LEDs (3.8 V each) in series without violating absolute max ratings.
Switching Frequency Range	70 kHz to 700 kHz - allows EMI optimization and inductor size trade-off; programmable via ROSC resistor.
Differential Sense Voltage (VIDL)	204 mV typical - sets precise LED current accuracy; used with external RSL to define ILED = 204 mV / RSL.
Overtemperature Shutdown	155 °C - triggers hiccup mode with 20 °C hysteresis to protect against thermal runaway in enclosed headlamp housings.
VREG Output	5.04 V ±0.11 V at 2 mA - powers external circuitry and provides stable reference for DR/IREF dimming networks.
Protection Features	Fixed OV (55.5 V), programmable OV/UV (−1.1 V / −85 mV wrt LP), VIN UVLO (4.2 V), thermal, LED overload, hiccup recovery - ensures robust operation under single-point failures.

Pinout & Package

Package: 16-pin eTSSOP (LP) with exposed thermal pad - designed for high-power dissipation in automotive ambient temperatures up to 125 °C; requires soldering pad to PCB ground plane via multiple vias for RθJC = 2 °C/W.

Pin/Terminal	Circuit Role	Design Meaning
COMP	GM amplifier output	Connects to RC network for outer-loop compensation; determines stability of LED current regulation.
IREF	Analog dimming input	0–1 V input linearly scales LED current from 0% to 100%; also enables soft-start when ramped.
FAULTn	Open-drain fault flag	Active-low signal indicates any fault condition (OV, UV, thermal, LED overload); pulls low to <0.4 V at 1 mA.
OSC	Oscillator programming/sync	Resistor-to-GND sets fSW (70–700 kHz); accepts external clock ≥17 µs period for multi-controller sync.
PWMIN	Dimming/shutdown control	Accepts external PWM (for direct LED on/off), analog voltage (for linear dim), or logic low (for sleep mode).
PWMOUT	p-MOSFET gate driver	Active-low output drives external p-channel MOSFET in series with LED string for precise PWM dimming and fault isolation.
LP / LN	LED current sense inputs	Differential pair measures voltage across RSL; common-mode range extends to 53.3 V for high-side sensing in boost configurations.
VIN	Main supply input	4.2–50 V input with internal UVLO (4.2 V turn-on, 250 mV hysteresis) and 55 V absolute max rating.

Key Features

Feature	Design Value
Programmable spread-spectrum dithering	Reduces peak EMI by modulating fSW ±14.3% at 10 kHz using DITH pin resistor; meets CISPR 25 Class 5 requirements.
Dual dimming architecture	Supports simultaneous analog (IREF) and PWM (external/internal) dimming - enables color correction + brightness control in adaptive lighting.
Comprehensive fault coverage	Detects 7 distinct faults (LED overload, output OV/UV, VIN UVLO, VREG UVLO, PWMOUT UV, thermal) with dedicated FAULTn flag and hiccup recovery.
High-voltage current sense interface	LP/LN inputs rated to 53.3 V common-mode - eliminates need for level-shifting in high-side boost LED configurations.
Integrated 5 V regulator	VREG supplies up to 70 mA - powers DR/IREF networks and external MOSFET gates without requiring auxiliary LDO.

Applications

Automotive Headlights	Daytime Running Lights (DRL)
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current control and fast PWM dimming for beam shaping. IC Role / Device Role / Timing Role: Primary LED current controller managing boost converter topology; regulates string current while coordinating PWMOUT timing with vehicle CAN bus commands. Use Value: Enables <1% current matching across LED channels and <270 ns PWM response time for dynamic beam cutoff, meeting UNECE R149 photometric compliance.	Use Scenario: High-brightness, always-on lighting module mounted in bumper or grille, operating continuously at elevated ambient temperature. IC Role / Device Role / Timing Role: Constant-current controller in buck-boost configuration; maintains stable 150 mA LED current despite 6–16 V battery variation and thermal drift. Use Value: Delivers >92% efficiency across input range and uses thermal shutdown + hiccup recovery to sustain operation at 125 °C ambient without derating.
Fog Lights	Position & Reversing Lights
Use Scenario: Compact, sealed fog lamp assembly requiring high reliability in condensing, corrosive environments with frequent thermal cycling. IC Role / Device Role / Timing Role: LED driver controller in SEPIC topology; provides galvanic isolation between input and output to prevent ground-loop interference and enable flexible PCB layout. Use Value: Eliminates need for optocouplers or isolated DC-DC; achieves <100 ppm/°C LED current drift via 204 mV precision sense and internal slope compensation.	Use Scenario: Rear combination lamp integrating position, brake, and reverse functions with shared LED strings and independent dimming profiles. IC Role / Device Role / Timing Role: Dual-role controller supporting analog dimming (position light intensity) and external PWM (brake flash pattern) via same PWMIN pin. Use Value: Reduces BOM count by enabling one IC to manage three lighting functions; supports <5 ms transition between modes per ISO 15008.

Automotive Headlights

Daytime Running Lights (DRL)

Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current control and fast PWM dimming for beam shaping.

IC Role / Device Role / Timing Role: Primary LED current controller managing boost converter topology; regulates string current while coordinating PWMOUT timing with vehicle CAN bus commands.

Use Value: Enables <1% current matching across LED channels and <270 ns PWM response time for dynamic beam cutoff, meeting UNECE R149 photometric compliance.

Use Scenario: High-brightness, always-on lighting module mounted in bumper or grille, operating continuously at elevated ambient temperature.

IC Role / Device Role / Timing Role: Constant-current controller in buck-boost configuration; maintains stable 150 mA LED current despite 6–16 V battery variation and thermal drift.

Use Value: Delivers >92% efficiency across input range and uses thermal shutdown + hiccup recovery to sustain operation at 125 °C ambient without derating.

Fog Lights

Position & Reversing Lights

Use Scenario: Compact, sealed fog lamp assembly requiring high reliability in condensing, corrosive environments with frequent thermal cycling.

IC Role / Device Role / Timing Role: LED driver controller in SEPIC topology; provides galvanic isolation between input and output to prevent ground-loop interference and enable flexible PCB layout.

Use Value: Eliminates need for optocouplers or isolated DC-DC; achieves <100 ppm/°C LED current drift via 204 mV precision sense and internal slope compensation.

Use Scenario: Rear combination lamp integrating position, brake, and reverse functions with shared LED strings and independent dimming profiles.

IC Role / Device Role / Timing Role: Dual-role controller supporting analog dimming (position light intensity) and external PWM (brake flash pattern) via same PWMIN pin.

Use Value: Reduces BOM count by enabling one IC to manage three lighting functions; supports <5 ms transition between modes per ISO 15008.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM3409QMY/NOPB	Non-synchronous buck controller; no integrated VREG; requires external 5 V bias; lacks programmable OV/UV and dithering.	Targeted at cost-sensitive non-automotive LED drivers; not AEC-Q100 qualified; limited fault coverage (no hiccup, no fixed OV).	Choose LM3409QMY/NOPB only for industrial LED drivers where AEC-Q100, spread-spectrum EMI, or comprehensive fault protection are not required.
MAX16832ATP+	Boost-only controller; integrated high-side N-MOSFET driver; no PWMOUT for external p-MOSFET; no analog dimming input.	Optimized for low-LED-count boost applications (≤8 LEDs); lacks SEPIC/buck-boost support and dual-dimming capability.	Choose MAX16832ATP+ only for simple boost LED strings where analog dimming and topology flexibility are unnecessary.

Compared with LM3409QMY/NOPB and MAX16832ATP+, the A6271KLPTR-T-1 uniquely combines AEC-Q100 qualification, four-switching-topology support, integrated VREG, dual-dimming, and CISPR 25–compliant dithering - making it the only option for full-featured automotive adaptive lighting systems.

Availability

A6271KLPTR-T-1 is available at Aetrix Electronics and suitable for automotive headlight modules, daytime running lights, and fog lamp assemblies requiring stable component supply, long-term lifecycle assurance, and AEC-Q100-compliant performance.

Supply support for A6271KLPTR-T-1 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 sensors for automotive and industrial applications.

The A6271 product line is engineered specifically for automotive LED lighting systems, delivering robust, AEC-Q100-qualified constant-current control with integrated protection and EMI mitigation for headlamps, DRLs, and fog lights.

FAQ

What is the maximum LED string voltage supported by the A6271KLPTR-T-1?

The A6271KLPTR-T-1 supports a maximum LED string voltage of 53.3 V, verified by its fixed-output overvoltage threshold of 55.5 V and LP/LN common-mode input range up to 53.3 V. This enables driving up to 14 white LEDs (3.8 V forward voltage each) in series. Exceeding this voltage risks triggering the fixed OV protection or violating absolute maximum ratings on LP/LN pins.

How does the A6271KLPTR-T-1 implement PWM dimming without external signal generation?

The A6271KLPTR-T-1 implements internal PWM dimming by connecting a resistor between PWMIN and GND to set frequency (e.g., 70 kΩ → 200 Hz), and applying a voltage to the DR pin to control duty cycle (e.g., 1.8 V → 50%). The A6271KLPTR-T-1's internal generator produces the PWM waveform, and PWMOUT drives the external p-MOSFET accordingly - eliminating need for MCU-generated PWM signals.

Can the A6271KLPTR-T-1 be used in buck topology with ground-referenced switch?

Yes, the A6271KLPTR-T-1 explicitly supports buck topology with ground-referenced switch, as confirmed in its datasheet description and functional block diagram. In this configuration, SG drives the low-side n-MOSFET, LP/LN sense the LED current through RSL on the high side, and OVUV monitors output voltage relative to LP. Output undervoltage protection activates if OVUV falls below −85 mV.

What thermal management is required for the A6271KLPTR-T-1 in automotive applications?

The A6271KLPTR-T-1 requires soldering its exposed thermal pad to the PCB ground plane using ≥4 thermal vias (0.3 mm diameter) to achieve RθJC = 2 °C/W. On a 4-layer board per JESD51-7, RθJA is 34 °C/W; junction temperature must stay ≤150 °C. Thermal shutdown triggers at 155 °C with 20 °C hysteresis, so layout must ensure ≤125 °C ambient case temperature under full load.

Does the A6271KLPTR-T-1 support synchronization of multiple controllers?

Yes, the A6271KLPTR-T-1 supports synchronization via its OSC pin: applying an external clock signal with period ≥17 µs (i.e., frequency ≤58.8 kHz) synchronizes multiple A6271KLPTR-T-1 devices. If the external clock fails or goes open-circuit, the device defaults to its internal oscillator at 350 kHz - ensuring fail-safe operation in distributed lighting systems.

A6271KLPTR-T-1 Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 16-TSSOP (0.173", 4.40mm Width) Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: DC DC Controller

Topology:: SEPIC, Step-Down (Buck), Step-Up (Boost)

Internal Switch(s):: No

Number of Outputs:: 1

Voltage - Supply (Min):: 4.2V

Voltage - Supply (Max):: 50V

Voltage - Output:: -

Current - Output / Channel:: -

Frequency:: 70kHz ~ 700kHz

Dimming:: Analog, PWM

Applications:: Lighting

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q100

Mounting Type:: Surface Mount

Supplier Device Package:: 16-eTSSOP-EP

A6271KLPTR-T-1 FAQ

1.How can I place an order for A6271KLPTR-T-1 through Aetrix?

Please submit a Request for Quotation (RFQ) for A6271KLPTR-T-1 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for A6271KLPTR-T-1 reliable?

The price and inventory of A6271KLPTR-T-1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6271KLPTR-T-1 is usually 5 days.

3.What payment methods are accepted for A6271KLPTR-T-1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6271KLPTR-T-1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A6271KLPTR-T-1?

A6271KLPTR-T-1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A6271KLPTR-T-1 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for A6271KLPTR-T-1?

For technical support, including A6271KLPTR-T-1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6271KLPTR-T-1 requirements.

6.How does Aetrix verify that A6271KLPTR-T-1 is sourced from the original manufacturer or authorized distributors?

All A6271KLPTR-T-1 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that A6271KLPTR-T-1 meets industry standards.

7.What is the process for return or replacement of A6271KLPTR-T-1?

All A6271KLPTR-T-1 units undergo pre-shipment inspection (PSI). If there is an issue with A6271KLPTR-T-1, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The A6271KLPTR-T-1 part is unused and in its original packaging.

Return procedure for A6271KLPTR-T-1:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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