Diodes Incorporated AP2821KTR-G1

Overview

AP2821KTR-G1 from Diodes Incorporated is a discontinued high-side power distribution switch featuring an integrated n-channel MOSFET with 120 mΩ R_DS(ON) at 5.0 V, TTL-compatible enable input, soft-start, foldback current limiting (2 A), and undervoltage lockout (UVLO) at 2.5 V nominal - designed for USB-compliant hot-plug power control in portable computing and hub applications.

For engineers reviewing the AP2821KTR-G1 datasheet, AP2821KTR-G1 pinout, AP2821KTR-G1 application, or AP2821KTR-G1 equivalent, key selection criteria include its 2.7–5.5 V operating range, <1 µA shutdown current, reverse-current blocking during disable, and SOT-23-5 thermal performance (θ_JA = 235 °C/W).

Technical Context

The AP2821 implements a charge-pump gate driver to fully enhance the internal n-channel MOSFET across its 2.7–5.5 V input range, enabling low R_DS(ON) without external bias. Its UVLO circuit ensures turn-on only above 2.5 V with 0.2 V hysteresis, preventing erratic switching during brown-out conditions.

Overcurrent protection uses foldback limiting: output current drops to ~1.5 A under short-circuit while maintaining thermal shutdown at +145 °C with +20 °C hysteresis. A dedicated 100–250 Ω pull-low resistor discharges C_OUT when EN is deasserted, eliminating reverse current flow.

Key Specifications

Pinout & Package

SOT-23-5 package: 2.82 × 1.50 × 1.10 mm body, 0.95 mm pin pitch, thermally enhanced pad layout per Diodes' recommended footprint (E2 = 3.60 mm, Y = 1.00 mm).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side load switch applications.

Compared with AP2821KTR-G1, AP2822KTR-G1 offers dual-channel integration at minor R_DS(ON) penalty, while TPS22965DSGT delivers superior conduction loss and current handling but forfeits native reverse-current blocking - requiring design-level trade-offs in safety and component count.

Availability

AP2821KTR-G1 is available at Aetrix Electronics and suitable for USB power management, hot-plug power supplies, and notebook motherboard power sequencing requiring stable component supply despite its obsolete status - supported via legacy inventory and cross-reference assistance.

Supply support for AP2821KTR-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 protection solutions for consumer, industrial, and automotive markets.

The AP2821 belongs to Diodes' high-side load switch product line, engineered specifically for USB-compliant hot-plug power control with integrated protection features and minimal external components.

FAQ

Is AP2821KTR-G1 still in production?

No - Diodes Incorporated has officially discontinued the AP2821KTR-G1. It is marked "OBSOLETE – PART DISCONTINUED" in the latest datasheet (Rev. 4-4, June 2025). Aetrix Electronics maintains limited legacy stock and supports transition to validated alternatives such as AP2822KTR-G1 or TPS22965DSGT with full parametric and footprint guidance.

What is the purpose of the dual VIN pins (4 and 5) in SOT-23-5?

Pins 4 and 5 are internally bonded to the same VIN node and serve as parallel input connections to reduce trace inductance and improve current sharing. This dual-pin layout minimizes voltage drop and thermal stress during 2 A continuous operation, especially critical in compact USB port designs with tight PCB routing constraints.

Does AP2821KTR-G1 support reverse-voltage protection?

Yes - it provides active reverse-current blocking when disabled: the internal 100–250 Ω pull-low resistor discharges the output capacitor, ensuring VOUT cannot back-drive VIN. This eliminates need for external Schottky diodes in USB VBUS paths and complies with USB specification requirements for power directionality.

Can AP2821KTR-G1 operate from a 3.3 V supply?

Yes - its 2.7–5.5 V operating range includes 3.3 V systems. At 3.3 V input, R_DS(ON) increases to ~180 mΩ (per datasheet curves), resulting in ~0.45 V drop at 2.5 A. This remains within acceptable limits for non-USB 3.0 applications like internal 3.3 V rail switching where voltage margin allows.