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Diodes Incorporated AL8861WT-7
- Part No.:
- AL8861WT-7
- Manufacturer:
- Diodes Incorporated
- Category:
- LED Drivers
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
AL8861WT-7.pdf
- Description:
- IC LED DRVR RGLTR PWM 1A TSOT25
- Quantity:
- Payment:
- Shipping:
Inventory:127,785
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Product details
Overview
AL8861WT-7 from Diodes Incorporated is a hysteresis-mode DC-DC buck LED driver IC with integrated 40V NDMOS switch, designed to drive series-connected LEDs from 4.5V–40V input. It delivers up to 1.5A output current (SOT89-5/MSOP-8EP), achieves 97% peak efficiency, supports analog/PWM dimming via single VSET pin, and provides inherent open-circuit and RS short protection - used in low-voltage industrial lighting and LED retrofit systems.
For engineers reviewing the AL8861WT-7 datasheet, AL8861WT-7 pinout, AL8861WT-7 application, or AL8861WT-7 equivalent, key selection criteria include verified 1.5A continuous output capability in SOT89-5 package, ±13% current sense hysteresis, 0.2V shutdown threshold on VSET, 1MHz max switching frequency, and thermal shutdown at +150°C junction temperature.
Technical Context
The AL8861WT-7 operates in constant-current hysteresis mode, using internal high-side current sensing referenced to VIN via external RS resistor to regulate LED current. Its comparator monitors voltage across RS (typical 100mV threshold) and toggles the integrated NDMOS switch based on upper/lower hysteresis bands, eliminating need for external compensation.
Dimming control is unified on VSET: analog dimming uses 0.3–2.5V DC for 5–100% linear current scaling; PWM dimming accepts logic-level signals <500Hz for 1–100% duty-cycle control; soft-start is extended by adding capacitor from VSET to GND (1.5ms/nF). Standby current drops to 55–100µA when VSET ≤ 0.2V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports wide-range DC inputs including 12VAC rectified, 24V industrial rails, and automotive battery variations. |
| Max Output Current | 1.5A - confirmed for SOT89-5 and MSOP-8EP packages; enables driving high-brightness LED strings up to ~40W. |
| Current Sense Threshold | 100mV ±4% - sets nominal LED current as IOUT = 0.1 / RS; enables precise external current programming with <5% typical accuracy. |
| Switching Frequency | Up to 1MHz - allows compact magnetics; typical 250kHz at 16VIN/9.6VOUT, adjustable via L and C selection. |
| VSET Control Range | 0.3V–2.5V for analog dimming; 0V–0.2V for shutdown - single-pin interface simplifies microcontroller or potentiometer interfacing. |
| Thermal Protection | +150°C trip with +30°C hysteresis - prevents latch-up during overload or poor heatsinking; resumes operation after cooldown. |
| Efficiency | Up to 97% - achieved at optimal load/VIN; reduces thermal load in enclosed fixtures and extends lifetime. |
Pinout & Package
AL8861WT-7 is supplied in Pb-free SOT89-5 package (5-pin, single-ended leaded) with exposed thermal pad. Pin 1 = GND, Pin 2 = ISENSE, Pin 3 = VIN, Pin 4 = LX, Pin 5 = VSET. Thermal resistance θJA = 116°C/W on 1"×1" 2oz FR-4 board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Power and signal reference ground | Return path for internal logic, current sense amplifier, and LX switch; must be low-impedance connection to minimize noise coupling. |
| ISENSE (Pin 2) | High-side current sense input | Connects to RS resistor between VIN and this pin; senses voltage drop to regulate average LED current; 8µA input bias current. |
| VIN (Pin 3) | Main power input | Supplies internal regulator and switch; requires ≥10µF X7R ceramic decoupling capacitor placed adjacent to pin. |
| LX (Pin 4) | Switch node output | Drain of internal 40V NDMOS; connects to inductor and freewheeling diode anode; handles high dI/dt switching transitions. |
| VSET (Pin 5) | Multi-function control pin | Accepts DC voltage (0.3–2.5V) or PWM signal for dimming; <0.2V disables output; capacitor to GND adds soft-start delay (1.5ms/nF). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 40V NDMOS switch | Eliminates external MOSFET, reducing BOM count and PCB area while maintaining 1.5A capability in SOT89-5. |
| Single-pin dimming & enable | VSET pin supports analog dimming (5–100%), PWM dimming (<500Hz), and hardware shutdown - simplifies system-level control architecture. |
| Inherent open-circuit LED protection | Auto-shutdown if LED string opens; no external fault detection circuitry required - improves reliability in field-deployed lighting. |
| RS short-circuit protection | Detects shorted current-sense resistor and disables output - prevents unregulated high-current fault conditions. |
| Soft-start programmability | Default 0.1ms start time optimized for PWM dimming fidelity; extended via external capacitor (1.5ms/nF) for inrush current limiting. |
Applications
| LED Retrofit for Low Voltage Halogen | Low Voltage Industrial Lighting |
|---|---|
Use Scenario: Replacing 12V AC halogen lamps in track lighting or under-cabinet fixtures with efficient LED modules. IC Role / Device Role / Timing Role: Constant-current buck controller regulating LED string current independent of input ripple or transformer regulation drift. Use Value: Enables direct 12VAC-to-LED conversion with >90% efficiency and flicker-free dimming via existing wall-mounted TRIAC dimmers (when paired with compatible rectifier/filter). | Use Scenario: Powering IP67-rated LED luminaires in factory floor, warehouse, or outdoor signage where wide input range and robust protection are critical. IC Role / Device Role / Timing Role: Primary LED current regulator with overtemperature and open-circuit fault response built into silicon - no firmware or external monitoring needed. Use Value: Delivers stable 1.5A output across -40°C to +85°C ambient, with automatic shutdown at +150°C junction temperature to prevent thermal runaway in sealed enclosures. |
| LED Backlighting | Illuminated Signs |
Use Scenario: Driving edge-lit LCD backlights in kiosks, medical displays, or industrial HMIs requiring uniform brightness and low EMI. IC Role / Device Role / Timing Role: High-frequency (up to 1MHz) hysteresis controller minimizing inductor size and enabling tight current matching across parallel strings. Use Value: Achieves <1% LED current mismatch between channels using matched RS resistors, supporting consistent color and luminance in multi-zone backlight systems. | Use Scenario: Powering channel letters, lightboxes, or architectural accent lighting with long LED strings and variable ambient temperatures. IC Role / Device Role / Timing Role: Buck converter with integrated switch and current sense, configured for 36VOUT at 1.2A using 0.083Ω RS resistor and 68μH inductor. Use Value: Supports 40W output with single IC, eliminating need for multiple drivers; inherent open-circuit protection prevents catastrophic failure if one LED fails open in series string. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AL8861Q-13 | Automotive-grade variant with AEC-Q100 qualification, same pinout and electrical specs but extended temperature range (-40°C to +125°C TJ). | Required for automotive interior lighting; not necessary for commercial/industrial use. | Select AL8861Q-13 only when AEC-Q100 compliance and higher junction temperature rating are mandatory. |
| MPQ4425AGU-AEC1-P | Monolithic synchronous buck LED driver (40V, 1.2A), fixed-frequency (200kHz–2.2MHz), requires external current sense resistor and separate enable/dim pins. | Lacks single-pin dimming; needs two control signals; offers spread-spectrum EMI reduction. | Choose MPQ4425AGU-AEC1-P when EMI compliance is critical and board space allows additional control routing. |
Compared with AL8861WT-7, AL8861Q-13 adds automotive qualification without changing functionality, while MPQ4425AGU-AEC1-P trades integrated dimming simplicity for flexible frequency control and lower EMI - making AL8861WT-7 optimal for cost-sensitive, space-constrained industrial LED systems requiring minimal external components.
Availability
AL8861WT-7 is available at Aetrix Electronics and suitable for LED retrofit for low voltage halogen, low voltage industrial lighting, and illuminated signs requiring stable component supply and RoHS-compliant packaging.
Supply support for AL8861WT-7 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
Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal ICs, with emphasis on power management, signal integrity, and lighting solutions.
The AL8861 belongs to Diodes' LED driver product line, engineered for high-efficiency, low-component-count constant-current regulation in non-isolated buck topologies targeting commercial and industrial solid-state lighting.
FAQ
What is the maximum recommended output current for AL8861WT-7 in SOT89-5 package?
The AL8861WT-7 in SOT89-5 package supports up to 1.5A continuous output current, validated per datasheet DS39435 Rev. 5–2 under recommended operating conditions (TA ≤ +85°C, proper PCB copper area). This rating assumes use of 0.067Ω current-sense resistor and adequate thermal management; exceeding 1.5A risks thermal shutdown activation.
Can AL8861WT-7 operate directly from 12VAC input?
Yes - AL8861WT-7 can operate from rectified 12VAC input when paired with a bridge rectifier and bulk capacitor, as shown in the Typical Applications Circuit (page 2 of DS39435). Input must be filtered to maintain ≥4.5V minimum after rectification; peak voltage must not exceed 42V absolute maximum rating.
How does the VSET pin function for analog versus PWM dimming?
VSET accepts either analog DC voltage (0.3–2.5V) for linear 5–100% current scaling or PWM signal (<500Hz) for digital dimming. For analog, output current is proportional to VSET voltage; for PWM, average current equals IOUTNOM × duty cycle. Below 0.2V, output shuts down; above 2.5V, current clamps at 100%.
What protection features are built into AL8861WT-7?
AL8861WT-7 integrates LED open-circuit protection (auto-shutdown if string opens), RS short-circuit protection (disables output if sense resistor shorts), overtemperature protection (shuts down at +150°C TJ with +30°C hysteresis), and inherent current limiting (peak inductor current capped at 2A). No external fault-detection circuitry is required.
AL8861WT-7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- SOT-23-5 Thin, TSOT-23-5
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 4.5V
- Voltage - Supply (Max):
- 40V
- Voltage - Output:
- 36V
- Current - Output / Channel:
- 1A
- Frequency:
- 1MHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight, Lighting, Signage
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-25
AL8861WT-7 FAQ
1.How can I place an order for AL8861WT-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for AL8861WT-7 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 AL8861WT-7 reliable?
The price and inventory of AL8861WT-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AL8861WT-7 is usually 5 days.
3.What payment methods are accepted for AL8861WT-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AL8861WT-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AL8861WT-7?
AL8861WT-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AL8861WT-7 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 AL8861WT-7?
For technical support, including AL8861WT-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AL8861WT-7 requirements.
6.How does Aetrix verify that AL8861WT-7 is sourced from the original manufacturer or authorized distributors?
All AL8861WT-7 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 AL8861WT-7 meets industry standards.
7.What is the process for return or replacement of AL8861WT-7?
All AL8861WT-7 units undergo pre-shipment inspection (PSI). If there is an issue with AL8861WT-7, 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 AL8861WT-7 part is unused and in its original packaging.
Return procedure for AL8861WT-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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