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Allegro MicroSystems A8504EECTR-T
- Part No.:
- A8504EECTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 26-WFQFN Exposed Pad
- Datasheet:
-
A8504EECTR-T.pdf
- Description:
- IC LED DRVR RGLTR PWM 45MA 26QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,783
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Product details
Overview
A8504EECTR-T from Allegro MicroSystems is a discontinued 8-channel WLED/RGB backlight driver IC with integrated 50 V/2 A boost converter, ±1.2% LED current accuracy, ±1.3% channel matching, and external PWM dimming control. It supports up to 88 LEDs (11×8), drives 45 mA per channel, and targets medium-size LCD backlighting in thin notebooks and portable displays.
For engineers reviewing the A8504EECTR-T datasheet, A8504EECTR-T pinout, A8504EECTR-T application, or A8504EECTR-T equivalent, key selection criteria include its 26-pin QFN/MLP package, 200 kHz–2 MHz adjustable switching frequency, 800 mV LED regulation voltage, OVP adjustability (30–45 V), and active current sharing across eight independent sinks - all critical for uniform brightness and thermal-safe backlight design.
Technical Context
The A8504EECTR-T integrates a constant-frequency current-mode boost controller with pulse-by-pulse overcurrent protection (2 A limit) and programmable overvoltage protection via ROVP. Its eight current sinks operate with 800 mV compliance voltage and support parallel channel configuration via SEL1–SEL3 logic inputs.
LED current is set by an external resistor on ISET (1.23 V reference), yielding 40–100 μA ISET range and internal 460× gain to deliver up to 45 mA per enabled channel. Dimming is implemented via digital PWM input (100–400 Hz optimal), with 6 μs typical turn-on delay and no audible ceramic capacitor noise during modulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage | 4.2–5.5 V - powers IC core; separate VBAT (5–25 V) supplies boost stage |
| LED Current Accuracy | ±1.2% - ensures consistent luminance across channels without calibration |
| Current Matching | ±1.3% (LED1–LED6) - maintains uniform brightness in multi-string configurations |
| Switching Frequency | 200 kHz–2 MHz - adjustable via RFSET resistor; SKIP pin divides frequency by 4 |
| OVP Threshold | 28–34 V - externally set via ROVP; protects against open-LED overvoltage events |
| Thermal Shutdown | 165°C (40°C hysteresis) - prevents damage during sustained overload or poor heatsinking |
| LED Sink Rating | 45 mA per channel, 21 V max - supports high-brightness white/RGB LEDs with margin for Vf drift |
Pinout & Package
The A8504EECTR-T is housed in a 26-pin, 4 mm × 4 mm QFN/MLP package (0.75 mm height) with exposed thermal pad. Pin functions are validated per Allegro A8504 datasheet Rev. 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | IC supply input | Accepts 4.2–5.5 V; powers internal circuitry and gate drivers |
| PGND / LGND / AGND / GND | Ground terminals | Separate power (PGND), LED (LGND), analog (AGND), and digital (GND) grounds - must be star-connected at thermal pad |
| SW | Boost switch output | Drives external inductor; integrates 50 V/2 A DMOS switch with current limiting |
| OVP | Overvoltage sense input | Monitors output via ROVP; triggers shutdown when current exceeds 49 μA |
| ISET | LED current reference | 1.23 V reference; RISET sets ISET = 1.23 / RISET (mA), scaled ×460 to LED sinks |
| PWM | Digital dimming control | Active-high enable; 100–400 Hz PWM yields optimal dimming linearity and minimal turn-on error |
| SEL1–SEL3 | Channel enable logic | 3-bit binary selects 1–8 active LEDx outputs (e.g., SEL1=H, SEL2=L, SEL3=H → LED1–LED6) |
| LED1–LED8 | Current sink outputs | Each sinks up to 45 mA; open-LED detection disables faulty string from boost regulation loop |
Key Features
| Feature | Design Value |
|---|---|
| Active current sharing | ±1.3% typical matching across enabled LED strings - eliminates brightness variation without external feedback |
| No-audible-noise PWM dimming | Eliminates piezoelectric ringing in ceramic capacitors during 100–400 Hz PWM - critical for quiet portable devices |
| Open LED fault recovery | Identifies and removes open strings from boost regulation while maintaining operation of remaining channels - improves system robustness |
| Adjustable OVP with redundancy option | ROVP + optional Zener (DZ) provides dual-layer protection up to 47 V - prevents catastrophic failure during LED disconnection |
| Flexible channel configuration | SEL1–SEL3 pins select 1–8 active outputs; parallel sinking enables 50–200 mA total per group - simplifies layout for varying LED counts |
Applications
| Thin Notebook Displays | LCD TV Backlight |
|---|---|
Use Scenario: Driving 6–8 parallel LED strings (e.g., 8S6P) in 13–15.6″ notebook panels with 40 mA/channel and 3.5 V forward voltage. IC Role / Device Role / Timing Role: WLED backlight driver with integrated boost and precision current sinks - regulates string current and manages dynamic voltage headroom. Use Value: ±1.2% current accuracy ensures uniform screen luminance; 2 MHz switching minimizes inductor size for ultra-thin chassis integration. | Use Scenario: Medium-size LCD TV backlight (22–32″) using 8-channel 11×8 LED matrix (88 total LEDs) at 45 mA/channel. IC Role / Device Role / Timing Role: Multi-output constant-current driver with OVP and thermal shutdown - sustains stable brightness under variable ambient temperature and input ripple. Use Value: Active current sharing (±1.3%) prevents localized hot spots; open-LED protection maintains partial backlight function during single-string failure. |
| RGB Automotive Displays | Portable DVD Player Backlight |
Use Scenario: RGB backlight for infotainment displays requiring independent red/green/blue string control and color balance. IC Role / Device Role / Timing Role: Precision current sink array with external PWM dimming - enables synchronized intensity control across R/G/B channels. Use Value: 800 mV LED regulation voltage accommodates low-Vf red LEDs (2.2 V); SELx logic allows dynamic reconfiguration of active channels per color. | Use Scenario: Compact DVD player with space-constrained PCB and battery-powered 5–24 V VBAT input. IC Role / Device Role / Timing Role: Integrated boost + 8-sink driver - eliminates need for discrete boost controller and current regulators. Use Value: 4 mm × 4 mm QFN package reduces board area; no pull-up resistors required for ESD-capacitor-equipped LED modules - lowers BOM count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar WLED backlight driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AL8860SP-13 | Single-channel, 1.5 A buck-boost driver; no integrated current sinks; requires external MOSFETs and sense resistors | Designed for high-power single-string applications (e.g., automotive center stack), not multi-string medium-LCD backlighting | Not suitable for direct replacement; lacks 8-channel current matching and SELx control logic |
| LM3409QMY/NOPB | High-side N-channel controller only; no integrated FET or current sinks; requires external compensation and sensing | Targeted at industrial LED lighting with >1 A output; no native PWM dimming interface or channel enable logic | Requires full redesign; does not support A8504EECTR-T's plug-and-play 8-sink architecture or open-LED recovery |
Compared with AL8860SP-13 and LM3409QMY/NOPB, the A8504EECTR-T delivers fully integrated 8-channel current regulation, factory-trimmed matching, and application-specific features like SELx channel selection and no-audible-noise PWM - making it uniquely suited for medium-display backlighting where compactness, uniformity, and reliability are prioritized over raw power scalability.
Availability
A8504EECTR-T is available at Aetrix Electronics and suitable for legacy system repair, spare part fulfillment, and end-of-life inventory management requiring stable component supply for thin notebook displays, portable DVD players, and medium-size LCD TV backlight modules.
Supply support for A8504EECTR-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 motion control, energy-efficient power conversion, and precision analog solutions.
The A8504 product line was engineered specifically for medium-format LCD backlighting, integrating boost conversion and multi-channel current regulation to replace discrete solutions in space- and cost-sensitive consumer electronics.
FAQ
Is the A8504EECTR-T still in production?
No, the A8504EECTR-T is a discontinued product. Allegro MicroSystems ceased production as of December 3, 2012. It is not recommended for new designs. Aetrix Electronics offers limited legacy stock for repair and maintenance use only, with full traceability and documentation.
What is the maximum number of LEDs the A8504EECTR-T can drive?
The A8504EECTR-T can drive up to 88 LEDs in an 11-series × 8-parallel configuration (e.g., 11 LEDs per string × 8 strings), assuming 3.5 V forward voltage and 40 mA per string. Total output capability depends on VBAT, boost efficiency, and thermal design - verified in Allegro's typical application circuits.
How does the A8504EECTR-T handle open LED faults?
The A8504EECTR-T detects open LED strings via voltage collapse on the corresponding LEDx pin. It removes the faulty string from the boost regulation loop while maintaining normal operation of remaining channels. The boost output adjusts dynamically to supply only the active strings, preventing overvoltage and excessive power dissipation.
Can the A8504EECTR-T be used with LED modules that include ESD capacitors?
Yes, the A8504EECTR-T explicitly supports LED modules with integrated ESD capacitors (e.g., 0.1 μF per string). Its architecture eliminates the need for external pull-up resistors on LEDx pins, reducing component count and simplifying layout - confirmed in Allegro's Figure 12 application circuit.
What is the purpose of the SKIP pin on the A8504EECTR-T?
The SKIP pin on the A8504EECTR-T controls switching frequency division: when pulled high, it divides the base RFSET-set frequency by 4 (e.g., 2 MHz → 500 kHz), reducing switching losses and improving light-load efficiency. When low, full RFSET-determined frequency operates - enabling optimization across load conditions without hardware change.
A8504EECTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 26-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 8
- Voltage - Supply (Min):
- 4.2V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 45mA
- Frequency:
- 2MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 26-QFN/MLP (4x4)
A8504EECTR-T FAQ
1.How can I place an order for A8504EECTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A8504EECTR-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 A8504EECTR-T reliable?
The price and inventory of A8504EECTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A8504EECTR-T is usually 5 days.
3.What payment methods are accepted for A8504EECTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A8504EECTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A8504EECTR-T?
A8504EECTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A8504EECTR-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 A8504EECTR-T?
For technical support, including A8504EECTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A8504EECTR-T requirements.
6.How does Aetrix verify that A8504EECTR-T is sourced from the original manufacturer or authorized distributors?
All A8504EECTR-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 A8504EECTR-T meets industry standards.
7.What is the process for return or replacement of A8504EECTR-T?
All A8504EECTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A8504EECTR-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 A8504EECTR-T part is unused and in its original packaging.
Return procedure for A8504EECTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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