## Overview of the R3111Q552B The **R3111Q552B** is a high-accuracy, low-power **Voltage Detector IC** (often referred to as a Reset IC) manufactured by **Nisshinbo Micro Devices** (formerly Ricoh Electronic Devices). This component is primarily used to monitor power supply voltages and provide a reset signal to microprocessors or other logic circuits when the voltage drops below a specific threshold. --- ### Key Specifications and Technical Details The nomenclature "552B" within the part number defines its specific electrical characteristics: | Feature | Specification | | :--- | :--- | | **Detector Threshold ($V_{DET}$)** | 5.5V | | **Output Type** | N-channel Open Drain | | **Active Level** | Low (Reset signal is Low when $V_{DD} < V_{DET}$) | | **Supply Voltage Range** | 0.7V to 10.0V | | **Supply Current ($I_{SS}$)** | Typ. 0.8 $\mu$A ($V_{DD}$ = 7.0V) | | **Detector Threshold Accuracy** | ±2.0% | | **Package Type** | SC-82AB (4-pin small surface mount) | | **Operating Temperature** | -40°C to +85°C | --- ### Internal Functional Blocks The R3111 series consists of several internal stages to ensure precise voltage monitoring: 1. **Reference Voltage Source:** Provides a stable internal voltage to compare against the input. 2. **Voltage Comparator:** Compares the $V_{DD}$ pin voltage against the internal reference. 3. **Resistor Net:** A high-impedance divider that sets the 5.5V detection threshold. 4. **Output Driver:** An N-channel MOSFET (Open Drain) that pulls the signal to ground when a brown-out occurs. --- ### Pin Configuration (SC-82AB) | Pin No. | Symbol | Description | | :--- | :--- | :--- | | 1 | **OUT** | Output Pin (N-ch Open Drain) | | 2 | **VDD** | Input Voltage / Power Supply | | 3 | **NC** | No Connection | | 4 | **VSS** | Ground Pin | --- ### Application Circuitry Since the R3111Q552B is an **Open Drain** type, it requires an external **pull-up resistor** to function correctly. This allows the IC to interface with different logic levels (e.g., pulling up to 3.3V even if the monitored line is 5.5V). ```markdown Typical Connection: [Power Rail 5.5V] ----+---- [VDD Pin] | [Resistor R] | [Logic Rail 3.3V] ----+---- [OUT Pin] ----> [MCU Reset Pin] | [GND] --------- [VSS Pin] ``` --- ### Core Advantages * **Ultra-Low Power Consumption:** At 0.8 $\mu$A, it is ideal for battery-powered devices where energy efficiency is critical. * **Small Footprint:** The SC-82AB package is extremely small, saving PCB real estate in handheld electronics. * **High Stability:** Built-in hysteresis prevents "chatter" or false resetting when the supply voltage fluctuates near the threshold.