Diodes Incorporated APX803S-31SA-7

Overview

APX803S-31SA-7 from Diodes Incorporated is a 3-pin SOT23 open-drain microprocessor reset supervisor IC with 3.08V ±0.05V reset threshold, 240ms minimum reset timeout, 10µA typical supply current, and guaranteed operation down to VCC = 1V. It monitors 3.3V digital power rails in embedded controllers and portable systems to prevent erroneous code execution during power-up, brownout, or supply glitches.

For engineers reviewing the APX803S-31SA-7 datasheet, APX803S-31SA-7 pinout, APX803S-31SA-7 application, or APX803S-31SA-7 equivalent, key selection criteria include precise 3.08V threshold tolerance, fixed 240ms active-low reset pulse duration, open-drain output compatibility with bidirectional µP reset pins, and validated operation across –40°C to +85°C ambient temperature.

Technical Context

The APX803S-31SA-7 implements a precision bandgap-based voltage comparator with 30ppm/°C tempco to detect VCC falling below 3.08V, triggering an open-drain RESET low signal. Its internal timer initiates only after VCC rises above threshold and holds RESET asserted for ≥240ms - independent of VCC slew rate up to 100V/µs.

Designed for direct integration into 3.3V systems, it requires no external components, draws ≤15µA over temperature, and maintains valid logic state (RESET = low) for VCC ≥1V. The SOT23-SA package supports standard PCB layout with GND–VCC–RESET pin order and 232°C/W θJA thermal resistance.

Key Specifications

Pinout & Package

SOT23-3 (SA package) with 2.9mm × 1.3mm footprint, 0.95mm height, and gull-wing leads. Thermal resistance θJA = 232°C/W enables operation at full rating in compact PCB layouts without heatsinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor reset supervision applications.

Compared with APX803S-31SA-7, the APX809S-31SA-7 simplifies BOM by eliminating the pull-up resistor but sacrifices bus-sharing flexibility, while the MAX809TRD29+T reduces cost at the expense of reset timing margin and power efficiency in battery-critical applications.

Availability

APX803S-31SA-7 is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for APX803S-31SA-7 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for industrial, computing, and automotive markets.

The APX803S series belongs to Diodes' precision voltage supervisor product line, engineered specifically for deterministic reset behavior in resource-constrained embedded systems where supply rail stability directly impacts firmware integrity and system safety.

FAQ

What is the exact reset threshold voltage for APX803S-31SA-7 at room temperature?

The APX803S-31SA-7 has a nominal reset threshold of 3.08V at +25°C, with guaranteed limits of 3.04V (min) and 3.13V (max) across production lots. This value is factory-trimmed using laser calibration and verified per DS39161 Rev. 2-2, Table 1, ensuring consistent detection of 3.3V rail collapse before microprocessor malfunction.

Does APX803S-31SA-7 require an external pull-up resistor on the RESET pin?

Yes - the APX803S-31SA-7 features an open-drain RESET output that must be pulled up to a valid logic-high voltage (e.g., µP I/O rail) via an external resistor. Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements; no internal pull-up exists, and omission will result in floating RESET states.

Can APX803S-31SA-7 supervise a 5V supply rail?

No - the APX803S-31SA-7 is specifically trimmed for 3.08V threshold and optimized for 3.3V systems. For 5V supervision, Diodes offers the APX803S-40SA-7 (4.00V threshold) or APX803S-44SA-7 (4.38V threshold), both sharing identical timing, current, and package characteristics but differing only in factory-set voltage reference.

How does the 240ms reset timeout behave during repeated brownout events?

Each time VCC falls below the 3.08V threshold, the internal timer resets and forces RESET low immediately. The 240ms timeout begins anew only after VCC rises above threshold and remains stable; this ensures continuous reset assertion during sustained brownouts and prevents premature release during voltage ripple, as confirmed in the Functional Description section of DS39161.