Diodes Incorporated PT8A3285WEX

Overview

PT8A3285WEX from Pericom Semiconductor is a mixed-signal CMOS heating controller IC designed for 120V/240V AC-powered thermal appliances. It implements proportional temperature control using an external NTC sensor, provides NTC open-circuit protection, delivers 5–15mA TRIAC gate trigger pulses (200μs width), and integrates internal 5V Zener regulation. Used in hair straighteners and curling irons requiring auto-voltage adaptation and timed heating cycles.

For engineers reviewing the PT8A3285WEX datasheet, PT8A3285WEX pinout, PT8A3285WEX application, or PT8A3285WEX equivalent, key selection criteria include its dual-voltage operation (50/60Hz CLK sync), 1.2-hour heating timer at 50Hz, GATE output drive capability (5mA sink), LED1/LED2 dual-indicator support, and SOIC-8 lead-free/Green packaging compliance.

Technical Context

The PT8A3285WEX uses a 5-bit ADC to digitize NTC voltage for closed-loop proportional control, synchronized to line-frequency CLK input (50/60Hz). Its internal state machine manages three modes: power-on reset, heating-on (with timer countdown), and heating-off (auto-shutdown after timeout).

NTC open detection is implemented via NTC1/NTC2 pins: NTC1 senses NTC voltage while NTC2 outputs a low signal during open-circuit fault. The GATE pin drives TRIACs with precisely timed 160–240μs pulses, scaled by NTC voltage and CLK amplitude level (120V vs 240V detection).

Key Specifications

Pinout & Package

PT8A3285WEX is housed in an 8-pin SOIC package (JEDEC MS-012E/AA), measuring 4.7–5.1mm × 3.8–4.0mm × 1.35–1.75mm, with lead-free and RoHS-compliant Green finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PT8A3284WEX and PT8A3286WEX, the PT8A3285WEX uniquely combines constant-mode LED1, flash-mode LED2, and enabled auto-heating timeout - making it optimal for safety-certified consumer thermal devices needing both user feedback and fail-safe shutdown.

Availability

PT8A3285WEX is available at Aetrix Electronics and suitable for hair styling tools, electric blankets, and beauty appliance manufacturing requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for PT8A3285WEX 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 its 2016 acquisition.

The PT8A328x series belongs to Pericom's dedicated heating controller product line, engineered specifically for cost-sensitive, AC-mains-powered thermal appliances requiring integrated NTC interface, line-synchronized timing, and TRIAC/SCR drive capability.

FAQ

What is the function of the NTC2 pin on PT8A3285WEX?

The NTC2 pin is a dedicated digital output that goes low when the IC detects an open-circuit condition on the external NTC thermistor connected to NTC1. This fault signal enables immediate system-level safety response-such as disabling the GATE output-and requires no external comparator circuitry.

Can PT8A3285WEX operate with a 12V DC supply instead of AC-derived VDD?

No. PT8A3285WEX requires a 3.5–5.5V DC supply referenced to GND; it does not accept 12V directly. The VDD pin must be fed from a regulated low-voltage rail-typically derived from the AC line via resistive dropper and Zener clamp, as shown in the application circuit. Applying 12V will exceed absolute maximum ratings and cause permanent damage.

How does PT8A3285WEX distinguish between 120V and 240V AC line voltages?

It analyzes the amplitude of the CLK input signal: high-amplitude CLK indicates 240V operation and scales TRIAC conduction accordingly; low-amplitude CLK triggers 120V mode. This dual-voltage detection is performed internally without external components and ensures correct heater power delivery regardless of regional mains voltage.

Is the GATE output compatible with standard TRIACs like the BT136 or TIC226?

Yes. The GATE pin delivers 5mA sink current at 0.5V, sufficient to trigger common sensitive-gate TRIACs including BT136-600D and TIC226M. Pulse width (160–240μs) aligns with standard TRIAC turn-on requirements, and the output is rated for repetitive 50/60Hz switching without derating.