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

Diodes Incorporated AL1678-20BS7-13

Name: AL1678-20BS7-13
Brand: Diodes Incorporated
SKU: AL1678-20BS7-13
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AL1678-20BS7-13

Manufacturer:: Diodes Incorporated

Category:: LED Drivers

Package:: 8-SOIC (0.154", 3.90mm Width), 7 Leads

Datasheet:: AL1678-20BS7-13.pdf

Description:: IC LED DRIVER OFFL NO 2A 7SO

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Product details

Overview

AL1678-20BS7-13 from Diodes Incorporated is a universal AC-input (85–277 VAC), boundary-conduction-mode (BCM) buck LED driver IC with integrated 500 V/2.0 A MOSFET, ±3% current regulation accuracy, 90%+ efficiency, and thermal fold-back protection. It delivers constant-current output for non-isolated retrofit LED lamps using a single-winding inductor and minimal external components.

For engineers reviewing the AL1678-20BS7-13 datasheet, AL1678-20BS7-13 pinout, AL1678-20BS7-13 application, or AL1678-20BS7-13 equivalent, key selection criteria include its SO-7 package, internal 500 V MOSFET rating, 0.4 V current-sense reference, 14.5 V startup threshold, and thermal fold-back activation at +140°C.

Technical Context

The AL1678-20BS7-13 implements valley-switching control in BCM to minimize switching loss and simplify EMI compliance. Its t_ON range (400 ns–35 µs) and t_OFF range (6–200 µs) are tightly constrained to maintain stable boundary operation across input voltage fluctuations.

Current regulation relies on peak inductor current sensing against a 0.4 V internal reference, with line compensation via the LC pin and open-load detection via ROVP. Fault management includes latched OTP at +170°C, UVLO (14.5 V start / 8.5 V hold), and leading-edge blanking for noise immunity.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	85–277 VAC universal AC input enables single-design compatibility across global mains voltages.
Output Current Accuracy	±3% tolerance ensures stable LED brightness across line/load variations without trimming.
Integrated MOSFET	500 V drain rating and 2.0 A continuous current support ≤15 W LED loads in SO-7 package.
Current Sense Reference	0.4 V typical V_CS-REF sets precise peak current threshold for constant-current control.
Startup Current	170 µA low start-up current minimizes auxiliary supply losses and enables direct AC-derived VCC startup.
Thermal Fold-Back Threshold	+140°C activation reduces output current linearly before OTP, preventing thermal runaway in enclosed fixtures.
Operating Junction Temp	−40°C to +150°C range supports deployment in high-ambient environments like streetlight housings.

Pinout & Package

AL1678-20BS7-13 is housed in a 7-pin SO-7 surface-mount package with exposed drain pad for thermal dissipation. Pin 7 (Drain) connects directly to the internal 500 V MOSFET's drain terminal; Pin 1 (OUT) is the source node; Pin 5 (CS) senses inductor current via external shunt resistor.

Pin/Terminal	Circuit Role	Design Meaning
1 OUT	Internal MOSFET source	Return path for LED current; connects to low-side of buck inductor and load cathode.
2 VCC	IC power supply	Accepts 8.5–16.2 V DC; powers internal circuitry after startup; clamped at 16.2 V.
3 ROVP	Output open-voltage sense	Monitors output voltage via resistor divider; triggers OVP when >0.46 V reference is exceeded.
4 GND	Signal and power ground	Common reference for CS, ROVP, LC, and internal logic; must be low-impedance return path.
5 CS	Current sense input	Compares sensed voltage across R_sense to 0.4 V reference to terminate t_ON.
6 LC	Line compensation	Adjusts current regulation vs. input voltage to maintain constant output current over 85–277 VAC.
7 Drain	Internal MOSFET drain	High-side switch node; connects to bulk capacitor positive and buck inductor input.

Key Features

Feature	Design Value
Valley-switching control	Reduces switching loss and EMI by turning on MOSFET at zero-current crossing in BCM.
Single-winding inductor support	Eliminates need for auxiliary winding, cutting BOM count and cost in non-isolated buck topologies.
Thermal fold-back + OTP	Gradual current reduction from +140°C and latched shutdown at +170°C prevent thermal damage in sealed enclosures.
Integrated protections	UVLO, LEB, open/short LED detection, and output OVP enable robust field operation without external supervision.
SO-7 RoHS/Green package	Lead-free, halogen-free, antimony-free construction meets global environmental compliance requirements.

Applications

Retrofit LED Lamps

High-Voltage DC-DC LED Driver

Use Scenario: Replacing incandescent or CFL bulbs in E26/E27 sockets with AC-powered LED modules.

IC Role / Device Role / Timing Role: Primary constant-current controller in non-isolated buck topology, regulating LED current directly from rectified AC.

Use Value: Enables <15 W output with ±3% current stability and built-in open-circuit protection to prevent capacitor overvoltage.

Use Scenario: Driving high-brightness LED strings in industrial signage or architectural lighting powered from 277 VAC building circuits.

IC Role / Device Role / Timing Role: High-voltage buck controller managing boundary conduction timing and MOSFET gate drive without optocoupler feedback.

Use Value: Supports 277 VAC input directly, eliminating step-down transformer and reducing system size/cost while maintaining EMI compliance.

General-Purpose Constant Current Source

Enclosed Outdoor LED Fixture

Use Scenario: Providing stable current to laser diodes, sensor bias networks, or analog front-ends requiring precision DC current.

IC Role / Device Role / Timing Role: Precision current regulator using internal 0.4 V reference and peak-current sensing for accurate setpoint control.

Use Value: Delivers ±3% current accuracy over temperature and line, with thermal fold-back preserving reliability under sustained load.

Use Scenario: Streetlight or parking lot fixture where ambient temperature exceeds 85°C and enclosure limits airflow.

IC Role / Device Role / Timing Role: Thermal-aware LED driver implementing adaptive current reduction above +140°C junction temperature.

Use Value: Prevents thermal runaway and extends lifetime by dynamically scaling output power before reaching +170°C latch point.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AL1678-10BS7-13	Lower 1.0 A MOSFET rating and 10 W max output power; identical pinout and control architecture.	Suitable for ≤10 W LED loads; reduced thermal stress but lower power ceiling.	Select when target output current is ≤180 mA and thermal margin is prioritized over wattage headroom.
AL1678-08BS7-13	0.8 A MOSFET, 8 W max output, same SO-7 footprint and functional block diagram.	Optimized for compact, low-power LED modules (<120 mA); not orderable per datasheet Note 11.	Not recommended for production due to development status; verify availability and qualification before design-in.

Compared with AL1678-10BS7-13 and AL1678-08BS7-13, the AL1678-20BS7-13 provides highest power capability (2.0 A/15 W) and thermal headroom in the same SO-7 package, making it optimal for retrofit lamps requiring full 240 mA output with robust thermal fold-back.

Availability

AL1678-20BS7-13 is available at Aetrix Electronics and suitable for retrofit LED lamps, high-voltage DC-DC LED drivers, and general-purpose constant current sources requiring stable component supply and long-term manufacturability planning.

Supply support for AL1678-20BS7-13 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 manufacturer of discrete semiconductors and analog ICs, specializing in power management, signal integrity, and LED lighting solutions.

The AL1678 series belongs to Diodes' AC-DC LED driver product line, designed specifically for cost-sensitive, non-isolated buck LED applications requiring high efficiency, tight current regulation, and comprehensive fault protection in compact packages.

FAQ

Is AL1678-20BS7-13 still in active production?

No - the datasheet explicitly states "OBSOLETE – PART DISCONTINUED" with no alternate part offered. Aetrix Electronics maintains limited legacy stock for design continuity and repair programs, but new designs should consider next-generation alternatives with active support.

What is the maximum output power achievable with AL1678-20BS7-13?

The datasheet specifies ≤15 W output power for AL1678-20B variants, limited by the 2.0 A MOSFET rating, SO-7 thermal resistance (190°C/W), and 0.65 W power dissipation at +50°C ambient. Higher power requires external heatsinking or forced-air cooling beyond standard PCB layout.

Can AL1678-20BS7-13 operate without an auxiliary winding?

Yes - it uses valley-switching detection and internal timing to derive VCC from the main inductor, eliminating the need for an auxiliary winding. VCC is supplied directly from the rectified AC bus through a resistor-capacitor network, enabling ultra-low-BOM-count designs.

How does the thermal fold-back function interact with over-temperature protection?

Thermal fold-back activates at +140°C junction temperature, linearly reducing output current to limit power dissipation. If temperature continues rising to +170°C, OTP triggers a latched shutdown. The device remains off until AC power is cycled - no automatic recovery occurs during thermal overload.

AL1678-20BS7-13 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width), 7 Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: AC DC Offline Switcher

Topology:: Step-Down (Buck)

Internal Switch(s):: Yes

Number of Outputs:: 1

Voltage - Supply (Min):: 8.5V

Voltage - Supply (Max):: 18V

Voltage - Output:: 15V ~ 35V

Current - Output / Channel:: 2A

Frequency:: 350kHz

Dimming:: No

Applications:: Lighting

Operating Temperature:: -40°C ~ 105°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 7-SO

AL1678-20BS7-13 FAQ

1.How can I place an order for AL1678-20BS7-13 through Aetrix?

Please submit a Request for Quotation (RFQ) for AL1678-20BS7-13 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 AL1678-20BS7-13 reliable?

The price and inventory of AL1678-20BS7-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AL1678-20BS7-13 is usually 5 days.

3.What payment methods are accepted for AL1678-20BS7-13?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AL1678-20BS7-13 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AL1678-20BS7-13?

AL1678-20BS7-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AL1678-20BS7-13 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 AL1678-20BS7-13?

For technical support, including AL1678-20BS7-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AL1678-20BS7-13 requirements.

6.How does Aetrix verify that AL1678-20BS7-13 is sourced from the original manufacturer or authorized distributors?

All AL1678-20BS7-13 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 AL1678-20BS7-13 meets industry standards.

7.What is the process for return or replacement of AL1678-20BS7-13?

All AL1678-20BS7-13 units undergo pre-shipment inspection (PSI). If there is an issue with AL1678-20BS7-13, 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 AL1678-20BS7-13 part is unused and in its original packaging.

Return procedure for AL1678-20BS7-13:

1.Submit a request within 90 days.

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

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