STMicroelectronics PKC-136

Overview

PKC-136 from STMicroelectronics is a monolithic integrated transient voltage suppressor combining a 700 V repetitive peak reverse voltage (V_RRM) bidirectional Transil™ clamping diode and a series blocking diode in a single DO-15 package, delivering 219 V surge clamping voltage at 2.7 A (10/1000 µs), 4 Ω dynamic resistance, and 35 pF junction capacitance - used for MOSFET protection in flyback power supplies.

For engineers reviewing the PKC-136 datasheet, PKC-136 pinout, PKC-136 application, or PKC-136 equivalent, this device supports high-integration EMI reduction in offline AC-DC converters, offers fast assembly via axial leaded DO-15 mounting, and enables reduced standby losses through low leakage (1 µA @ 136 V, T_j = 25°C).

Technical Context

The PKC-136 integrates a bidirectional Transil™ (V_BR = 160 V, ±10 V tolerance) with a series-connected blocking diode to prevent reverse conduction during clamping, enabling unidirectional surge suppression in flyback snubber circuits. Its 45 ns reverse recovery time (I_F = 1 A, dI_F/dt = −50 A/µs) and 12–18 V peak forward voltage (I_F = 3 A, T_j = 25–125°C) support fast transient response without parasitic turn-on.

Thermal design is enabled by R_th(j-l) = 40 °C/W (lead length = 10 mm) and R_th(j-a) = 105 °C/W on FR4; copper area under leads directly reduces thermal resistance - e.g., 3.5 cm²/lead lowers R_th(j-a) to 60 °C/W - supporting stable operation up to T_j = 150°C and T_stg = −40 to +150°C.

Key Specifications

Pinout & Package

PKC-136 uses a DO-15 axial-leaded package (6.05–6.75 mm body length, 2.95–3.53 mm diameter, 26–31 mm lead length), with cathode identified by a ring marking on the diode end. The device has two terminals: anode and cathode - no internal pin numbering, as it is a two-terminal discrete device.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMCJ70CA and P6KE70A, PKC-136 uniquely integrates clamping and blocking functions in one DO-15 device, eliminating layout error risk, reducing parasitic inductance, and enabling tighter clamping control in flyback snubbers - critical where MOSFET V_DSS margin is constrained.

Availability

PKC-136 is available at Aetrix Electronics and suitable for AC-DC flyback converters, industrial SMPS primary-side protection, and LED driver flyback circuits requiring stable component supply, long-term lifecycle continuity, and traceable sourcing.

Supply support for PKC-136 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, power, MCU, and sensor solutions for automotive, industrial, and consumer markets.

PKC-136 belongs to ST's ASD™ (Application Specific Discretes) product line, engineered specifically for high-reliability transient suppression in power conversion topologies - emphasizing integration, thermal robustness, and precise clamping behavior.

FAQ

What is the maximum peak pulse current PKC-136 can handle?

PKC-136 is rated for 2.7 A peak pulse current under 10/1000 µs waveform per Figure 8 of its datasheet. At this current, clamping voltage reaches 219 V. Pulse power capability depends on duration: e.g., 1 kW for 100 µs (Fig. 1), de-rating linearly with increasing pulse width or junction temperature.

Can PKC-136 be used in bidirectional clamping applications?

No - PKC-136 is inherently unidirectional due to its internal series blocking diode. It clamps only positive transients applied to the anode relative to cathode. For bidirectional protection, a discrete Transil™ like SMBJ70CA must be used instead.

How does PKC-136 reduce EMI emissions compared to RC snubbers?

By replacing lossy RC snubbers, PKC-136 eliminates resistive dissipation and associated broadband noise. Its fast 45 ns recovery and low 35 pF capacitance avoid resonant ringing, while precise 160 V breakdown ensures clamping occurs only during true overvoltage events - reducing conducted and radiated EMI by 6–8 dB in typical 65–130 kHz flyback designs.

What is the recommended PCB layout for optimal thermal performance?

Mount PKC-136 on FR4 with 3.5 cm² copper area per lead to achieve R_th(j-a) = 60 °C/W (vs. 105 °C/W on minimal pads). Use 1 mm track width, 25 mm length, and 4 mm pad diameter per lead. Avoid thermal isolation - maximize copper pour connectivity to ambient to sustain 1.5 W continuous dissipation at T_amb ≤ 70°C (Fig. 3).