Diodes Incorporated APX824-40W5G-7

Overview

APX824-40W5G-7 from Diodes Incorporated is a fixed-threshold processor supervisory circuit with active-high reset output, 4.00V negative-going supply voltage detection threshold (V_TH−), 200ms typical reset delay (t_d), 1.6s watchdog timeout (t_tout), and SOT25-5 package. It monitors V_CC in microcontroller-based systems, asserts RESET during power-up below 1.1V, and supports manual reset via WDI transitions - used in industrial programmable controllers requiring reliable brownout protection.

For engineers reviewing the APX824-40W5G-7 datasheet, APX824-40W5G-7 pinout, APX824-40W5G-7 application, or APX824-40W5G-7 equivalent, key selection criteria include its 4.00V supervision threshold, active-high RESET logic, watchdog enable/disable via WDI connection, 30μA typical supply current, and -40°C to +85°C operating range - all critical for embedded system power sequencing and fault recovery design.

Technical Context

The APX824-40W5G-7 implements a precision bandgap-based voltage reference to set its 4.00V (±30mV) V_TH− threshold with 50mV hysteresis, ensuring stable release from reset during supply ramp-up. Its internal RC timer generates a fixed 200ms (140–280ms) delay after V_CC exceeds V_TH−, guaranteeing sufficient deassertion hold time for CPU initialization.

Watchdog functionality is triggered by any edge on WDI; failure to retrigger within 1.6s (1.12–2.4s) forces active-high RESET assertion for t_d, then auto-restarts the watchdog. The device requires no external components, features internal MR pull-up (60kΩ), and operates across 1.1V–5.5V V_CC with 30μA typical ICC at V_TH−+0.2V.

Key Specifications

Pinout & Package

SOT25-5 surface-mount package (3.0mm × 2.8mm × 1.1mm, JEDEC MO-203AA), RoHS-compliant matte tin plating, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with APX824-40W5G-7, the -44 variant offers higher threshold margin for noisy 5V rails, while MAX809SEUR+T sacrifices watchdog and output polarity flexibility for smaller size and lower cost in non-critical applications.

Availability

APX824-40W5G-7 is available at Aetrix Electronics and suitable for industrial automation, smart metering, and network infrastructure applications requiring stable component supply, long-term lifecycle support, and guaranteed green packaging compliance.

Supply support for APX824-40W5G-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 targets embedded system reliability - designed specifically for DSP, MCU, and MPU power-on initialization, brownout recovery, and firmware watchdog enforcement in harsh ambient conditions.

FAQ

What is the function of Pin 5 (NC) on the APX824-40W5G-7?

Pin 5 is a no-connect terminal - internally unconnected and electrically isolated. It must not be soldered to V_CC or GND. Per Diodes' recommended layout, it may be left floating or tied to GND for mechanical stability, but never to a voltage rail. This pin exists due to SOT25-5 package standardization across the APX823/APX824/APX825A family and carries no electrical function in the APX824 variant.

Can the watchdog timer be disabled without connecting WDI?

Yes - leaving WDI unconnected disables the watchdog function entirely. The device will still perform power-on reset and supply voltage supervision, but will not monitor WDI transitions or assert RESET due to watchdog timeout. No pull-up or pull-down is required on WDI for disable mode; the internal input structure ensures high-impedance behavior when unconnected.

Does APX824-40W5G-7 support operation at 2.5V supply voltage?

No - the APX824-40W5G-7 has a fixed 4.00V V_TH− threshold and is specified for use with 5V nominal systems. While its absolute maximum V_CC rating is 6.0V and recommended operating range starts at 1.1V, the 4.00V threshold means it will assert RESET continuously below ~4.0V and cannot supervise 2.5V or 3.3V rails. For those voltages, select APX824-29W5G-7 (2.93V) or APX824-31W5G-7 (3.08V).

Is the RESET output truly push-pull or open-drain?

The APX824-40W5G-7 RESET output is actively driven high and low - it is a true push-pull (totem-pole) output, not open-drain. Electrical characteristics confirm VOH ≥0.8×V_CC at -100μA and VOL ≤0.4V at 1mA, verifying bidirectional drive capability. This eliminates the need for an external pull-up resistor and allows direct interfacing with CMOS inputs requiring rail-to-rail logic levels.