Microchip Technology HV9921N3-G

Overview

HV9921N3-G from Microchip Technology is a 3-pin switch-mode LED lamp driver IC with integrated 475V power MOSFET, fixed off-time (10.5 μs) PWM control, and internally set 20 mA constant output current. It operates directly from universal 85–264 VAC input without auxiliary winding or optocoupler, enabling compact, low-cost LED lighting solutions for decorative and low-power fixtures.

For engineers reviewing the HV9921N3-G datasheet, HV9921N3-G pinout, HV9921N3-G application, or HV9921N3-G equivalent, key selection criteria include its TO-92 package thermal limits (740 mW @ 25°C), 475 V drain breakdown, 7.5 V VDD regulator, 5.0 V UVLO threshold, and compatibility with triac dimmers in AC-fed LED lamps.

Technical Context

The HV9921N3-G implements a peak-current-controlled, fixed off-time buck converter operating in continuous conduction mode (CCM). Its internal 475 V MOSFET switches at variable frequency (determined by input voltage, LED string voltage, and 10.5 μs off-time), while the current sense comparator triggers turn-off when sensed drain current reaches 18.5–25.5 mA.

It integrates a high-voltage linear regulator that derives 7.5 V VDD from the DRAIN pin (20–400 V range), with 5.0 V under-voltage lockout and 200 mV hysteresis. Leading-edge blanking (300 ns) prevents false triggering from parasitic spikes during MOSFET turn-on.

Key Specifications

Pinout & Package

HV9921N3-G is supplied in a Pb-free, ROHS-compliant 3-lead TO-92 package (package code N3), optimized for through-hole mounting and cost-sensitive lighting modules. Thermal resistance θ_JA is 132°C/W on standard FR-4 PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AL8861SP-13 and BP5758D, HV9921N3-G uniquely combines universal AC input capability, fixed 20 mA current, TO-92 packaging, and self-powered operation-making it optimal for cost-sensitive, low-power, transformerless LED lamps where minimal bill-of-materials and board area are critical.

Availability

HV9921N3-G is available at Aetrix Electronics and suitable for decorative lighting, low-power LED fixtures, and AC-powered night lights requiring stable component supply, long-term lifecycle support, and ROHS-compliant packaging.

Supply support for HV9921N3-G 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

Microchip Technology is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and power management ICs, with ISO/TS-16949:2009 certification across wafer fabrication and design facilities.

HV9921N3-G belongs to Microchip's HV99xx family of single-stage, off-line LED drivers designed specifically for cost-optimized, transformerless AC-to-LED lighting solutions targeting decorative and indicator applications.

FAQ

What is the maximum input voltage the HV9921N3-G can handle?

HV9921N3-G supports input voltages up to 400 VDC at the DRAIN pin, corresponding to rectified universal AC input (85–264 VAC → ~373 VDC peak). Its 475 V drain breakdown voltage provides 75 V safety margin, allowing reliable operation even with line surges and ripple.

Does HV9921N3-G require an external current-setting resistor?

No, HV9921N3-G does not require an external current-setting resistor. Its output current is internally fixed at 20 mA via a precision current sense comparator with a threshold of 18.5–25.5 mA, eliminating calibration components and reducing BOM count.

Can HV9921N3-G be used with triac dimmers?

Yes, HV9921N3-G is explicitly designed for compatibility with leading-edge triac dimmers. Its fixed off-time control and internal blanking ensure stable dimming performance without external synchronization or snubber circuits across the full 85–264 VAC range.

What is the purpose of the VDD pin on HV9921N3-G?

The VDD pin on HV9921N3-G supplies regulated 7.5 V power to all internal control circuits. It is fed by an integrated high-voltage linear regulator drawing from the DRAIN pin, eliminating the need for an auxiliary winding or external bias supply in transformerless designs.

How does the HV9921N3-G manage thermal performance in TO-92 packaging?

HV9921N3-G is rated for 740 mW power dissipation at +25°C in its TO-92 package (θ_JA = 132°C/W). Effective thermal management requires a dedicated copper pour connected to the GND pin as a heatsink, minimized switching loop area, and avoidance of enclosed plastic housings above 60°C ambient.