TLP185 surface-mount optocoupler SOP-4

TLP185 Surface-Mount Optocoupler SOP-4 is a high-performance optoelectronic device designed to provide robust galvanic isolation between low-voltage control circuits and higher-voltage sections of a system. This component integrates an infrared LED on the input side with a high-gain phototransistor on the output side within a small SOP-4 (Small Outline Package) form factor. Consequently, the TLP185 effectively prevents ground loops and electrical noise from transferring between the control and load sides. It offers superior isolation capabilities while maintaining a stable current transfer ratio (CTR). Therefore, engineers widely choose this optocoupler for compact, surface-mount designs where safety, noise immunity, and small footprint are critical requirements.

Key Features:

• High Isolation Voltage: Provides guaranteed minimum isolation voltage (V_ISO) of 3750 V_RMS, ensuring maximum safety between input and output circuits.
• Surface-Mount Package: The SOP-4 small outline package allows for high-density mounting and reflow soldering processes in modern PCB manufacturing.
• High Current Transfer Ratio (CTR): Offers excellent efficiency, typically maintaining a high CTR even at low input currents, minimizing LED drive requirements.
• Low Input Current: The device operates reliably with a low forward current (I_F) from the LED, making it compatible with battery-powered and low-power digital logic circuits.
• Fast Switching Speed: Delivers quick rise and fall times, enabling its use in applications requiring medium-speed signal isolation.

Technical Specifications:

• Isolation Voltage (V_ISO): 3750 V_RMS minimum
• Collector-Emitter Voltage (V_CEO): 80 V maximum
• Forward Current (I_F): 50 mA continuous maximum
• Collector Current (I_C): 50 mA continuous maximum
• Current Transfer Ratio (CTR): Available in multiple bins (e.g., 50% to 600% at I_F = 5 mA)
• Operating Temperature Range: −55°C to +110°C
• Switching Speed (t_r / t_f): Typically 2 μs / 3 μs

Mechanical Specifications:

• Package Type: SOP-4 (Small Outline Package, 4-pin)
• Mounting: Surface-Mount Technology (SMT)
• Creepage Distance: ≥ 5.0 mm
• Soldering Process: Compatible with lead-free reflow soldering profiles.

Dimensions:

• Body Length: ≈ 4.4 mm
• Body Width: ≈ 4.4 mm
• Body Height: ≈ 2.1 mm (Maximum)
• Pin Pitch (Between pins): 1.27 mm (Standard for SOP)
• Lead Material: Tinned Copper

Pinout and Wiring:

• Pin 1 (Anode): Connect to the positive side of the input control signal (via a current-limiting resistor).
• Pin 2 (Cathode): Connect to the ground reference of the input control circuit.
• Pin 3 (Emitter): Connect to the ground reference of the isolated output circuit.
• Pin 4 (Collector): Connect to the positive supply (V_CC) of the isolated output side via a pull-up resistor.
• Furthermore, ensure you use separate power supplies and grounds for the input and output sides to maintain the isolation barrier integrity.

Datasheet Reference:

• Download Toshiba TLP185 Datasheet

Commonly Used in:

• Switched-Mode Power Supplies (SMPS): Providing isolated feedback signals for voltage regulation circuits.
• Digital Interfacing: Creating isolated interfaces between dissimilar voltage systems (e.g., 5V logic and 12V/24V systems).
• Medical Equipment: Essential for safety-critical signal isolation where patient contact is possible.

Applications:

• Microcontroller Isolation: Protecting sensitive microcontrollers from high-voltage spikes or transients present on the load side.
• I/O Interfacing: Isolating digital input/output lines in industrial control and factory automation equipment.
• Communication Gateways: Providing safety barriers in data communication lines where common mode noise is a concern.

Equivalent Models:

• PC817 (Sharp/Different Package): A widely known competitor, however, the PC817 typically comes in a DIP-4 package, not SOP-4.
• EL817S (Everlight): A functionally equivalent surface-mount optocoupler in an SOP-4 package, often used as a direct substitute.
• LTV-817S (Lite-On): Another commonly available SOP-4 equivalent offering similar CTR and isolation specifications.

Package Includes:

• 1 x TLP185 Surface-Mount Optocoupler SOP-4