Vishay Semiconductor Opto Division VEMT4700-GS08

Overview

VEMT4700-GS08 from Vishay Semiconductors is a high-speed silicon NPN epitaxial planar phototransistor in PLCC-3 surface-mount package, rated for 70 V_CEO, 50 mA I_C, and ±60° half-sensitivity angle, optimized for visible-to-near-IR detection in photo interrupters and position sensors.

For engineers reviewing the VEMT4700-GS08 datasheet, VEMT4700-GS08 pinout, VEMT4700-GS08 application, or VEMT4700-GS08 equivalent, this page delivers verified phototransistor parameters including radiant sensitivity (450–1080 nm), 6 μs rise/fall time at 1 kΩ load, 0.5 mA typical collector light current, and MSL 3 moisture sensitivity compliance.

Technical Context

The VEMT4700-GS08 operates as a base-connected NPN phototransistor with emitter-collector junction optimized for optical coupling to IR emitters like VSML3710. Its spectral response peaks at 850 nm and extends from 450 nm to 1080 nm, supporting both visible-light sensing and 850/950 nm infrared detection.

Thermal design is constrained by R_thJA = 400 K/W and T_j ≤ 100 °C, with power dissipation derated linearly above 25 °C ambient. Fast switching (2 μs tr/tf at 100 Ω load) enables encoder and counter applications requiring sub-10 μs timing resolution.

Key Specifications

Pinout & Package

PLCC-3 package (3.5 × 2.8 × 1.75 mm) with notch indicating collector terminal; surface-mount footprint compatible with standard IR emitter pairings. Base terminal is externally accessible for bias control or sensitivity tuning.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TEFT4300 and QSE113, the VEMT4700-GS08 provides superior angular tolerance (±60° vs. ±35°/±50°), faster switching (6 μs vs. 10 μs), and base access for sensitivity tuning-making it optimal for high-reliability SMT encoder and position-sensing designs.

Availability

VEMT4700-GS08 is available at Aetrix Electronics and suitable for photo interrupters, rotary encoders, position sensors, and light barriers requiring stable component supply through its End of Life date in February 2026.

Supply support for VEMT4700-GS08 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

Vishay Semiconductors is a global leader in discrete semiconductors and passive components, specializing in high-reliability optoelectronics, power MOSFETs, and precision resistors.

The VEMT4700-GS08 belongs to Vishay's high-speed phototransistor family engineered for industrial automation, motion control, and compact optical sensing-emphasizing SMT compatibility, wide spectral response, and tight angular consistency.

FAQ

What is the maximum operating temperature for the VEMT4700-GS08?

The VEMT4700-GS08 has an operating temperature range of -40 °C to +100 °C. Its junction temperature must not exceed 100 °C, and thermal design must account for R_thJA = 400 K/W on a 4 mm × 4 mm PCB pad. Derating begins above 25 °C ambient, with power dissipation limited to 100 mW at 25 °C and decreasing linearly to zero at 125 °C ambient per the published curve. This ensures reliability in industrial motor control and factory automation environments where the VEMT4700-GS08 is commonly deployed.

Does the VEMT4700-GS08 have a base connection, and how is it used?

Yes, the VEMT4700-GS08 features an externally accessible base terminal (Pin 3), unlike many phototransistors with internally connected or floating bases. This allows engineers to apply reverse bias to reduce dark current (ICEO), forward bias to increase gain and response speed, or connect to feedback networks for analog light-level regulation. In the VEMT4700-GS08, base access directly supports design flexibility in precision light meters and adaptive threshold detectors where fixed-gain phototransistors fall short.

What is the spectral response range of the VEMT4700-GS08, and why does it matter?

The VEMT4700-GS08 exhibits a spectral bandwidth (λ_0.1) from 450 nm to 1080 nm, with peak sensitivity at 850 nm. This broad range enables operation with red visible LEDs (630–660 nm), standard 850 nm IR emitters, and 940–950 nm sources-supporting both human-visible status indication and covert IR sensing. The wide response avoids costly optical filtering in multi-wavelength systems and ensures consistent performance across emitter aging or wavelength drift, critical in long-lifecycle VEMT4700-GS08 deployments.

Is the VEMT4700-GS08 compatible with Pb-free reflow soldering processes?

Yes, the VEMT4700-GS08 is qualified for lead (Pb)-free reflow soldering per J-STD-020, with a peak temperature of 260 °C for ≤10 seconds. Its moisture sensitivity level is MSL 3, requiring floor life ≤168 hours after bag opening at <30 °C and <60 % RH. If exposed beyond this limit, baking per J-STD-020 is mandatory before reflow. These specifications ensure robust manufacturability in modern SMT lines using the VEMT4700-GS08 for high-volume consumer and industrial products.

How does the ±60° angle of half sensitivity affect mechanical design with the VEMT4700-GS08?

The ±60° angle of half sensitivity (ϕ) defines the optical acceptance cone where responsivity remains ≥50 % of peak. This wide angular tolerance relaxes mechanical alignment requirements in photo-interrupter housings and encoder disks-allowing ±0.5 mm lateral misalignment at 5 mm gap without signal loss. It also enables larger air gaps in light-barrier designs, reducing contamination risk and simplifying field service. For the VEMT4700-GS08, this specification directly lowers assembly cost and improves long-term reliability in vibration-prone industrial settings.