Semtech Corporation 1N6157

Overview

1N6157 from Semtech is a transient diverting suppressor (TDS) designed for high-energy EOS protection of 22V-rated I/O or power lines, featuring ±30kV IEC 61000-4-2 ESD immunity, 40A peak pulse current (8/20μs), 27.5–28V clamping voltage at 40A, and 20mΩ dynamic resistance. It protects USB Type-C power delivery buses and industrial load switch inputs.

For engineers reviewing the 1N6157 datasheet, pinout, applications, or equivalent options, key selection criteria include clamping stability across temperature (−40°C to +125°C), low capacitance (175pF @ 22V), DFN 1.6×1.6mm package footprint, and FET-based shunt architecture enabling constant-voltage clamping unlike conventional TVS diodes.

Technical Context

The 1N6157 uses a surge-rated MOSFET as its primary protection element, activated by a precision trigger circuit that senses overvoltage events and drives the FET into low-R_DS(on) conduction. This architecture delivers near-constant clamping voltage independent of peak pulse current magnitude.

Unlike standard TVS diodes whose clamping voltage rises linearly with I_PP (V_C = V_BR + I_PP × R_DYN), the 1N6157 maintains clamping within 27.5–28V from 24A to 40A and across −40°C to +125°C - confirmed by typical characteristics curves in the datasheet.

Key Specifications

Pinout & Package

Package: DFN 1.6 mm × 1.6 mm × 0.55 mm, 6-lead, RoHS-compliant, UL 94V-0 molding compound, lead-free finish, tape-and-reel packaging (3,000 pcs/reel).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ22A, the 1N6157 delivers 8–10V lower clamping at 40A and stable performance across temperature, enabling safer protection of 24V ICs; compared with TDS2211P, it is an identical device with no electrical or mechanical distinction - differing only in orderable part number and internal inventory tracking.

Availability

1N6157 is available at Aetrix Electronics and suitable for USB Type-C power delivery systems, industrial load switch inputs, and 22V IoT power rail protection requiring stable component supply and long-term lifecycle support.

Supply support for 1N6157 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

Semtech Corporation is a U.S.-based fabless semiconductor company specializing in analog and mixed-signal ICs for precision sensing, protection, and signal integrity.

The 1N6157 belongs to Semtech's Transient Diverting Suppressor (TDS) product line, engineered specifically to replace conventional TVS diodes in high-reliability 20–24V systems where clamping voltage stability across temperature and current is critical.

FAQ

What is the exact function of the 1N6157 in a circuit?

The 1N6157 functions as a transient diverting suppressor that actively shunts high-energy EOS events (ESD, lightning surges, EFT) to ground using an integrated surge-rated FET. Unlike passive TVS diodes, it maintains a near-constant 27.5–28V clamping voltage across its full 40A surge rating and −40°C to +125°C operating range - making the 1N6157 ideal for protecting 22V power rails and USB-C VBUS lines where voltage margin is tight.

Is the 1N6157 pin-compatible with standard TVS diodes like SMAJ22A?

No - the 1N6157 uses a 6-pin DFN package (pins 1–3 = GND, pins 4–6 = IN), whereas SMAJ22A is a 2-pin DO-214AC package. The 1N6157 requires three parallel ground connections and three parallel input connections for full 40A rating, and its PCB layout must follow Semtech's recommended land pattern with multiple vias to ground. Direct substitution is not possible without board redesign.

Does the 1N6157 require external bias or control signals to operate?

No - the 1N6157 is fully autonomous and requires no external power, enable signals, or configuration. Its internal trigger circuit monitors voltage across the protected line and automatically activates the shunt FET when an overvoltage event exceeds the breakdown threshold. This makes the 1N6157 a drop-in replacement for passive TVS devices in terms of system integration, though its 6-pin layout differs physically.

How does the 1N6157 achieve constant clamping voltage across varying surge currents?

The 1N6157 achieves constant clamping by using a precision-triggered MOSFET as the main conduction element. When triggered, the FET enters deep saturation with R_DS(on) < 20mΩ, causing clamping voltage to converge toward the trigger circuit's reference voltage (~27.5V) rather than rising linearly with current as in TVS diodes. This behavior is verified in the datasheet's clamping vs. I_PP and temperature curves - confirming the 1N6157 clamps at 27.5–28V from 1A to 40A and −40°C to +125°C.

Can the 1N6157 be used to protect high-speed data lines such as USB 3.2 or PCIe?

No - the 1N6157 has 175pF junction capacitance at 22V, which is too high for high-speed differential data lanes (e.g., USB 3.2 Gen 2 requires <0.3pF). It is intended exclusively for 22V power or single-ended I/O lines like USB-C VBUS, load switch inputs, or 22V backup supplies. For data line protection, Semtech recommends low-capacitance devices like RClamp3371ZC (<0.25pF) alongside the 1N6157 in complete interface solutions.