My Inquiry
My Account
Allegro MicroSystems A8500EECTR-T
- Part No.:
- A8500EECTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 26-WFQFN Exposed Pad
- Datasheet:
-
A8500EECTR-T.pdf
- Description:
- IC LED DRVR RGLTR PWM 25MA 26QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,092
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
A8500EECTR-T from Allegro MicroSystems is a flexible multi-output WLED/RGB backlight driver IC for medium-size LCD displays, integrating an adjustable-frequency current-mode boost converter (200 kHz–2 MHz) and eight matched 25 mA LED current sinks with ±1.2% regulation accuracy and ±1.5% channel matching. It supports up to 96 LEDs (12 series × 8 parallel), operates from 4.2–5.5 V input, delivers up to 47 V output, and enables three dimming modes: serial EN pulse, digital PWM, and analog APWM control - used in thin notebook displays and portable DVD players.
For engineers reviewing the A8500EECTR-T datasheet, A8500EECTR-T pinout, A8500EECTR-T application, or A8500EECTR-T equivalent, key selection considerations include its 26-pin QFN/MLP (4 mm × 4 mm) package, –40°C to +85°C ambient rating, integrated 50 V/2 A DMOS switch, OVP programmability (30–47 V), and support for open-LED fault recovery without system shutdown.
Technical Context
The A8500EECTR-T implements a constant-frequency current-mode boost controller with external frequency setting via RFSET (13–40 kΩ) and SKIP pin-selectable 4× frequency division. Its transconductance error amplifier (60 dB gain, 3 MHz GBW) drives an external COMP network for loop stability across wide LED string voltage ranges.
Eight independent current sinks are controlled by SEL1–SEL3 logic (enabling 1–8 channels), each regulated to 500 mV compliance voltage and capable of sinking up to 25 mA with active current sharing. Dimming is implemented via three mutually exclusive paths: EN pin serial programming (16-level discrete steps), PWM pin on/off gating (100–400 Hz optimal), or APWM pin analog duty-cycle scaling (20 kHz–2 MHz).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage | 4.2–5.5 V - powers IC directly from 5 V rail; separate VBAT (5–25 V) supplies boost inductor for higher power. |
| Boost Output Voltage | Up to 47 V - sufficient to drive 12-series WLED strings (Vf = 3.2 V) or RGB configurations with margin. |
| LED Current per Channel | Up to 25 mA - set via RISET (10–30 kΩ); 210× internal gain ensures ±1.2% absolute accuracy and ±1.5% matching. |
| Switching Frequency | 200 kHz–2 MHz - selectable via RFSET resistor and SKIP pin; light-load efficiency improved by dividing frequency. |
| OVP Threshold | Programmable 30–47 V - set by ROVP resistor (e.g., 270 kΩ → ~45 V nominal); protects against overvoltage faults. |
| Thermal Shutdown | 165°C with 40°C hysteresis - prevents damage during sustained overload or poor PCB thermal design. |
| Dimming Interface Options | Three independent methods: EN (serial pulse train), PWM (digital gate), APWM (analog duty-cycle modulation) - no simultaneous use permitted. |
Pinout & Package
The A8500EECTR-T is housed in a 26-pin, 4 mm × 4 mm QFN/MLP package (suffix EC) with 0.75 mm nominal height and exposed thermal pad (EP) connected to PGND/LGND for enhanced thermal dissipation. Pin pitch is 0.5 mm; land pattern follows IPC-7351 QFN40P400X400X80-29M.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (1,21) | Power ground return for boost switch and internal circuitry | Must be low-inductance connection to PCB ground plane; shares thermal pad (EP) for heat transfer. |
| LGND (11) | Power ground return for LED current sinks | Separate from PGND in layout to minimize noise coupling into current-sink reference path. |
| VIN (25) | IC supply input (4.2–5.5 V) | Requires local 0.1 µF ceramic decoupling; not used for high-current boost path. |
| SW (23,24) | Drain node of integrated 50 V/2 A DMOS boost switch | Connects to inductor and flyback diode; high dv/dt node requiring tight layout and guard ring. |
| OVP (22) | Overvoltage sense input | Connected to output capacitor via ROVP; triggers shutdown if current exceeds 54.9 µA (≈VOVP > programmed threshold). |
| LED1–LED8 (7–10,12–15) | Current-sink outputs (25 mA max each) | Each regulates LED string to 500 mV compliance; open-LED detection disables faulty channel from boost control loop. |
| SEL1–SEL3 (16–18) | Channel enable logic inputs | 3-bit binary selects 1–8 active LEDx outputs per Table 1; all unused pins must be tied to AGND or VIL. |
| EN (19) | Enable and serial dimming input | Pull-high to enable; pulse train sets ILEDx level in 16 discrete steps (0–100% in 6.25% increments); tHI(init) = 256/64 switching pulses. |
| PWM (20) | Digital on/off dimming input | Logic-level signal (VIH ≥ 1.5 V) gates all enabled LEDx sinks; optimal 100–400 Hz for linearity and flicker avoidance. |
| APWM (6) | Analog PWM dimming input | Accepts 20 kHz–2 MHz logic-level PWM; multiplies ISET by duty cycle to scale LED current continuously. |
| ISET (5) | Reference current programming pin | RISET to AGND sets ISET = 1.23 V / RISET; determines full-scale LED current (e.g., 12 kΩ → 102.5 µA → 21.5 mA). |
| FSET (4) | Boost frequency programming pin | RFSET to AGND sets fSW = 26.03 / RFSET (MHz); SKIP = VIH divides frequency by 4. |
| COMP (3) | Error amplifier compensation node | External RC network stabilizes boost loop; critical for transient response and EMI control across load/VOUT range. |
| AGND (26) | Analog ground reference | Low-noise reference for ISET, APWM, EN, PWM, SELx; must be isolated from PGND/LGND except at single-point star ground. |
Key Features
| Feature | Design Value |
|---|---|
| Active current sharing across LED strings | ±1.2% typical current accuracy and ±1.5% channel-to-channel matching ensure uniform display brightness without per-string calibration. |
| Triple dimming architecture | EN (serial), PWM (digital gate), and APWM (analog modulation) provide flexibility for EMI-sensitive, resolution-critical, or low-flicker applications. |
| No audible ceramic capacitor noise | Boost controller avoids sub-audible switching frequencies and modulates at >20 kHz during APWM dimming to eliminate piezoelectric whine. |
| Open-LED fault tolerance | Individual LED string disconnect detection removes only the faulty channel from regulation, allowing remaining strings to operate normally without overvoltage stress. |
| Adjustable overvoltage protection | ROVP resistor sets OVP threshold from 30 V to 47 V; dual-protection option adds Zener diode for redundancy against resistor open-circuit failure. |
Applications
| Thin Notebook Displays | LCD TV Backlight |
|---|---|
Use Scenario: Driving 48–96 WLEDs in edge-lit or direct-lit backlight assemblies for 13–15.6-inch notebooks with dynamic contrast control. IC Role / Device Role / Timing Role: Primary WLED driver providing regulated current, programmable dimming, and boost voltage generation synchronized to display frame timing. Use Value: Enables high-brightness, low-power backlighting with <5% current mismatch across strings - critical for uniform luminance and minimal grayscale banding. | Use Scenario: Powering 64–96 WLEDs in 32–43-inch LCD TV backlights using 8-channel parallel architecture with local dimming zones. IC Role / Device Role / Timing Role: Multi-string LED controller supporting independent channel enable/disable via SEL pins and fast-response APWM dimming for local dimming algorithms. Use Value: Delivers 25 mA per channel with ±1.5% matching and open-LED recovery - maintains zone integrity and prevents catastrophic failure during LED aging or ESD events. |
| Portable DVD Players | GPS Navigation Systems |
Use Scenario: Illuminating 16–32 WLEDs in compact 4–7-inch TFT-LCD panels powered from single-cell Li-ion (3.0–4.2 V) with boost from VBAT. IC Role / Device Role / Timing Role: Integrated boost + current sink IC eliminating external MOSFET and reducing BOM count; EN pin serial dimming simplifies microcontroller GPIO usage. Use Value: Achieves 1000:1 combined dimming range (via ISET + PWM) while maintaining <3% current error at 2 MHz APWM - essential for battery-life optimization and sunlight readability. | Use Scenario: Backlighting 24–48 WLEDs in automotive-grade GPS units operating across –40°C to +85°C ambient with ESD-protected LED modules. IC Role / Device Role / Timing Role: Robust LED driver with thermal shutdown (165°C), OVP, and no-pull-up design for ESD-capacitor-equipped LED arrays. Use Value: Eliminates need for external pull-ups on LED lines, reduces component count, and sustains operation under thermal stress - validated for extended automotive temperature cycling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar WLED backlight driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3409QMY/NOPB | Single-channel buck-boost LED driver; no integrated current sinks; requires external FET and sense resistors. | Designed for high-power single-string automotive lighting; lacks multi-channel matching and serial dimming. | Choose when driving one high-current string (>500 mA) with analog/digital dimming, not multi-string display backlighting. |
| TPS61165DRVR | 6-channel WLED driver with 30 V max output; fixed 1.2 MHz switching; no APWM or serial dimming; ±3% current matching. | Targeted at smaller displays (≤7″); lower voltage headroom limits string count; no OVP programming. | Choose for cost-sensitive portable displays where 30 V output and basic PWM dimming suffice and thermal margin is adequate. |
Compared with LM3409QMY/NOPB and TPS61165DRVR, the A8500EECTR-T uniquely integrates eight precision current sinks, triple dimming interfaces, programmable OVP, and open-LED recovery - making it suitable for medium-size LCDs requiring high channel count, tight current matching, and robust fault handling without external components.
Availability
A8500EECTR-T is available at Aetrix Electronics and suitable for thin notebook displays, LCD TV backlight systems, and portable DVD player designs requiring stable component supply and long-term industrial availability.
Supply support for A8500EECTR-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 and manufacturer of high-performance magnetic sensing and power IC solutions, specializing in motion control, energy-efficient power conversion, and precision analog interfaces.
The A8500 product line was developed specifically for medium-format LCD backlighting applications, emphasizing multi-string current matching, flexible dimming, and robust fault protection in space-constrained consumer and automotive displays.
FAQ
What is the maximum number of LEDs the A8500EECTR-T can drive, and how is that configured?
The A8500EECTR-T can drive up to 96 LEDs (12 series × 8 parallel) at 20 mA per string. This is achieved by enabling all eight LEDx channels via SEL1–SEL3 = 111, configuring each string with up to 12 WLEDs (Vf = 3.2 V), and setting ISET to deliver 20 mA per channel using RISET = 12.3 kΩ. The boost converter supplies up to 47 V to accommodate the total forward voltage.
Does the A8500EECTR-T support dimming without a microcontroller, and if so, how?
Yes, the A8500EECTR-T supports microcontroller-free dimming via its EN pin: applying a serial pulse train (0.5–100 µs pulse width) programs LED current in 16 discrete levels (0–100% in 6.25% steps). No firmware or communication protocol is required - only a simple GPIO toggling signal synchronized to the internal oscillator.
What is the purpose of the SKIP pin on the A8500EECTR-T, and how does it affect efficiency?
The SKIP pin on the A8500EECTR-T reduces boost switching frequency by a factor of 4 when pulled high, lowering switching losses at light loads. For example, with RFSET = 26.1 kΩ, fSW drops from 1 MHz to 250 kHz. This improves light-load efficiency by up to 8% (per Figure 6 data) while maintaining regulation - critical for battery-powered display standby modes.
How does the A8500EECTR-T handle an open LED fault, and does it shut down the entire system?
The A8500EECTR-T detects open LED faults by monitoring LEDx pin voltage; if a string opens, that pin falls to 0 V and the OVP comparator triggers. The faulty channel is removed from the boost regulation loop, but remains electrically connected. Remaining enabled LED strings continue normal operation at full current - no system shutdown occurs, preserving display functionality during partial failure.
Can the A8500EECTR-T be used with LED modules that include ESD protection capacitors, and what design consideration applies?
Yes, the A8500EECTR-T is designed for LED modules with ESD capacitors: its LEDx drivers require no external pull-up resistors, eliminating conflicts with shunt capacitance. Layout best practice is to place 0.1 µF ESD capacitors directly across each LED string (as shown in Figure 16), ensuring low-impedance AC paths without affecting DC current regulation or dimming fidelity.
A8500EECTR-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:
- 25mA
- Frequency:
- 2MHz
- Dimming:
- Analog, Multi-Step, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 26-QFN/MLP (4x4)
A8500EECTR-T FAQ
1.How can I place an order for A8500EECTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A8500EECTR-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 A8500EECTR-T reliable?
The price and inventory of A8500EECTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A8500EECTR-T is usually 5 days.
3.What payment methods are accepted for A8500EECTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A8500EECTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A8500EECTR-T?
A8500EECTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A8500EECTR-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 A8500EECTR-T?
For technical support, including A8500EECTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A8500EECTR-T requirements.
6.How does Aetrix verify that A8500EECTR-T is sourced from the original manufacturer or authorized distributors?
All A8500EECTR-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 A8500EECTR-T meets industry standards.
7.What is the process for return or replacement of A8500EECTR-T?
All A8500EECTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A8500EECTR-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 A8500EECTR-T part is unused and in its original packaging.
Return procedure for A8500EECTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
A8500EECTR-T Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
