Diodes Incorporated PT8A3305HWEX

Overview

PT8A3305HWEX from Pericom Semiconductor is a ceramic heating controller IC designed for direct SCR-triggered temperature regulation in alumina heater systems. It integrates PTC-based temperature sensing, 50/60 Hz AC line synchronization via CLK input, internal 5 V zener regulation, and auto power-off timing (1.2 hr @ 50 Hz). It supports one-key ON/OFF toggle operation and constant LED indication, targeting compact, self-contained heating modules operating at 120/240 VAC.

For engineers reviewing the PT8A3305HWEX datasheet, PT8A3305HWEX pinout, PT8A3305HWEX application, or PT8A3305HWEX equivalent, key selection considerations include its dual-voltage AC compatibility, integrated SCR gate drive (200 µs pulse, >15 mA peak), on-chip voltage reference (REF), thermal insensitivity (–20°C to +85°C operation), and DIP-8/SOIC-8 package options with lead-free/Green compliance.

Technical Context

The PT8A3305HWEX implements a dedicated analog control loop for ceramic heaters: it samples heater resistance via the PTC pin using an internal comparator referenced to REF, synchronizes switching to AC zero-crossing via CLK, and delivers high-current gate pulses (Tal_GATE = 120–300 µs) directly to SCR anodes. Its internal POR circuit ensures reliable startup, and the built-in timer counts AC line cycles (216,000 cycles) to enforce automatic shutdown.

Unlike general-purpose microcontrollers, this device eliminates external temperature sensors and discrete timing components by embedding a calibrated voltage reference (REF), VB bias generation, and LED driver output (LED pin) with constant-on behavior. Its dual-voltage support (120/240 VAC) is achieved through AC-synchronized clocking and robust input threshold design (VKON = 0.8–1.1 V), not digital configuration.

Key Specifications

Pinout & Package

PT8A3305HWEX is available in lead-free, RoHS-compliant SOIC-8 (JEDEC MS-012E/AA) package, measuring 4.7–5.1 mm × 3.8–4.0 mm × 1.35–1.75 mm (A dimension), with 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PT8A3305HPE and PT8A3301LWE, the PT8A3305HWEX uniquely combines SOIC-8 surface-mount compatibility, one-key toggle operation, and constant LED indication-making it optimal for space-constrained, cost-sensitive consumer heating appliances with minimal user interface.

Availability

PT8A3305HWEX is available at Aetrix Electronics and suitable for electric kettles, ceramic cooktops, space heaters, and industrial dryers requiring stable component supply, lead-free compliance, and long-lifecycle availability.

Supply support for PT8A3305HWEX 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 industrial markets before its 2016 acquisition.

The PT8A330x series was developed specifically for ceramic heating system integration-replacing discrete analog controllers with a single-chip solution supporting PTC sensing, SCR drive, AC synchronization, and safety timers.

FAQ

What is the function of the VB pin on PT8A3305HWEX?

The VB pin provides a low-impedance bias voltage (≤15 Ω RON) to the PTC thermistor network. It establishes the current path for temperature-dependent resistance measurement and enables fast thermal response by minimizing RC time constants. VB is not a power supply but a controlled current source node referenced internally to VDD and GND.

Can PT8A3305HWEX drive a 40 A SCR directly?

No. The GATE output delivers >15 mA peak current with 200 µs pulse width-sufficient for triggering 20 A SCRs per datasheet validation. Driving a 40 A SCR would require external amplification (e.g., Darlington pair or MOSFET buffer), as gate charge requirements scale with SCR rating and may exceed the IC's safe operating area.

How does the auto power-off timer behave if the heater is cycled ON/OFF manually?

The timer resets on every OFF command (VDD pulled low or PTC threshold crossed for OFF state). It only runs continuously during uninterrupted heating-starting at first ON and stopping upon OFF or power loss. Manual cycling does not accumulate time; each ON event initiates a fresh 1.2-hour countdown at 50 Hz.

Is the REF pin intended for external connection or internal use only?

The REF pin outputs a stable 0.7 V reference used internally by the comparator for PTC voltage comparison. It must be connected to the PTC network (via resistor divider) and cannot be left floating or loaded beyond 100 µA sink/source. External filtering (e.g., 10 nF capacitor to GND) is recommended to suppress noise coupling into the precision reference path.