Diodes Incorporated PT8A3284PEX

Overview

PT8A3284PEX from Pericom Semiconductor is a mixed-signal CMOS heating controller IC designed for dual-voltage (120V/240V) AC-powered thermal appliances. It implements NTC-based proportional temperature control, auto-off timing (1.15–1.25 hr), and TRIAC gate triggering up to 15 mA. Used in hair straighteners and curling irons, it integrates internal Zener regulation (4.5–5.5 V), NTC open detection, and dual LED drive outputs.

For engineers reviewing the PT8A3284PEX datasheet, PT8A3284PEX pinout, PT8A3284PEX application, or PT8A3284PEX equivalent, key selection criteria include its 50/60 Hz clock-synchronized heating timer, GATE output pulse width (160–240 µs), NTC1/NTC2 differential sensing interface, and SOIC-8 lead-free packaging compatible with reflow assembly.

Technical Context

The PT8A3284PEX operates as a closed-loop thermal controller using an integrated 5-bit ADC to sample NTC voltage at NTC1 while monitoring NTC continuity via NTC2 output. Its internal state machine transitions between Reset, Heating-On, and Heating-Off modes based on CLK frequency (50/60 Hz) and timer expiration (216,000 clock cycles).

It delivers proportional TRIAC trigger pulses synchronized to the AC zero-crossing via CLK input, with GATE output amplitude and duty modulated by NTC voltage level and detected line voltage (120V vs. 240V). LED1/LED2 outputs support flash or constant indication per mode configuration.

Key Specifications

Pinout & Package

PT8A3284PEX is available in lead-free SOIC-8 (JEDEC MS-012E/AA) package, 4.7–5.1 mm wide, 3.8–4.0 mm body width, 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PT8A3284PEX, PT8A3285WE offers identical thermal control but fixed LED behavior, while PT8A3286WE removes the safety timer-making PT8A3284PEX optimal for certified consumer appliances requiring both flash indication and guaranteed auto-shutoff.

Availability

PT8A3284PEX is available at Aetrix Electronics and suitable for hair styling tools, electric blankets, beauty steamers, and portable thermal appliances requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for PT8A3284PEX 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 semiconductor company specializing in high-performance interface, timing, and power management solutions for consumer, computing, and communications markets.

The PT8A328x series belongs to Pericom's dedicated thermal control product line, engineered specifically for cost-sensitive, safety-critical AC-heated consumer appliances with minimal external component count.

FAQ

What is the function of the NTC2 pin on PT8A3284PEX?

NTC2 is an open-drain digital output that pulls low when the NTC sensor connected to NTC1 is detected as open-circuited. This signal can be monitored externally to force system-level shutdown or alert users. It is not an input-it is actively driven low during fault conditions and remains high-impedance otherwise, per datasheet Pin Description Table.

Can PT8A3284PEX directly drive a 400V TRIAC like the BT139-600?

Yes-PT8A3284PEX delivers 5 mA sink current at 0.5 V on the GATE pin, sufficient to trigger standard sensitive-gate TRIACs such as the BT139-600. No external buffer is required if the TRIAC's gate trigger current (IGT) is ≤5 mA and gate threshold voltage (VGT) is ≤1.5 V, as confirmed in the DC Electrical Characteristics table.

How does PT8A3284PEX distinguish between 120V and 240V line voltages?

It analyzes the amplitude of the CLK input signal derived from the AC line. Higher CLK voltage indicates 240V operation, causing the internal control logic to reduce proportional output duty to prevent overheating; lower CLK voltage triggers higher duty for 120V lines. This is implemented in hardware without firmware or configuration pins.

Is the internal Zener diode on VDD intended for primary power regulation?

No-the internal Zener (4.5–5.5 V) serves as a voltage clamp and reference for internal analog blocks, not as a primary regulator. The device requires an external 3.5–5.5 V supply; the Zener protects against transient overvoltage on VDD and stabilizes bias points, as specified under Maximum Ratings and DC Electrical Characteristics.