Diodes Incorporated AP1686K6TR-G1

Overview

AP1686K6TR-G1 from Diodes Incorporated is a primary-side regulation (PSR) AC/DC LED controller IC implementing Pulse Frequency Modulation (PFM) in discontinuous conduction mode (DCM) flyback topology. It delivers accurate constant voltage (3.974 V FB threshold) and constant current regulation without optocoupler or secondary-side feedback, achieves ≤30 mW no-load input power, and drives external bipolar junction transistors (BJTs) with 30 mA source current at the OUT pin. It is used in compact, low-cost offline LED drivers for residential and commercial lighting.

For engineers reviewing the AP1686K6TR-G1 datasheet, AP1686K6TR-G1 pinout, AP1686K6TR-G1 application, or AP1686K6TR-G1 equivalent, key selection considerations include its BJT gate drive capability, 500 mV current sense threshold, line compensation transconductance (1.43 μs), SOT-23-6 thermal resistance (200 °C/W), and absence of alternate recommended parts per manufacturer notice.

Technical Context

The AP1686K6TR-G1 integrates PFM-based timing control with built-in leading-edge blanking (475 ns typ), peak current sensing (500 mV threshold), and dual-loop CV/CC regulation via FB and CS pins. Its internal bias regulator powers the IC from VCC (3.5–4.5 V min operating), while the OUT pin provides active BJT base drive and fast sinking during turn-off.

Line compensation is implemented through proportional current sourcing from the CS pin during BJT conduction, enabling tight CC accuracy across universal AC input. Protection functions include over-voltage (7.5 V FB OVP), short-circuit, open-circuit, and UVLO (15.5 V startup threshold) with thermal shutdown at 150 °C junction temperature.

Key Specifications

Pinout & Package

The AP1686K6TR-G1 is housed in a thermally enhanced SOT-23-6 surface-mount package (2.82 × 2.65 × 1.45 mm), with pin 1 marked and leads RoHS-compliant (G1 suffix). The package supports reflow soldering up to 300 °C for 10 seconds.

Key Features

Applications

Availability

AP1686K6TR-G1 is available at Aetrix Electronics and suitable for residential LED bulbs, commercial downlights, and LED tube drivers requiring stable component supply and legacy design continuity.

Supply support for AP1686K6TR-G1 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and the Americas.

The AP1686 belongs to Diodes' AC/DC LED controller product line, designed specifically for cost-sensitive, low-power offline LED lighting applications where PSR simplifies isolation and reduces system-level BOM count.

FAQ

Is AP1686K6TR-G1 suitable for new designs?

No - Diodes Incorporated explicitly marks AP1686 as "NOT RECOMMENDED FOR NEW DESIGN" in the official datasheet (DS40909 Rev. 1-3, April 2018). It has no manufacturer-recommended alternate part. Designers should evaluate newer PSR controllers such as AP3765 or DIODES' AP169x series for new projects requiring long-term supply assurance and updated features.

What external transistor types are compatible with AP1686K6TR-G1?

The AP1686K6TR-G1 is optimized for NPN bipolar junction transistors (BJTs), not MOSFETs. Its OUT pin delivers 30 mA source current and 5 Ω sink resistance, matching typical BJT base drive requirements. Compatible devices include MMBT4401, DXT75500, or similar medium-speed, 500–800 mA Ic-rated NPN transistors with VCEO ≥ 400 V.

How does line compensation work on the CS pin?

During BJT conduction, the CS pin sources a current proportional to instantaneous line voltage. This current flows into the CS-to-ground sense resistor, generating a line-compensated voltage that offsets the current-sense threshold. As a result, output current remains stable across 90–264 VAC input without secondary feedback or digital calibration.

What is the maximum ambient temperature for reliable operation?

The AP1686K6TR-G1 specifies an operating junction temperature up to +150 °C and storage range from –65 °C to +150 °C. In practice, with SOT-23-6's θJA = 200 °C/W, sustained operation above +85 °C ambient requires ≥2 cm² of 2-oz copper pour under the package and minimal power dissipation (<150 mW) to avoid thermal shutdown.