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Home > Products > Sensors, Transducers > Optical Sensors > Phototransistors

Vishay Semiconductor Opto Division VEMT3705-GS18

Name: VEMT3705-GS18
Brand: Vishay Semiconductor Opto Division
SKU: VEMT3705-GS18
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: VEMT3705-GS18

Manufacturer:: Vishay Semiconductor Opto Division

Category:: Phototransistors

Package:: 2-SMD, J-Lead

Datasheet:: VEMT3705-GS18.pdf

Description:: PHOTO TRANS. SMD PLCC2

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Product details

Overview

VEMT3705-GS18 from Vishay Semiconductors is a high-speed silicon NPN epitaxial planar phototransistor in a surface-mount PLCC-2 package, rated for 20 V V_CEO, 0.6 mA typical collector light current (I_ca) at 940 nm, ±60° angle of half sensitivity, and AEC-Q102 qualification-used in optical position sensing and encoder feedback loops.

For engineers reviewing the VEMT3705-GS18 datasheet, VEMT3705-GS18 pinout, VEMT3705-GS18 application, or VEMT3705-GS18 equivalent, this page delivers verified phototransistor parameters including spectral response (480–1050 nm), rise/fall times (14/21 μs), thermal resistance (400 K/W), and MSL 3 handling requirements-critical for automotive-grade optocoupler design and IR detection layout validation.

Technical Context

The VEMT3705-GS18 operates as a single-element NPN phototransistor with no base connection, relying on incident irradiance (E_e = 1 mW/cm² at λ = 940 nm) to generate collector current. Its epitaxial planar structure enables fast switching and stable dark current (<200 nA at V_CE = 20 V).

Designed for ambient operation from −40 °C to +100 °C, it features a 400 K/W junction-to-ambient thermal resistance when soldered on a 4 mm × 4 mm PCB pad, and its PLCC-2 package includes a physical notch to identify the collector terminal-ensuring correct orientation during automated placement.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	20 V - Maximum allowable collector-emitter voltage before breakdown; sets upper limit for biasing in open-collector detection circuits.
I_ca (typ)	0.6 mA at E_e = 1 mW/cm², λ = 940 nm - Defines output signal level under standard IR illumination; determines load resistor sizing for digital logic interfacing.
Rise/Fall time	14 / 21 μs - Enables reliable detection of ≥30 kHz optical pulses; suitable for incremental encoder wheel slots with ≤100 μs timing windows.
λ_0.1 range	480–1050 nm - Covers visible blue through near-IR; allows compatibility with common 850 nm and 940 nm IR emitters without filtering.
Angle of half sensitivity	±60° - Provides wide field-of-view for misalignment-tolerant photo-interrupter designs in mechanical encoders and door sensors.
AEC-Q102 qualified	Qualified for automotive electronics - Confirms reliability under temperature cycling, humidity, and mechanical shock per JESD22 standards.
MSL Level	Level 3 (168 h floor life) - Requires dry-pack storage and bake-out if exposed >168 h at <30 °C / <60 % RH prior to Pb-free reflow.

Pinout & Package

PLCC-2 surface-mount package (3.5 × 2.8 × 1.75 mm); notch on package body identifies collector terminal. No base lead-two-terminal device with emitter and collector only.

Pin/Terminal	Circuit Role	Design Meaning
Collector (notch side)	Output current sink node	Connected to pull-up resistor or MCU input; polarity must match NPN configuration-collector supplies current path to ground via emitter.
Emitter	Reference/return node	Internally tied to substrate ground plane; must be connected directly to system GND or low-impedance return path to minimize noise coupling.

Key Features

Feature	Design Value
Fast response	14 μs rise / 21 μs fall enables real-time edge detection in motor commutation and RPM measurement up to 30 kHz.
Wide spectral bandwidth	480–1050 nm sensitivity supports dual-use with visible LEDs (e.g., status indicators) and IR emitters (e.g., VSML3710) in same system.
AEC-Q102 qualification	Validated for automotive cabin sensors and body control modules requiring extended temperature and lifetime reliability.
PLCC-2 mechanical alignment	Notch-based orientation marking eliminates assembly errors during high-speed pick-and-place; reduces optical axis misregistration in paired emitter-receiver assemblies.
Low dark current	Typical 0.2 nA at 25 °C ensures stable high-impedance output state in absence of light-critical for battery-powered wake-on-light applications.

Applications

Photo Interrupters	Rotary Encoders
Use Scenario: Optical beam break detection across a moving flag or slotted disk in industrial automation. IC Role / Device Role / Timing Role: Phototransistor element in reflective or transmissive interrupter pair; converts light/no-light states into digital collector current pulses. Use Value: ±60° angular tolerance accommodates mechanical stack-up variation; 14/21 μs timing supports 30 kHz pulse trains from 120-line encoder wheels.	Use Scenario: Quadrature signal generation from rotating shaft-mounted code disk with alternating opaque/transparent segments. IC Role / Device Role / Timing Role: Light-sensing element in dual-channel encoder module; outputs synchronized I/Q waveforms for direction and speed decoding. Use Value: Matched spectral response with VSML3710 IR emitter ensures consistent signal amplitude across temperature; AEC-Q102 rating enables use in automotive steering angle sensors.
Position Sensors	Miniature Switches
Use Scenario: Non-contact linear or angular position feedback in HVAC damper actuators and printer paper-path detectors. IC Role / Device Role / Timing Role: Ambient-light-immune proximity detector; activated only by controlled IR source, rejecting ambient visible spectrum interference. Use Value: 480–1050 nm bandwidth rejects fluorescent/LED ambient noise while responding strongly to 940 nm emitter; low 0.2 nA dark current prevents false triggers.	Use Scenario: Space-constrained tactile or motion-triggered switch replacement in consumer electronics and medical handheld devices. IC Role / Device Role / Timing Role: Solid-state replacement for mechanical microswitches; provides bounce-free, wear-free actuation via optical interruption. Use Value: PLCC-2 footprint (3.5 × 2.8 mm) fits sub-10 mm board spaces; MSL 3 compliance supports standard SMT reflow without pre-bake for low-volume prototyping.

Photo Interrupters

Rotary Encoders

Use Scenario: Optical beam break detection across a moving flag or slotted disk in industrial automation.

IC Role / Device Role / Timing Role: Phototransistor element in reflective or transmissive interrupter pair; converts light/no-light states into digital collector current pulses.

Use Value: ±60° angular tolerance accommodates mechanical stack-up variation; 14/21 μs timing supports 30 kHz pulse trains from 120-line encoder wheels.

Use Scenario: Quadrature signal generation from rotating shaft-mounted code disk with alternating opaque/transparent segments.

IC Role / Device Role / Timing Role: Light-sensing element in dual-channel encoder module; outputs synchronized I/Q waveforms for direction and speed decoding.

Use Value: Matched spectral response with VSML3710 IR emitter ensures consistent signal amplitude across temperature; AEC-Q102 rating enables use in automotive steering angle sensors.

Position Sensors

Miniature Switches

Use Scenario: Non-contact linear or angular position feedback in HVAC damper actuators and printer paper-path detectors.

IC Role / Device Role / Timing Role: Ambient-light-immune proximity detector; activated only by controlled IR source, rejecting ambient visible spectrum interference.

Use Value: 480–1050 nm bandwidth rejects fluorescent/LED ambient noise while responding strongly to 940 nm emitter; low 0.2 nA dark current prevents false triggers.

Use Scenario: Space-constrained tactile or motion-triggered switch replacement in consumer electronics and medical handheld devices.

IC Role / Device Role / Timing Role: Solid-state replacement for mechanical microswitches; provides bounce-free, wear-free actuation via optical interruption.

Use Value: PLCC-2 footprint (3.5 × 2.8 mm) fits sub-10 mm board spaces; MSL 3 compliance supports standard SMT reflow without pre-bake for low-volume prototyping.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
VEMT3700-GS18	Lower I_ca (0.35 mA typ), same PLCC-2 package and spectral range	Suitable for lower-irradiance environments or higher-impedance load networks where gain margin is acceptable	Select VEMT3700-GS18 when system irradiance is <0.5 mW/cm² or when lower output current reduces power dissipation in high-density layouts.
TEFT4300	TO-92 through-hole package, slower response (tr/tf ≈ 25/35 μs), no AEC-Q102 qualification	Limited to non-automotive, cost-sensitive consumer applications with manual or low-speed SMT assembly	Choose TEFT4300 only for legacy through-hole designs or prototyping where reflow compatibility and automotive qualification are not required.

Compared with VEMT3705-GS18, VEMT3700-GS18 trades light sensitivity for reduced output drive, while TEFT4300 sacrifices surface-mount compatibility and automotive reliability for lower unit cost-making VEMT3705-GS18 the optimal choice for space-constrained, high-reliability IR detection.

Availability

VEMT3705-GS18 is available at Aetrix Electronics and suitable for photo interrupters, rotary encoders, and position sensors requiring stable component supply, AEC-Q102 compliance, and high-speed optical detection performance.

Supply support for VEMT3705-GS18 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 Intertechnology is a global semiconductor manufacturer specializing in discrete components, sensors, and passive elements with emphasis on reliability, precision, and automotive-grade qualification.

The VEMT3705-GS18 belongs to Vishay's high-speed phototransistor product line, engineered specifically for robust optical sensing in automotive, industrial, and consumer motion-control systems where ambient immunity and thermal stability are critical.

FAQ

What is the maximum collector-emitter voltage rating for the VEMT3705-GS18?

The VEMT3705-GS18 has a maximum collector-emitter voltage (V_CEO) rating of 20 V. This value is specified under test condition IC = 1 mA and defines the absolute upper limit for bias voltage applied across the collector and emitter terminals. Exceeding 20 V risks irreversible breakdown. The VEMT3705-GS18 must be used with appropriate current-limiting resistors and supply regulation to ensure safe operation within this boundary.

Is the VEMT3705-GS18 compatible with Pb-free reflow soldering processes?

Yes, the VEMT3705-GS18 is qualified for lead (Pb)-free reflow soldering per J-STD-020, with peak temperature up to 260 °C for ≤10 s. Its moisture sensitivity level is MSL 3, requiring floor life management: devices must be assembled within 168 hours after opening the moisture barrier bag unless baked. The VEMT3705-GS18's packaging and termination materials are fully compliant with RoHS and JEDEC reflow standards.

Does the VEMT3705-GS18 have a base connection for external bias control?

No, the VEMT3705-GS18 is a two-terminal NPN phototransistor with no base lead. It operates exclusively in photodiode-amplified mode-light-generated base current is internally coupled, and output collector current depends solely on irradiance intensity and spectral content. The VEMT3705-GS18 cannot be externally biased or configured as a conventional transistor; its behavior is defined entirely by optical input and collector-emitter bias conditions.

What is the spectral response range of the VEMT3705-GS18, and how does it affect emitter pairing?

The VEMT3705-GS18 exhibits spectral sensitivity from 480 nm to 1050 nm (λ_0.1), with peak response at 950 nm. This broad range enables reliable operation with both visible (e.g., 630 nm red LEDs) and near-IR emitters (e.g., 850 nm or 940 nm). For optimal signal-to-noise ratio, pairing with Vishay's VSML3710 (940 nm) is recommended-the VEMT3705-GS18's responsivity at 940 nm yields 0.6 mA I_ca, maximizing output while minimizing ambient interference.

How is the collector terminal identified on the VEMT3705-GS18 PLCC-2 package?

The collector terminal of the VEMT3705-GS18 is identified by a physical notch on the package body. When viewing the top of the PLCC-2 device with the notch positioned at the upper-left corner, the left-hand lead is the collector and the right-hand lead is the emitter. This marking is standardized across Vishay's PLCC-2 phototransistor series and ensures correct orientation during automated placement and schematic symbol assignment for the VEMT3705-GS18.

VEMT3705-GS18 Specifications

Product attributes: Attribute value

Manufacturer:: Vishay Semiconductor Opto Division

Series:: -

Package/Case:: 2-SMD, J-Lead

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Collector Emitter Breakdown (Max):: 20 V

Current - Collector (Ic) (Max):: 50 mA

Current - Dark (Id) (Max):: 200 pA

Wavelength:: 950nm

Viewing Angle:: 120°

Power - Max:: 100 mW

Mounting Type:: Surface Mount

Orientation:: Top View

Operating Temperature:: -40°C ~ 100°C

Grade:: -

Qualification:: -

VEMT3705-GS18 FAQ

1.How can I place an order for VEMT3705-GS18 through Aetrix?

Please submit a Request for Quotation (RFQ) for VEMT3705-GS18 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for VEMT3705-GS18 reliable?

The price and inventory of VEMT3705-GS18 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for VEMT3705-GS18 is usually 5 days.

3.What payment methods are accepted for VEMT3705-GS18?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for VEMT3705-GS18 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for VEMT3705-GS18?

VEMT3705-GS18 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your VEMT3705-GS18 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for VEMT3705-GS18?

For technical support, including VEMT3705-GS18 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your VEMT3705-GS18 requirements.

6.How does Aetrix verify that VEMT3705-GS18 is sourced from the original manufacturer or authorized distributors?

All VEMT3705-GS18 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that VEMT3705-GS18 meets industry standards.

7.What is the process for return or replacement of VEMT3705-GS18?

All VEMT3705-GS18 units undergo pre-shipment inspection (PSI). If there is an issue with VEMT3705-GS18, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The VEMT3705-GS18 part is unused and in its original packaging.

Return procedure for VEMT3705-GS18:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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