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Allegro MicroSystems A6271KLPTR-T
- Part No.:
- A6271KLPTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
A6271KLPTR-T.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16ETSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,001
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Product details
Overview
A6271KLPTR-T from Allegro MicroSystems is an automotive AEC-Q100-qualified DC-DC controller for constant-current high-power LED string drive, supporting boost/buck-boost/buck topologies, 4.2–50 V input, 53.3 V max LED string voltage, and programmable 70–700 kHz switching frequency. It delivers precise analog/PWM dimming control in fog lights, DRLs, and headlight systems.
For engineers reviewing the A6271KLPTR-T datasheet, A6271KLPTR-T pinout, A6271KLPTR-T application, or A6271KLPTR-T equivalent, key selection criteria include its peak current-mode control architecture, integrated fault protection (OV/UV/thermal), external p-channel PWMOUT driver, dither-enabled EMI reduction, and compatibility with logic-level n-MOSFET switches in automotive lighting designs.
Technical Context
The A6271KLPTR-T implements a fixed-frequency, peak current-mode control loop with dual inner/outer feedback: the inner loop regulates switch current via SP pin sensing and slope compensation, while the outer loop maintains average LED current using IREF and COMP amplifier error integration. It supports three switching configurations-boost, buck-boost, and ground-referenced buck-each requiring distinct loop compensation networks.
Its protection architecture includes fixed-output overvoltage (53.3 V), programmable OV/UV via OVUV pin, VIN undervoltage lockout (3.9–4.2 V), VREG UVLO (3.25–3.5 V), LED overcurrent detection (260–380 mV across LP/LN), and hiccup-mode thermal shutdown at 155–170 °C with 20 °C hysteresis. Fault reporting is provided via open-drain FAULTn.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2 to 50 V - supports full automotive battery range including cold-crank and load-dump transients. |
| Max LED String Voltage | 53.3 V - enables driving up to ~14 white LEDs in series at typical forward voltage. |
| Switching Frequency | 70 to 700 kHz - externally programmable via OSC pin resistor; ditherable for CISPR 25 EMI compliance. |
| LED Current Sense | 204 mV typical differential (LP–LN) - sets ILED = 204 mV / RSL; supports accurate closed-loop regulation. |
| Dimming Methods | Analog (IREF 0–1 V), external PWM (PWMIN), internal PWM (DR voltage-controlled) - enables flexible brightness and color tuning. |
| Fault Protection | Fixed OV (53.3 V), programmable OV/UV, VIN/VREG UVLO, thermal shutdown, hiccup recovery - ensures robust operation under single-point failures. |
| AEC-Q100 Grade | Qualified to Grade 1 (–40°C to +125°C junction) - validated for under-hood automotive lighting environments. |
Pinout & Package
16-pin eTSSOP (LP) package with exposed thermal pad soldered to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COMP | GM amplifier output | Connects to RC network for outer-loop compensation; stabilizes LED current regulation. |
| IREF | Analog dimming input | 0–1 V input linearly scales LED current; also provides soft-start ramp when exiting sleep mode. |
| FAULTn | Open-drain fault flag | Active-low indicates any fault condition; requires external pull-up for system-level monitoring. |
| OSC | Oscillator programming/sync | Resistor-to-GND sets fSW; accepts external clock for multi-controller synchronization. |
| DITH | Dither frequency control | Resistor-to-GND configures ±% spread spectrum bandwidth; tie to VREG to disable. |
| DR | Internal PWM duty control | Voltage (0–3.6 V) sets duty cycle per formula: % = 27.81 × VDR; enables two-level brightness without external signal. |
| PWMIN | Multi-function control | Low = sleep/shutdown; high-Z/high = enable; used for external PWM dimming or internal PWM activation. |
| VREG | 5 V regulator output | Stable 4.85–5.15 V supply for external MOSFET gate drive and DR/IREF reference; 25 mA limit. |
| SG | Switch gate driver | Drives external n-channel MOSFET gate; fast 30 ns rise/fall times support high-frequency operation. |
| SP | Slope-compensated current sense | Accepts sensed switch current + sawtooth slope; prevents subharmonic oscillation in boost/buck-boost. |
| GND | Power and signal ground | Common return for all circuits; thermal pad must be soldered to PCB ground plane. |
| OVUV | Programmable OV/UV monitor | Reference input for resistive divider; detects output overvoltage (–1.24 to –1 V wrt LN) or undervoltage (–300 mV). |
| PWMOUT | p-MOSFET gate driver | Active-low output drives external p-channel MOSFET in series with LED string; isolates load during faults. |
| LN / LP | LED current sense inputs | Differential pair (LP+ / LN–) senses RSL voltage; 5–53.3 V common-mode range supports high-voltage strings. |
| VIN | Main power input | 4.2–50 V supply input; includes 3.9–4.2 V UVLO with 250–380 mV hysteresis. |
Key Features
| Feature | Design Value |
|---|---|
| Peak current-mode control | Enables stable operation across boost/buck-boost/buck topologies with minimal external compensation components. |
| Triple dimming architecture | Simultaneous analog (IREF), external PWM (PWMIN), and internal PWM (DR) allows hybrid brightness/color correction schemes. |
| Frequency dithering | Reduces EMI peak emissions by spreading switching energy across ±% band centered on fSW, meeting CISPR 25 Class 5. |
| Comprehensive fault coverage | Detects and responds to 7 distinct fault types-including LED overload, output OV/UV, VIN/VREG UVLO, and thermal-with hiccup recovery. |
| Integrated 5 V regulator | Supplies gate drive for external MOSFETs and reference for DR/IREF pins; eliminates need for external LDO in most designs. |
Applications
| Automotive Fog Lights | Daytime Running Lights (DRL) |
|---|---|
Use Scenario: High-intensity, weather-resistant forward lighting activated automatically with ignition in low-visibility conditions. IC Role / Device Role / Timing Role: Constant-current LED string controller managing 14-LED series stack at 150 mA in boost configuration with thermal foldback. Use Value: Maintains consistent lumen output across –40°C to +125°C ambient; dithered switching minimizes conducted EMI into vehicle CAN bus. | Use Scenario: Always-on, low-power front lighting required by EU/ECE regulations for improved vehicle conspicuity during daylight hours. IC Role / Device Role / Timing Role: Buck-boost configured LED driver delivering 70–100 mA with analog dimming for adaptive brightness based on ambient light sensor input. Use Value: Achieves <1 µA quiescent current in sleep mode; programmable UVLO prevents false turn-on during battery recharge cycles. |
| Automotive Headlights | Reversing Lights |
Use Scenario: High-brightness main beam assembly with dynamic beam shaping and thermal derating for sustained operation. IC Role / Device Role / Timing Role: Boost-mode controller driving dual parallel LED strings with independent PWM dimming via DR pin for asymmetric beam control. Use Value: Fixed 53.3 V OV protection safeguards against LED open-circuit failure; hiccup recovery prevents thermal runaway during prolonged high-load operation. | Use Scenario: Rear-mounted illumination activated only during gear selection into reverse, requiring instant-on capability and vibration resilience. IC Role / Device Role / Timing Role: Ground-referenced buck converter driving 8–10 LED string with external PWMIN-triggered fast turn-on (<270 ns) and fault-isolated shutdown. Use Value: PWMOUT-driven p-MOSFET isolates LED string during short-to-ground faults; FAULTn flag enables immediate ECU diagnostic logging. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A6271-1 | Same silicon die and functional specification; differs only in tape-and-reel packaging (no TR suffix) and minor test screening. | No functional difference; identical use in automotive LED lighting modules. | Select A6271-1 only if legacy procurement or non-reel packaging is required; A6271KLPTR-T is preferred for automated SMT assembly. |
| LM3409QMY/NOPB | Non-synchronous buck controller; lacks boost/buck-boost capability, internal PWM generator, and programmable OV/UV; no dithering. | Limited to lower-voltage buck-only LED strings; requires external PWM source and separate 5 V LDO. | Choose LM3409QMY/NOPB only for cost-sensitive, low-complexity buck-only designs where AEC-Q100 is not mandated. |
Compared with A6271KLPTR-T, A6271-1 offers identical performance and pinout but different packaging, while LM3409QMY/NOPB provides basic buck control at lower integration-making A6271KLPTR-T the sole choice for AEC-Q100-compliant boost/buck-boost LED systems requiring dithered EMI control and triple dimming.
Availability
A6271KLPTR-T is available at Aetrix Electronics and suitable for automotive fog lights, daytime running lights, and headlight systems requiring stable component supply, long-term lifecycle assurance, and AEC-Q100-compliant sourcing.
Supply support for A6271KLPTR-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 magnetic sensing, power ICs, and motor control solutions for automotive and industrial markets.
The A6271 product line is designed specifically for AEC-Q100-compliant, high-current LED lighting control in automotive exterior applications-emphasizing fault resilience, EMI robustness, and multi-topology flexibility.
FAQ
What is the recommended external MOSFET type for use with the A6271KLPTR-T?
The A6271KLPTR-T requires an external logic-level n-channel MOSFET for the main switching function (driven by SG pin) and an external p-channel MOSFET for LED string isolation (driven by PWMOUT). The n-MOSFET must support ≥50 V VDS, low RDS(on) at 4.5 V gate drive, and sufficient Qg to stay within VREG's 25 mA current limit. The p-MOSFET must withstand ≥58 V drain-source voltage and operate with ≤–8 V gate drive relative to LP. A6271KLPTR-T datasheet Figure 1 shows typical part examples and layout guidelines.
How does the A6271KLPTR-T handle LED open-circuit faults?
The A6271KLPTR-T detects LED open-circuit faults via its fixed-output overvoltage protection circuit, which triggers at 53.3 V (typical) measured at the LP pin relative to GND. Upon detection, it immediately disables both SG and PWMOUT outputs, asserts FAULTn low, and initiates a 26.5 ms hiccup timer. After timeout, it performs auto-restart with soft-start via IREF capacitor discharge. This dual-layer OV protection-fixed plus programmable-ensures fail-safe behavior even if the external OVUV feedback network fails open.
Can the A6271KLPTR-T be used in buck configuration with ground-referenced LED cathodes?
Yes, the A6271KLPTR-T explicitly supports buck topology with ground-referenced switch, as confirmed in its Functional Description and Applications sections. In this configuration, the LED string cathode connects to GND, the anode connects to LP, and LN connects to the current-sense resistor's low side. The controller regulates current by modulating the n-channel MOSFET switch between VIN and inductor. Output undervoltage protection activates if LP falls below the OVUV threshold, ensuring safe operation during LED short conditions.
What is the purpose of the DITH pin on the A6271KLPTR-T, and how is it configured?
The DITH pin on the A6271KLPTR-T enables frequency dithering to reduce electromagnetic interference (EMI) peaks by spreading switching energy across a defined band. A resistor from DITH to GND sets the dither amplitude: Δf = ±22 × ROSC/RDITH (% of fOSC). For example, with ROSC = 72 kΩ and target ±50 kHz at 350 kHz, RDITH = 110 kΩ. If dithering is unused, DITH must be tied to VREG-not left floating-to prevent erratic operation. This feature helps A6271KLPTR-T meet CISPR 25 Class 5 emission limits.
Is the A6271KLPTR-T suitable for new automotive design projects?
No-the A6271KLPTR-T is classified as "Not for New Design" per Allegro's official status update dated December 14, 2017. It remains in production solely for existing customer applications and is not recommended for new development due to probable near-term obsolescence. Samples are no longer available. Engineers designing new automotive lighting systems should consult Allegro's current-generation alternatives such as the A8503 or A8516 families, while A6271KLPTR-T continues to be supported for legacy program continuity and repair fulfillment at Aetrix Electronics.
A6271KLPTR-T 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:
- Not For New Designs
- 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:
- 700kHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-eTSSOP-EP
A6271KLPTR-T FAQ
1.How can I place an order for A6271KLPTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A6271KLPTR-T 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 reliable?
The price and inventory of A6271KLPTR-T 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 is usually 5 days.
3.What payment methods are accepted for A6271KLPTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6271KLPTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A6271KLPTR-T?
A6271KLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A6271KLPTR-T 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?
For technical support, including A6271KLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6271KLPTR-T requirements.
6.How does Aetrix verify that A6271KLPTR-T is sourced from the original manufacturer or authorized distributors?
All A6271KLPTR-T 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 meets industry standards.
7.What is the process for return or replacement of A6271KLPTR-T?
All A6271KLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A6271KLPTR-T, 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 part is unused and in its original packaging.
Return procedure for A6271KLPTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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