Diodes Incorporated PT8A3246WEX

Overview

PT8A3246WEX from Pericom Semiconductor is a mixed-signal CMOS heating controller IC designed for single-key auto-temperature control in 120V/240V AC appliances using external NTC thermistors. It integrates dual-voltage detection, NTC open-circuit protection, 1-hour auto-shutoff timer (50/60 Hz), direct SCR gate drive, and dual-mode LED indication. Used in hair curlers for safe, voltage-adaptive thermal regulation.

For engineers reviewing the PT8A3246WEX datasheet, PT8A3246WEX pinout, PT8A3246WEX application, or PT8A3246WEX equivalent, key selection considerations include its single-key ON/OFF logic, flash-mode LED indicator (Flash1 at 1/32 CLK), NTC-based temperature threshold mapping (VNTC0–VNTC2), and SOIC-8 lead-free/Green package compatibility with high-reliability consumer thermal systems.

Technical Context

The PT8A3246WEX implements a 2-bit ADC-based NTC interface with three programmable voltage thresholds (VNTC0 = 0.385×VDD, VNTC1 = 0.385×VDD, VNTC2 = 0.40×VDD) to determine SCR firing duty cycle and LED behavior. Its internal timer counts 216,000 clock cycles - yielding ~1.2 hours at 50 Hz and ~1 hour at 60 Hz - before forcing auto-off.

It supports dual-line voltage operation by sensing AC line frequency via CLK input and dynamically adjusting GATE output timing to maintain consistent thermal output across 110V and 220V mains. Pin 5 (ON/OFF) serves as both button input and LED1 driver; Pin 7 (OFF/LED) drives LED2 in inverse phase to LED1.

Key Specifications

Pinout & Package

PT8A3246WEX is housed in an 8-pin SOIC package (JEDEC MS-012E/AA), 4.7–5.1 mm wide, 3.8–4.0 mm body width, 1.27 mm pitch, with 0.4–1.27 mm lead length and 0°–8° coplanarity tolerance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PT8A3244WEX and PT8A3245WEX, PT8A3246WEX uniquely delivers Flash-mode LED indication with no auto-heating restart after timeout - making it optimal for safety-critical, single-use thermal cycles where visual confirmation of inactive state is essential.

Availability

PT8A3246WEX is available at Aetrix Electronics and suitable for hair curlers, flat irons, electric blankets, and beauty appliances requiring stable component supply, RoHS-compliant packaging, and certified thermal safety functionality.

Supply support for PT8A3246WEX 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, computing, and communications markets.

The PT8A32xx series was developed specifically for cost-sensitive, safety-critical AC-powered thermal appliances - integrating analog NTC sensing, digital timing, and SCR drive into a single 8-pin CMOS LSI to replace multi-component discrete controllers.

FAQ

What is the function of Pin 2 (NTC2) on PT8A3246WEX?

Pin 2 is an open-drain output used exclusively for NTC open-circuit detection. When the NTC sensor becomes disconnected, this pin pulls low, disabling the GATE output and triggering Flash2 LED behavior (1/8 CLK). It does not source current and requires an external pull-up resistor to VDD for proper operation.

Does PT8A3246WEX require an external crystal or clock source?

No. PT8A3246WEX derives its timing reference directly from the AC mains via the CLK input (Pin 3), which connects to a rectified zero-crossing signal. This eliminates the need for crystals, oscillators, or RC timing networks - reducing BOM cost and board space while ensuring synchronization with line frequency.

How does PT8A3246WEX handle different AC line voltages (110V vs 220V)?

It automatically detects line voltage class by measuring CLK input frequency: 60 Hz indicates 110–120 VAC; 50 Hz indicates 220–240 VAC. Based on this, it adjusts SCR gate timing to deliver consistent thermal output - preventing underheating at 220V or overheating at 110V without user intervention or hardware configuration.

Can PT8A3246WEX drive a TRIAC directly, or is an SCR required?

PT8A3246WEX is optimized for direct drive of SCRs (not TRIACs) via its GATE output (Pin 6), which provides 2.5 mA sink current. While some low-gate-charge TRIACs may activate, the device's timing architecture and safety logic assume half-wave SCR triggering - using a TRIAC requires external phase-control circuitry and invalidates the built-in thermal safety behavior.