Diodes Incorporated PT8A3242WEX

Overview

PT8A3242WEX from Pericom Semiconductor is a mixed-signal CMOS heating controller IC designed for automatic temperature regulation in dual-voltage (120V/240V) appliances using external NTC sensors. It features NTC open-circuit protection, direct SCR gate drive, auto power-off timer (~1 h @ 60 Hz), and dual-mode LED indication. It operates across –20°C to +85°C ambient with 3.5–5.5 V supply and is used in hair curlers.

For engineers reviewing the PT8A3242WEX datasheet, PT8A3242WEX pinout, PT8A3242WEX application, or PT8A3242WEX equivalent, key selection considerations include NTC-based thermal feedback integration, 8-pin SOIC-8 package compatibility, SCR-trigger timing behavior at 50/60 Hz line frequency, and single-key control mode with flash-type LED indication.

Technical Context

The PT8A3242WEX implements a 2-bit ADC for NTC voltage sampling (VNTC0 = 0.385×VCC, VNTC1 = 0.385×VCC, VNTC2 = 0.40×VCC) and uses line-frequency CLK input (50/60 Hz) as both timing reference and zero-crossing sync for phase-controlled SCR triggering. Internal logic maps NTC voltage ranges to GATE duty cycle (0%, 12.5%, 25%, or 100%) and LED flash patterns.

It supports two-button (ON/OFF) or single-button (ON/OFF toggle) operation depending on variant; PT8A3242WEX uses two keys and flash-mode LED indication with no auto-heating-off timer enabled - distinguishing it from PT8A3240/4/6. NTC2 pin provides open-detection output, while GATE delivers active-high SCR trigger pulses up to 2.5 mA sink current.

Key Specifications

Pinout & Package

PT8A3242WEX is packaged in lead-free, RoHS-compliant SOIC-8 (JEDEC MS-012E/AA), with 1.27 mm pitch, body width 3.8–4.0 mm, and height 1.35–1.75 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PT8A3240WEX (timer-enabled) and PT8A3246WEX (single-key), PT8A3242WEX provides deterministic two-key control without timeout - ideal for applications requiring sustained heating under user supervision and simplified firmware-free operation.

Availability

PT8A3242WEX is available at Aetrix Electronics and suitable for hair curlers, flat irons, curling wands, and travel hair dryers requiring stable component supply, dual-voltage compatibility, and integrated NTC-based thermal management.

Supply support for PT8A3242WEX 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) is a fabless provider of high-performance interface, timing, and power management ICs for consumer, computing, and industrial applications.

The PT8A32xx series was developed specifically for cost-sensitive, microcontroller-free thermal control in small-appliance heating elements - emphasizing integration of NTC interface, line-synchronized timing, and SCR drive in minimal footprint.

FAQ

What is the function of the NTC2 pin on PT8A3242WEX?

NTC2 is an open-circuit detection output that goes low when the NTC sensor resistance exceeds 20 MΩ. This condition disables the GATE output and causes LED2 to flash at 1/8 the CLK frequency, providing fail-safe thermal shutdown without external circuitry.

Does PT8A3242WEX support both 50 Hz and 60 Hz AC line frequencies?

Yes - the device uses the CLK input directly from the AC line and scales its internal 216,000-cycle timer accordingly: ~1.2 hours at 50 Hz and ~1 hour at 60 Hz. However, PT8A3242WEX has the auto power-off timer disabled, so this timing applies only to variants like PT8A3240WEX.

Can PT8A3242WEX drive a 4 A TRIAC directly?

Yes - the GATE pin provides 2.5 mA sink current at 4.5 V output, sufficient to trigger common 4 A TRIACs (e.g., MAC4DC, BT136) without external amplification, provided gate threshold voltage is ≤1.5 V and gate charge requirement is ≤100 nC.

How does PT8A3242WEX distinguish between 120 V and 240 V line voltages?

It does not measure RMS voltage directly. Instead, it infers line voltage from CLK amplitude and internal calibration: higher CLK swing (≥3.5 Vpp) indicates 240 V operation, triggering reduced SCR conduction duty to prevent overheating; lower swing (<3.5 Vpp) enables full-range phase control for 120 V.