Diodes Incorporated PT8A3231PEX

Overview

PT8A3231PEX from Pericom Semiconductor is a mixed-signal CMOS heating controller IC for automatic temperature regulation in 120V/240V appliances, featuring dual-voltage operation, NTC-based thermal sensing, NTC open-circuit protection, 1-hour auto-off timer (at 60 Hz), and direct SCR gate drive. It operates across –20°C to +85°C ambient and supports 8-pin DIP packaging.

For engineers reviewing the PT8A3231PEX datasheet, PT8A3231PEX pinout, PT8A3231PEX application, or PT8A3231PEX equivalent, key selection considerations include its integrated 2-bit ADC for NTC voltage sampling, CLK-synchronized SCR triggering, LED indicator logic with flash modes, and dual-key control interface for hair curlers and similar portable heating devices.

Technical Context

The PT8A3231PEX implements a state-machine-based thermal control architecture synchronized to AC line frequency via its CLK input (50/60 Hz). It samples NTC voltage at NTC1 using an internal 2-bit ADC referenced to VDD, comparing against three thresholds (VNTC0–VNTC2) to determine heating duty cycle and LED behavior.

Its GATE output drives an external SCR directly with active-high logic and up to 2.5 mA sink current; ON/OFF pins support two-button control with bidirectional I/O capability; NTC2 provides open-detection feedback; and the auto-off timer counts 216,000 clock cycles (≈1.2 h @50 Hz, ≈1 h @60 Hz) before disabling GATE.

Key Specifications

Pinout & Package

PT8A3231PEX is supplied in Pb-free DIP-8 package (JEDEC MS-001D/BA), with 0.3 inch body width, 9.0–9.4 mm length, and 6.2–6.6 mm width. Pin 1 is marked by notch or dot.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar heating controller applications.

Compared with PT8A3231PEX, PT8A3235WE offers smaller footprint but removes dedicated OFF button support, while PT8A3230PE retains identical mechanical and electrical interface but lacks constant LED mode-both require layout or firmware adaptation for LED behavior alignment.

Availability

PT8A3231PEX is available at Aetrix Electronics and suitable for hair curlers, flat irons, heat guns, and curling wands requiring stable component supply, dual-voltage AC line compatibility, and integrated thermal safety features.

Supply support for PT8A3231PEX 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

Pericom Semiconductor (now part of Diodes Incorporated) specialized in high-performance interface, timing, and power management ICs for consumer and industrial applications before acquisition in 2016.

The PT8A323x series belongs to Pericom's dedicated heating controller product line, designed specifically for cost-sensitive, safety-compliant AC-powered thermal appliances with minimal external components.

FAQ

What is the function of the NTC2 pin on PT8A3231PEX?

NTC2 is a digital output that signals NTC open-circuit condition. When NTC resistance exceeds 20 MΩ, NTC2 is driven low; otherwise it remains in high-impedance state. This enables fail-safe shutdown of the GATE output and initiates LED1 flashing at 1/8 CLK rate, satisfying basic thermal safety requirements without external circuitry.

Can PT8A3231PEX operate from a 3.3 V supply?

No. The absolute minimum VDD is 3.5 V per the Recommended Operating Conditions table. At 3.3 V, internal logic thresholds and ADC reference margins fall outside specification, risking unreliable NTC sampling, incorrect timer counting, and intermittent GATE activation. A 5 V regulated supply is recommended for guaranteed operation across temperature and voltage tolerances.

How does PT8A3231PEX detect 120V vs. 240V line voltage?

It uses CLK input amplitude analysis-not frequency. The internal circuit compares the peak voltage of the CLK signal (derived from AC line via resistive divider) against internal thresholds. Higher amplitude indicates 240 V operation, triggering narrower SCR conduction windows to limit power; lower amplitude selects wider conduction for 120 V, maintaining consistent thermal output across regions.

Is there a recommended bypass capacitor value for VDD?

Yes. A 1.0 µF X5R ceramic capacitor placed within 5 mm of Pin 8 (VDD) and Pin 4 (GND) is specified in application schematics. This stabilizes internal voltage during GATE switching transients and suppresses noise coupling into the sensitive NTC1 analog path, ensuring accurate temperature band detection and reliable timer operation.