onsemi NCP303LSN12T1

Overview

NCP303LSN12T1 from onsemi is an ultra-low-current voltage detector IC with programmable delay, designed as a reset controller for portable microprocessor systems. It features a 1.2 V ±2.0% undervoltage detection threshold, 0.5 µA typical quiescent current, open-drain N-channel active-low reset output, and operates from 0.8 V to 10 V supply. It is used in battery-powered embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the NCP303LSN12T1 datasheet, pinout, applications, or equivalent options, key selection criteria include its precise 1.2 V detection threshold, externally programmable delay via capacitor, −40°C to +125°C operating range (for 1.2 V variant), and compatibility with low-voltage microcontrollers and PMICs in space-constrained portable designs.

Technical Context

The NCP303LSN12T1 integrates a precision voltage comparator with hysteresis and an internal time-delay generator controlled by an external capacitor on Pin 5 (CD). Its detection circuit triggers when input voltage falls below 1.176 V (min) and releases above 1.224 V (max), ensuring noise immunity during power transitions.

It uses an open-drain N-channel output (Pin 1) that sinks up to 3.5 mA at V_OUT = 0.5 V and V_IN = 1.5 V, enabling flexible pull-up configuration. The CD pin provides a 1.0–2.0 MΩ internal pull-up resistance and a 0.67 V (typ) threshold for timing capacitor charging control.

Key Specifications

Pinout & Package

Package: Thin SOT-23-5 (TSOP-5/SC59-5), case 483 - 5-pin surface-mount package with 0.95 mm pitch and 2.9 mm × 1.6 mm footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage detector applications.

Compared with TLV809KDBZR and MAX809SEUR+T, the NCP303LSN12T1 uniquely delivers 1.2 V precision detection, programmable delay, and sub-µA operation in a 5-pin package-enabling robust, low-power reset control where timing flexibility and voltage accuracy are mandatory.

Availability

NCP303LSN12T1 is available at Aetrix Electronics and suitable for microprocessor reset, low-battery detection, and power-fail indicator applications requiring stable component supply across automotive, industrial, and portable electronics programs.

Supply support for NCP303LSN12T1 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

onsemi is a global semiconductor supplier delivering energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The NCP303 series belongs to onsemi's precision voltage detector product line, engineered specifically for ultra-low-power reset control in battery-sensitive portable and embedded systems requiring high accuracy and thermal stability.

FAQ

What is the exact detection threshold voltage of the NCP303LSN12T1?

The NCP303LSN12T1 has a guaranteed detection threshold of 1.176 V (minimum), 1.200 V (typical), and 1.224 V (maximum) at Pin 2 when input voltage is decreasing. This ±2.0% tolerance is specified over −40°C to +125°C for the 1.2 V variant, and hysteresis adds 0.036–0.084 V to prevent oscillation during marginal supply conditions. The NCP303LSN12T1 uses an internal bandgap reference for stable performance across temperature and supply variations.

How is the reset delay time programmed on the NCP303LSN12T1?

The reset delay time on the NCP303LSN12T1 is programmed using an external capacitor connected between Pin 4 (CD) and GND. The internal 1.0 MΩ (typical) pull-up resistance charges the capacitor, and the delay is determined by the time required for the CD pin voltage to reach its threshold (~0.67 V). For example, a 100 nF capacitor yields ~100 ms t_D2 delay at 25°C. The NCP303LSN12T1 datasheet provides curves mapping capacitance to t_D1 (seconds) and t_D2 (milliseconds) across temperature.

What is the maximum sink current capability of the NCP303LSN12T1 reset output?

The NCP303LSN12T1 open-drain reset output (Pin 1) can sink up to 3.5 mA when V_OUT = 0.5 V and V_IN = 1.5 V, per electrical characteristics table on page 10 of the datasheet. At lower voltages (e.g., V_OUT = 0.05 V), it sinks 0.14 mA minimum. This drive strength supports standard CMOS reset inputs and allows use with pull-up resistors down to ~10 kΩ while maintaining valid logic-low levels. The NCP303LSN12T1 does not source current - it is strictly open-drain active-low.

Is the NCP303LSN12T1 compatible with 1.8 V or 3.3 V microcontroller reset inputs?

Yes - the NCP303LSN12T1 is fully compatible with 1.8 V and 3.3 V microcontroller reset inputs because its open-drain output allows external pull-up to any logic rail. When used with a 3.3 V pull-up, the reset signal swings from 0 V (asserted) to 3.3 V (deasserted); with 1.8 V pull-up, it swings 0 V to 1.8 V. The NCP303LSN12T1 itself operates from 0.8 V to 10 V, so it can monitor either rail directly. No level-shifting circuitry is needed.

Does the NCP303LSN12T1 require a bypass capacitor on its input pin?

While not explicitly mandated in the datasheet, a 0.1 µF ceramic bypass capacitor placed as close as possible to Pin 2 (Input) and Pin 3 (GND) is strongly recommended for the NCP303LSN12T1. This stabilizes the sensed voltage during fast transients and reduces noise-induced false triggering, especially in noisy DC-DC converter environments. The NCP303LSN12T1's internal hysteresis helps but does not eliminate the need for local filtering - good layout practice ensures reliable operation across EMI-prone applications.