PROCESSOR SUPERVISORY CIRCUITS # Technical Documentation: APX82329W5G7 - Ultra-Low Power System Supervisor
Manufacturer : DIODES Incorporated
Document Version : 1.0
Last Updated : October 2023
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## 1. Application Scenarios
### 1.1 Typical Use Cases
The APX82329W5G7 is a CMOS-based system supervisor circuit designed primarily for microprocessor/microcontroller monitoring in battery-powered and power-sensitive applications. Its core function is to assert a reset signal to the host processor when the supply voltage falls below a predefined threshold, ensuring controlled system initialization and preventing data corruption during power anomalies.
Primary use cases include:
- Power-On Reset (POR) Generation : Provides a clean, timed reset pulse (typically 140ms minimum) upon initial power-up, allowing the system voltage and clock to stabilize before the processor begins execution.
- Brown-Out Detection (BOD) : Continuously monitors the VCC supply. If the voltage dips below the factory-set reset threshold (e.g., 2.93V, 3.08V variants), it immediately asserts an active-low reset (`RESET` output) and holds it for a minimum period after VCC recovers, ensuring the processor remains in a safe state.
- Manual Reset Control : Incorporates a manual reset input pin (`MR`), allowing a user or external logic signal to force a system reset, enhancing system debug and control capabilities.
### 1.2 Industry Applications
Due to its ultra-low supply current (typically 1.0 µA) and small SOT-25 package, the APX82329W5G7 is ideal for portable, battery-operated, and always-on devices.
- Consumer Electronics : Smartwatches, fitness trackers, wireless earbuds, remote controls, and digital cameras. Its low quiescent current is critical for extending battery life.
- Internet of Things (IoT) : Sensor nodes, smart home devices (thermostats, door/window sensors), and asset trackers where devices spend most of their time in sleep mode and require reliable wake-up/reset functionality.
- Industrial Control & Automation : Handheld meters, portable data loggers, and low-power sensor interfaces in 3.3V or 3.0V systems.
- Medical Devices : Hearing aids, portable monitors, and other wearable medical electronics where size, reliability, and power efficiency are paramount.
- Embedded Systems : General-purpose microcontroller (e.g., ARM Cortex-M, PIC, AVR) boards, system-on-modules (SoMs), and development kits requiring a simple, reliable reset circuit.
### 1.3 Practical Advantages and Limitations
Advantages:
- Extremely Low Power Consumption : Typical `Icc` of 1.0 µA minimizes battery drain, making it suitable for always-on applications.
- High Accuracy : Reset threshold voltage accuracy is typically ±1.5%, ensuring reliable operation across temperature and process variations.
- Small Form Factor : SOT-25 package (5-pin) saves valuable PCB space in compact designs.
- Simplified Design : Integrates the timing capacitor internally, eliminating an external component and reducing BOM cost and board area.
- Wide Operating Voltage Range : Can operate from 1.0V to 5.5V, monitoring common supply rails like 3.3V, 3.0V, and 2.5V (depending on ordered variant).
- Push-Pull RESET Output : Does not require an external pull-up resistor, simplifying layout.
Limitations:
- Fixed Threshold and Timeout : The reset threshold voltage (`Vrst`) and reset timeout period are factory-set and cannot be adjusted by the user. Designers must select the appropriate part number variant (e.g., APX823-29 for
