onsemi MOC70P3

Overview

MOC70P3 from Fairchild Semiconductor is a phototransistor-based optical interrupter switch with transistor output, 5 mm sensing gap, 0.040" aperture, and PCB mount package. It delivers 0.60 mA minimum on-state collector current at IF = 5 mA/VCE = 10 V, 4.0 mA at IF = 20 mA, and 5.5 mA at IF = 30 mA - used in position detection for industrial encoders and motor commutation feedback loops.

For engineers reviewing the MOC70P3 datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed IC(ON) performance across operating temperature (−55°C to +100°C), low VCE(SAT) ≤ 0.40 V, fast switching (t(ON) = 20 µs, t(OFF) = 80 µs), and compatibility with standard IR LED drive circuits.

Technical Context

The MOC70P3 integrates an infrared LED emitter optically coupled to an NPN silicon phototransistor in a single molded housing. Its wide-gap design enables non-contact object detection without mechanical wear, and its transistor output provides direct interface to TTL/CMOS logic or pull-up resistor networks.

It operates with forward current up to 50 mA on the emitter side and supports collector-emitter voltage up to 30 V, with dark current ICEO ≤ 100 nA at VCE = 10 V. Switching speed is load-dependent, optimized for RL = 2.5 kΩ with VCC = 5 V.

Key Specifications

Pinout & Package

Package: 4-pin DIP-style through-hole plastic housing (MOC70P1/P2/P3 common footprint), 0.380" (9.65 mm) body width, 0.506" (12.85 mm) length, 0.270" (6.86 mm) height, 0.100" (2.54 mm) lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar optical interrupter applications.

Compared with TCST2103 and LTH-1550-01, the MOC70P3 offers the widest operational temperature range and highest guaranteed IC(ON) at 20–30 mA drive, making it preferred for high-reliability industrial motion control where thermal stability and output margin are critical.

Availability

MOC70P3 is available at Aetrix Electronics and suitable for industrial encoder feedback, printer paper path monitoring, automotive throttle position sensing, and conveyor belt object counting requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MOC70P3 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

Fairchild Semiconductor was a U.S.-based analog and power semiconductor manufacturer, acquired by ON Semiconductor in 2016; legacy products like the MOC70P3 remain widely supported and distributed.

The MOC70P3 belongs to Fairchild's photointerrupter product line, designed specifically for robust, maintenance-free position and presence sensing in industrial automation, office equipment, and automotive subsystems.

FAQ

What is the maximum forward current rating for the MOC70P3 emitter LED?

The MOC70P3 emitter has an absolute maximum continuous forward current (IF) of 50 mA at TA = 25°C. Derating is required above 25°C at 1.67 mW/°C per note 1 in the datasheet. For reliable long-term operation, typical design practice limits IF to 30 mA, which yields 5.5 mA collector current and stays well within thermal limits.

Does the MOC70P3 require an external base connection for the phototransistor?

No, the MOC70P3 uses a baseless phototransistor configuration - only collector (PIN 3) and emitter (PIN 4) are brought out. This simplifies circuit design by eliminating base biasing components and improves noise immunity in electrically noisy environments where the MOC70P3 is commonly deployed.

Can the MOC70P3 be used with 3.3 V logic systems?

Yes, the MOC70P3 is fully compatible with 3.3 V logic. Its VCE(SAT) ≤ 0.40 V ensures the output remains solidly below the VIH threshold of 3.3 V CMOS inputs, and its 4.0 mA IC(ON) at IF = 20 mA provides sufficient drive strength to sink standard logic input leakage currents while maintaining noise margin.

What is the significance of the "P3" suffix in MOC70P3?

The "P3" suffix denotes the highest sensitivity variant in the MOC70PX family: MOC70P3 guarantees ≥0.60 mA IC(ON) at IF = 5 mA, ≥4.0 mA at IF = 20 mA, and ≥5.5 mA at IF = 30 mA - double the output of MOC70P2 and triple that of MOC70P1 under identical test conditions.

Is the MOC70P3 RoHS compliant and halogen-free?

Yes, the MOC70P3 is RoHS compliant and halogen-free per Fairchild's DS300009 revision history and ON Semiconductor's legacy product compliance documentation. It meets JEDEC J-STD-609A Class 1 for halogen content and adheres to EU Directive 2011/65/EU without exemptions.