Toshiba Semiconductor and Storage TLP171A(TP,F

Overview

TLP171A(TP,F) from Toshiba Electronic Devices & Storage Corporation is a normally-open photorelay IC comprising an infrared LED optically coupled to a photo-MOSFET output stage. It delivers 400 mA maximum ON-state current, 2 Ω max ON-resistance, and 1500 Vrms isolation voltage in a compact SOP-4 package (2.54 mm pitch, 2.1 mm height), enabling solid-state replacement of mechanical relays in low-power control circuits.

For engineers reviewing the TLP171A(TP,F) datasheet, TLP171A(TP,F) pinout, TLP171A(TP,F) application, or TLP171A(TP,F) equivalent, key selection criteria include trigger LED current (≤0.2 mA for t >1 s), OFF-state voltage rating (60 V min), thermal derating behavior, and UL/cUL safety certification compliance for industrial and appliance designs.

Technical Context

The TLP171A(TP,F) implements galvanic isolation via optical coupling between GaAs-based LED input and dual-drain MOSFET output. Its internal structure treats Pins 1–2 as a single anode–cathode pair and Pins 3–4 as paralleled drain terminals-functioning as a two-terminal switch with no gate access.

It operates under recommended conditions of 0.5–25 mA LED forward current and ≤48 V supply voltage, with switching times (t_ON/t_OFF) ranging 1–10 ms depending on drive current and load. Thermal derating applies above 25°C ambient for both LED current and output current ratings.

Key Specifications

Pinout & Package

Package: SOP-4 (Toshiba designation 11-5H1S), surface-mount, 2.54 mm lead pitch, 2.1 mm profile height, 0.1 g typical weight.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PVG612A and PS8101-AX, the TLP171A(TP,F) offers the lowest LED drive requirement (0.2 mA) and best current-handling balance (400 mA @ 2 Ω) in SOP-4, making it optimal for cost-sensitive, space-constrained 24 V DC control systems requiring minimal MCU resource usage.

Availability

TLP171A(TP,F) is available at Aetrix Electronics and suitable for security systems, home electric appliances, and factory automation equipment requiring stable component supply, long-term lifecycle support, and certified isolation performance.

Supply support for TLP171A(TP,F) 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

Toshiba Electronic Devices & Storage Corporation designs and manufactures discrete semiconductors, power devices, and optoelectronics for industrial, automotive, and consumer applications.

The TLP171A(TP,F) belongs to Toshiba's photorelay product line, engineered specifically to replace electromechanical relays in low-voltage DC control circuits where reliability, silent operation, and long service life are critical.

FAQ

What is the maximum continuous ON-state current rating for the TLP171A(TP,F)?

The TLP171A(TP,F) supports a maximum continuous ON-state current of 400 mA at 25°C ambient temperature. Derating applies linearly at −4.0 mA/°C above 25°C, limiting usable current to approximately 240 mA at 65°C. This rating assumes proper PCB copper area for heat dissipation and accounts for the device's 2 Ω max ON-resistance, which determines power dissipation (I²R) and junction temperature rise. Always verify thermal margin using actual board layout and ambient conditions.

Does the TLP171A(TP,F) require an external current-limiting resistor on the LED side?

Yes, the TLP171A(TP,F) requires an external series resistor to limit LED forward current to ≤25 mA (absolute max) and ideally within 0.5–25 mA per recommended operating conditions. For example, driving from a 3.3 V MCU GPIO with 0.2 mA trigger target yields ~15 kΩ resistor value. The resistor ensures stable optical coupling efficiency and prevents LED degradation under sustained operation, especially given the device's low 0.2 mA turn-on threshold.

How is isolation achieved in the TLP171A(TP,F), and what safety standards does it meet?

Isolation in the TLP171A(TP,F) is achieved through optical coupling between the GaAs infrared LED and silicon photo-MOSFET, with physical separation maintained by internal molding compound. It is UL-recognized under UL 1577 (File E67349) and cUL-recognized per CSA Component Acceptance Service No. 5A (same file number), certifying 1500 Vrms withstand voltage for 60 seconds. These approvals validate its use in basic insulation applications per IEC 60747-5-5, including household appliances and industrial controls where functional isolation suffices.

Can Pins 3 and 4 of the TLP171A(TP,F) be used independently?

No, Pins 3 and 4 of the TLP171A(TP,F) are internally shorted drain terminals of the same photo-MOSFET die and must be used in parallel. The datasheet explicitly states the device functions as a two-terminal switch: Pins 1–2 form the LED port, and Pins 3–4 collectively form the output switch port. Using them separately violates the internal construction, risks uneven current sharing, and voids guaranteed specifications including R_ON, I_ON, and thermal performance.

What is the typical turn-on time for the TLP171A(TP,F) under standard test conditions?

The typical turn-on time (t_ON) for the TLP171A(TP,F) is 3.5 ms when tested with R_L = 200 Ω, V_DD = 20 V, and I_F = 0.5 mA, per Figure 11.1 in the official datasheet. Turn-off time (t_OFF) is typically 1.5 ms under identical conditions. Both parameters increase slightly at lower LED drive currents and higher temperatures; design margins should account for the 10 ms max t_ON and 5 ms max t_OFF across full operating range.