Diodes Incorporated PT8A2515TAEX

Overview

PT8A2515TAEX from Pericom Semiconductor is a CMOS LSI timer IC with internal oscillator, adjustable 30s–20min timing via external R/C network, reset function on negative pulse at OSC pin, relay output (high-active, 20mA sink), and operation from 3.5V to 5.5V. It serves as a standalone programmable timer controller in appliance power sequencing circuits such as toaster heating cycles.

For engineers reviewing the PT8A2515TAEX datasheet, PT8A2515TAEX pinout, PT8A2515TAEX application, or PT8A2515TAEX equivalent, key selection criteria include its integrated oscillator architecture, NC pin handling in SOT23-5 layout, relay drive capability without external driver transistors, and tolerance to 8.192kHz ±4% external R/C frequency variation.

Technical Context

The PT8A2515 implements a dual-oscillator system: an internal 256kHz RC oscillator monitors external 8.192kHz R/C oscillator stability and validates OSC pin input pulses for reset. Its logic control circuit interprets OSC pin state transitions to initiate, restart, or clear the 245720-cycle timer counter.

Timer output resolution is fixed at 30 seconds when F_OSC = 8.192kHz (R1=47kΩ, C1=332pF), scaling linearly with oscillator frequency down to 180Hz (max 20min) and up to 20kHz (min ~30s). The relay output is actively driven high during timing and pulled low upon timeout.

Key Specifications

Pinout & Package

PT8A2515TAEX is packaged in lead-free, RoHS-compliant SOT23-5 with top-mark "PT8A2515TAE" and date code. Pin 5 is NC (not connected) and must remain unconnected per design.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PT8A2515TAEX, PT8A2516TAEX offers complementary output polarity but identical timing accuracy and reliability, while NE555DR increases design complexity, component count, and calibration sensitivity-making it unsuitable for production-grade appliance timers requiring long-term stability.

Availability

PT8A2515TAEX is available at Aetrix Electronics and suitable for toaster controllers, appliance power sequencers, safety shutdown timers, and consumer device restart logic requiring stable component supply across extended production lifecycles.

Supply support for PT8A2515TAEX 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-reliability interface, timing, and power management ICs for consumer and industrial electronics before acquisition in 2016.

The PT8A2515 belongs to Pericom's Simple Timer LSI product line, engineered specifically for cost-sensitive, low-pin-count appliance control applications where MCU-based timing is over-engineered or unavailable.

FAQ

What is the minimum external resistor value for the OSC pin to achieve 20-minute timing?

The 20-minute maximum timer interval requires oscillator frequency ≥180Hz. With C1 = 332pF fixed, R1 must be ≥1.8MΩ per the RC timing formula f ≈ 1/(2.2 × R × C). Using R1 = 2.2MΩ achieves ~185Hz and confirms 20-minute operation per datasheet Fig 1 test conditions.

Can the NC pin (Pin 5) be grounded or tied to VCC without affecting operation?

No. Pin 5 is internally unconnected and must remain floating. Connecting it to GND or VCC may cause latch-up, increased leakage, or erratic oscillator behavior due to parasitic coupling into the SOT23-5 die substrate. The datasheet explicitly prohibits any connection to this pin.

Does the internal 256kHz oscillator operate continuously, or only during external oscillator validation?

The internal 256kHz oscillator runs continuously to monitor external oscillator health and validate OSC pin input pulses. It powers the reset detection logic and provides clocking for the key scan circuit-even when the main timer is idle-ensuring immediate response to reset commands.

Is the relay output capable of driving a 12V/400mW relay coil directly?

No. The relay output sinks ≤20mA at VOL = 0.5V, limiting compatible coils to ≤25V/500mW maximum (e.g., 5V/100mW). For 12V/400mW coils (requiring ≥33mA), an external NPN transistor (e.g., 2N3904) with base resistor is mandatory per the datasheet's typical application circuit on page 4.