The **R5105-R** refers to a high-precision voltage detector IC with a watchdog timer, typically manufactured by **Nisshinbo Micro Devices (formerly Ricoh Electronic Devices)**. It is widely used in automotive and industrial applications to monitor system power supply and processor operation. --- ## 1. Key Component Specifications The R5105-R is part of the R5105 series, designed for high-reliability systems requiring a window watchdog timer and voltage monitoring in a single package. | Feature | Specification | | :--- | :--- | | **Input Voltage Range** | 0.9V to 6.0V | | **Supply Current** | Typ. 11 µA | | **Watchdog Timer Type** | Window Watchdog (detects both fast and slow pulses) | | **Detector Threshold** | 1.6V to 5.0V (set internally in 0.1V steps) | | **Output Type** | N-ch Open Drain | | **Operating Temperature** | -40°C to 125°C (Automotive Grade) | | **Package Options** | SSOP-8G / SOT-23-6 | --- ## 2. Core Functional Blocks The device integrates three primary functions to ensure system "health": ### A. Voltage Detector (Reset Function) It monitors the VDD pin. If the voltage drops below the set threshold, the `RESETB` pin goes **LOW**. This prevents the microcontroller (MCU) from operating under unstable power conditions. ### B. Window Watchdog Timer (WDT) Unlike standard watchdogs that only check if an MCU has "frozen," a **Window Watchdog** checks if the MCU is sending pulses too slowly *or* too quickly. - **Open Window:** The MCU must send a clear signal during this period. - **Closed Window:** If the MCU sends a signal too early, it is treated as a software error, and the chip triggers a reset. ### C. Reset Delay Circuit The R5105-R includes an internal circuit to hold the reset signal for a specific duration (Reset Hold Time) after power stabilizes, ensuring the MCU initializes correctly. --- ## 3. Application Circuit Example The following is a conceptual representation of how the R5105-R interfaces with a Microcontroller. ```mermaid graph LR VDD[Power Supply] --> R5105[R5105-R] R5105 -- RESETB --> MCU_Reset[MCU Reset Pin] MCU_Pulse[MCU GPIO] -- WD_Signal --> R5105 ``` --- ## 4. Part Number Suffix Logic (The "-R") In Nisshinbo/Ricoh nomenclature, the suffixes denote specific packaging and environmental standards: * **-R:** Generally indicates the **Taping Direction** (Reel) for automated surface mount assembly. * **Quality Grade:** Often associated with "Automotive" or "Industrial" reliability testing (AEC-Q100 compliance).