Diodes Incorporated APX824-44W5G-7

Overview

APX824-44W5G-7 from Diodes Incorporated is a fixed-threshold processor supervisory circuit with active-high RESET output, 4.38 V negative-going supply voltage detection threshold (V_TH-), 200 ms reset delay time (t_d), and integrated watchdog timer (t_tout = 1.6 s typ). It operates across 1.1 V to 5.5 V supply range and supports DSP/microcontroller power-on initialization in industrial control and portable equipment.

For engineers reviewing the APX824-44W5G-7 datasheet, APX824-44W5G-7 pinout, APX824-44W5G-7 application, or APX824-44W5G-7 equivalent, key selection criteria include its SOT25 package, active-high reset assertion, 4.38 V supervision level, watchdog timeout stability over -40°C to +85°C, and compatibility with 3.3 V/5 V systems requiring reliable brownout recovery.

Technical Context

The APX824-44W5G-7 implements a precision bandgap-based voltage reference for V_TH- detection at 4.38 V (±30 mV over temperature), with 50 mV hysteresis to prevent chatter during supply ramping. Its internal RC timer generates a fixed 200 ms (typ) reset pulse after V_CC exceeds V_TH-, independent of external components.

Watchdog functionality responds to edge transitions on WDI with a 1.6 s timeout window; leaving WDI unconnected disables this feature. The device asserts active-high RESET when V_CC falls below V_TH- or when triggered by power-up sequencing, ensuring deterministic system initialization without software dependency.

Key Specifications

Pinout & Package

SOT25 package: 5-pin, small-outline transistor outline with gull-wing leads; 3.0 mm × 1.6 mm body, 0.95 mm pitch, JEDEC MO-178 compliant; RoHS-compliant matte tin plating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar processor supervision applications.

Compared with APX824-40W5G-7 and APX824-46W5G-7, the APX824-44W5G-7 offers optimal balance for standard 5 V systems: it triggers reset before critical logic voltage collapse (4.38 V) yet avoids nuisance resets from typical 5 V ripple (±5%), making it ideal for general-purpose industrial 5 V applications.

Availability

APX824-44W5G-7 is available at Aetrix Electronics and suitable for industrial automation, portable medical instrumentation, and wireless sensor gateway designs requiring stable component supply and long-term manufacturability.

Supply support for APX824-44W5G-7 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 high-reliability power management, signal integrity, and protection solutions for industrial and consumer markets.

The APX82x family belongs to Diodes' processor supervisory product line, engineered specifically for deterministic power-on reset and watchdog supervision in resource-constrained embedded systems operating across extended temperature ranges.

FAQ

What is the function of Pin 5 (NC) on the APX824-44W5G-7?

Pin 5 is a no-connect terminal with no internal connection. It must remain unconnected or be tied to ground per Diodes' recommended PCB layout guidelines to avoid parasitic coupling. This pin exists for mechanical symmetry in the SOT25 package and does not affect electrical performance or timing behavior.

Can the watchdog timer be disabled without modifying the PCB layout?

Yes - the watchdog timer is automatically disabled when the WDI pin is left unconnected (floating). No pull-up or pull-down resistor is required. This hardware-based disable method ensures full watchdog deactivation without firmware changes or additional components, simplifying qualification for applications that do not require runtime fault detection.

Does APX824-44W5G-7 support 3.3 V systems?

No - the 4.38 V threshold is optimized for 5 V rails. For 3.3 V systems, Diodes recommends APX824-29W5G-7 (2.93 V threshold) or APX824-31W5G-7 (3.08 V threshold). Using APX824-44W5G-7 on 3.3 V will result in permanent RESET assertion since V_CC never reaches V_TH-, preventing system startup.

How does the 50 mV hysteresis improve system reliability?

The 50 mV hysteresis prevents oscillatory reset behavior during slow or noisy supply ramps near V_TH-. When V_CC rises above 4.38 V, RESET deasserts; it only reasserts if V_CC falls to 4.33 V or lower. This gap eliminates false resets caused by supply ripple, transient noise, or thermal drift, ensuring single, clean reset pulses during power transitions.