Diodes Incorporated AP1684MTR-G1

Overview

AP1684MTR-G1 from Diodes Incorporated is a high-performance AC/DC LED driver controller implementing boundary conduction mode (BCM) buck topology with pulse frequency modulation (PFM), driving external high-voltage bipolar junction transistors for non-dimmable LED lighting. It delivers ±2% output current accuracy, power factor >0.9, THD <30%, and up to 92% system efficiency while eliminating optocouplers, secondary feedback, and loop compensation circuitry. It targets GU10/E27 LED bulb and downlight applications requiring IEC 61000-3-2 compliance.

For engineers reviewing the AP1684MTR-G1 datasheet, AP1684MTR-G1 pinout, AP1684MTR-G1 application, or AP1684MTR-G1 equivalent, this controller offers verified valley-on switching, dynamic base drive control, integrated overvoltage/short-circuit/overtemperature protection, and SO-8 package compatibility - critical for cost-sensitive, EMI-constrained LED driver designs.

Technical Context

The AP1684 operates in boundary conduction mode using constant on-time (TONP) control with valley-sensing via the FB pin to minimize switching losses. Its PFM regulation achieves high power factor by shaping input current to follow the sinusoidal AC line voltage without active PFC circuitry.

It integrates a dedicated BJT gate driver (OUT pin), current sense comparator (CS pin), auxiliary winding feedback (FB pin), and internal reference (V_{CS_REF} = 1 V) for primary-side constant current regulation. Protection logic includes UVLO (18–20 V start-up, 5.5–7.5 V operating), VCC OVP (30–34 V), FB OVP (4.5–7.5 V), and thermal shutdown at +150 °C with +20 °C hysteresis.

Key Specifications

Pinout & Package

AP1684MTR-G1 is housed in an SO-8 package (6.20 × 4.00 × 1.25 mm, RoHS-compliant, halogen-free). Pin assignments are validated per Diodes DS36547 Rev. 4–3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1694AS-13 and BP5758D, the AP1684MTR-G1 uniquely balances low BOM cost, proven BCM-based PF correction, and SO-8 manufacturability - making it optimal for high-volume GU10/bulb applications where thermal pad integration is unnecessary and isolation is avoided.

Availability

AP1684MTR-G1 is available at Aetrix Electronics and suitable for LED bulb lamp, LED down light, and GU10 spotlight applications requiring stable component supply, RoHS/Green compliance, and SO-8 assembly compatibility.

Supply support for AP1684MTR-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, specializing in power management, signal integrity, and lighting solutions for industrial, consumer, and automotive markets.

The AP1684 belongs to Diodes' LED driver controller product line, designed specifically for cost-sensitive, non-dimmable AC/DC LED lighting with emphasis on high power factor, low THD, and minimal external component count.

FAQ

What is the recommended minimum value for the current sense resistor R8?

The minimum R8 value is determined by the maximum allowable peak current at CS pin: R8_min = V_{CS_CLAMP} / I_{PEAK_MAX}. With V_{CS_CLAMP} = 1.4 V and max CS pin current of 150 mA (per absolute ratings), R8_min ≈ 9.3 Ω. However, typical designs use 0.22–1.0 Ω to achieve 200–350 mA LED current while maintaining >100 mV noise margin above V_{CS_REF} = 1 V.

Does AP1684MTR-G1 support dimming functionality?

No, AP1684MTR-G1 does not support analog or PWM dimming. It is explicitly designed for non-dimmable LED lighting applications, as stated in its datasheet description and recommended applications table. The control architecture lacks dedicated dimming interface pins or internal circuitry for brightness adjustment - adding external dimming would require redesigning the entire feedback and timing structure.

How is valley-on switching implemented without a dedicated ZCD pin?

Valley-on switching is implemented by monitoring the FB pin voltage, which reflects the auxiliary winding voltage proportional to the BJT collector-emitter voltage. When the falling edge of a 0.1 V threshold is detected on FB, the IC waits 1 µs before initiating the next switching cycle - ensuring turn-on occurs near the voltage valley. This method eliminates the need for a separate ZCD pin while maintaining accurate valley detection across line and load variations.

What is the maximum allowable output power for AP1684MTR-G1 in SO-8 package?

Maximum continuous output power is limited by thermal dissipation: at TA = +50 °C, PD_max = 0.65 W with θ_JA = 160 °C/W. Accounting for internal power consumption (~15 mW) and driver losses, practical output power is capped at ~12 W for GU10/bulb applications. Higher power requires forced air cooling or package upgrade - Diodes explicitly recommends AP1694AS-13 for >15 W designs.