onsemi NCP803SN293D2T1G Voltage Supervisor: Features and Application Circuit Design
Voltage supervisors, also known as voltage monitors or reset ICs, are fundamental components in modern electronic systems, ensuring controlled startup and reliable operation. The onsemi NCP803SN293D2T1G represents a highly integrated and precise solution in this category, designed to monitor power supply voltages and provide a reset signal to a microcontroller or processor until the system voltage has stabilized at a valid level.
Key Features of the NCP803SN293D2T1G
This voltage supervisor is packed with features that make it suitable for a wide array of applications, from consumer electronics to industrial systems.
1. Precision Voltage Monitoring: The core function of this IC is to monitor a VCC supply voltage. The specific part number NCP803SN293D2T1G is factory-programmed to have a precise threshold voltage of 2.93V. This high accuracy ensures the monitored system resets only when absolutely necessary, preventing erratic behavior.
2. Low Quiescent Current: A critical feature for battery-powered and portable devices is its ultra-low supply current. The device consumes a typical 3 µA of quiescent current, making it an excellent choice for power-sensitive applications where extending battery life is paramount.
3. Push-Pull Reset Output: The NCP803SN293D2T1G features a push-pull (active-low) reset output. Unlike open-drain outputs, this configuration does not require an external pull-up resistor, simplifying the board design and saving both space and component count. The output asserts low when VCC is below the threshold and remains asserted for a minimum period after VCC rises above it.
4. Built-in Hysteresis: The device incorporates built-in hysteresis, typically 1.5% of the threshold voltage. This feature prevents oscillation of the reset signal when the power supply voltage hovers near the trip point due to noise or slow voltage ramp-up/down, guaranteeing a clean and stable reset signal.
5. Small Package: It is offered in a space-saving SOT-23-3 package, which is ideal for high-density PCB layouts common in modern compact electronics.
Application Circuit Design
Implementing the NCP803SN293D2T1G in a circuit is remarkably straightforward, thanks to its minimal external component requirement. A typical application circuit for monitoring a microcontroller's power rail is shown below.
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Circuit Description and Design Considerations:
1. Power Supply Connection (VCC): Pin 2 (VCC) is connected directly to the power supply rail that requires monitoring (e.g., the 3.3V rail of a system). A decoupling capacitor (typically 100 nF) should be placed as close as possible to the VCC and GND pins of the IC to filter out high-frequency noise and ensure stable operation.
2. Ground Connection (GND): Pin 1 is connected to the system ground plane.
3. Reset Output (/RESET): Pin 3 is the active-low reset output. It is connected directly to the reset pin (often labeled /RST or /MR) of the microcontroller or processor. The push-pull output architecture means no external pull-up resistor is needed. The output will be held low when VCC is below the 2.93V threshold or during the reset timeout period after VCC becomes valid.
This simple 3-wire connection (VCC, GND, /RESET) provides a robust and reliable power-on reset (POR) function for the host processor. The fixed timeout period ensures the microcontroller remains in reset until the power supply and system clock are fully stable.
ICGOODFIND Summary
The onsemi NCP803SN293D2T1G is an exemplary voltage supervisor IC that offers a blend of high precision, ultra-low power consumption, and exceptional design simplicity. Its fixed threshold voltage of 2.93V makes it perfectly suited for monitoring common 3V and 3.3V system rails. The integrated push-pull output and minimal external component requirement allow for a compact and cost-effective solution, significantly enhancing the reliability of electronic systems without complicating the design process. It is an ideal choice for ensuring system integrity in portable, battery-operated, and space-constrained applications.
Keywords:
Voltage Supervisor
Reset IC
Power Management
Low Quiescent Current
Application Circuit
