J-Link PLUS is a USB-powered JTAG debug probe supporting a large number of CPU cores. Based on a 32-bit RISC CPU, it can communicate at high speed with the supported target CPUs. J-Link is used around the world in tens of thousands of places for development and production (flash programming) purposes.

The J-Link debug probes are supported by all major IDEs including Eclipse, GDB-based IDEs and SEGGER Embedded Studio. For a complete list, please refer to supported IDEs. Including all models, more than 500,000 J-Links have been shipped so far, making J-Link probably the most popular debug probe for Arm cores and the de-facto standard.

Key features

  • Download speed up to 1 MB/s
  • Unlimited breakpoints in flash memory (Flash Breakpoints)
  • Use with Ozone, RDI / RDDI and J-Flash
  • Built-in VCOM functionality
  • Supports a broad range of microcontrollers
  • Supports direct download into RAM and flash memory
  • Free software updates


All software is included free of charge. It comes with licenses for all J-Link related SEGGER software products, such as J-Link Unlimited Flash Breakpoints, Ozone, RDI/RDDI, J-Flash, J-Link GDB Server, providing the optimum debugging solution for professional developers.

J-Link PLUS can be used with almost all Arm debuggers, enabling download to flash memory with an unlimited number of breakpoints when debugging programs located in flash memory of most popular Arm microcontrollers. It also comes with the license to use J-Flash, SEGGER’s popular flash programming software.


As a multi-platform solution, J-Link PLUS comes with the setup and control software for Linux, macOS and Windows. Software and firmware updates are included. Similarly, use on all currently supported target devices, and any that will be added, is also included.


J-Flash is part of the J-Link Software and Documentation Package and allows the programming of the internal and external flash memory of a microcontroller-based embedded system via J-Link.

Flash Breakpoints

The J-Link PLUS comes with an additional feature, called Unlimited Flash Breakpoints. Unlimited Flash Breakpoints allow the user to set an unlimited number of breakpoints when debugging in flash memory.

Ozone — The J-Link debugger

Ozone is the debugger for J-Link and J-Trace. It includes all well-known debug controls and information windows and makes use of the best performance of J-Link and J-Trace debug probes.

Standalone debugger

Ozone focuses on debugging. There are no compiler or project window distractions. All debug windows can be moved, resized and docked, to provide you with the workspace you need.

Ozone offers all well-known debug controls and information windows, and more. Instruction trace, power graph, live watches, and real-time terminal I/O further extend these capabilities.

J Link Pro Standalone Debugger

Debugging with Ozone

Performance analyzer

With J-Link’s High-Speed Sampling technology, Ozone can sample and visualize an embedded system’s variables over time. Checking values and flags in the debugger, while the target keeps running, is easy.

J-Link’s power measurement features enable you to record the power consumption of your target device in a debug session. This is especially helpful when you are developing a low-power device and need to know how power consumption changes when you enable or disable certain components.

J Link Pro Performance Analyzer

Performance analysis with Ozone

Technical specifications

Supported OSMicrosoft Windows (x86/x64), Linux (x86/x64/Arm), macOS (x86/Apple Silicon)
Electromagnetic compatibility (EMC)EN 55022, EN 55024
Operating temperature+5°C … +60°C
Storage temperature-20°C … +65 °C
Relative humidity (non-condensing)Max. 90% rH
Size of J-Link PLUS Classic (without cables)100mm x 53mm x 27mm
Weight of J-Link PLUS Classic (without cables)70g
Size of J-Link PLUS Compact (without cables)46mm x 46mm x 17mm
Weight of J-Link PLUS Compact (without cables)20g
Available interfaces
USB interface (J-Link PLUS)USB 2.0 (Hi-Speed); USB Type B
USB interface (J-Link PLUS Compact)USB 2.0 (Hi-Speed); Micro USB
Target interfaceJTAG/SWD 20-pin (adapters available)
JTAG/SWD interface, electrical
Power supplyUSB-powered Max. 50mA + Target Supply current.
Target interface voltage (VIF)1.2V … 5V
Current drawn from target voltage sense pin (VTRef)< 25µA
Target supply voltage5V (derived from USB voltage)
Target supply currentMax. 300mA
Reset typeOpen drain. Can be pulled low or tristated
Reset low level output voltageVOL <= 10% of VIF
For the whole target voltage range (1.2V <= VIF <= 5V)
LOW level input voltage (VIL)VIL <= 40% of VIF
HIGH level input voltage (VIH)VIH >= 60% of VIF
For 1.2V >= VIF <= 3.6V
LOW level output voltage (VOL) with a load of 10 kOhmVOL <= 20% of VIF
HIGH level output voltage (VOH) with a load of 10 kOhmVOH >= 80% of VIF
For 3.6 <= VIF <= 5V
LOW level output voltage (VOL) with a load of 10 kOhmVOL <= 20% of VIF
HIGH level output voltage (VOH) with a load of 10 kOhmVOH >= 80% of VIF
JTAG/SWD interface, timing
Target interface speedMax. 50 MHz
SWO sampling frequencyMax. 30 MHz
Data input rise time (Trdi)Trdi <= 20ns
Data input fall time (Tfdi)Tfdi <= 20ns
Data output rise time (Trdo)Trdo <= 10ns
Data output fall time (Tfdo)Tfdo <= 10ns
Clock rise time (Trc)Trc <= 3ns
Clock fall time (Tfc)Trc <= 3ns

Assembly dimensions

The compact variant of the J-Link PLUS is designed to mount securely and unobtrusively into development or end user equipment. The small size and two mounting holes enable placing the J-Link PLUS Compact into existing equipment housings or to reserve space for direct-to-PCB mounting.

Typical applications are test fixtures that are used to automate firmware verification during development, or long-term test setups. It also can be used for integrated firmware reflash or service purposes inside end equipment, minimizing the number of tools that service technicians must carry around.

J-Link Plus Compact

Explosion view of the J-Link PLUS Compact

J-Link Plus Compact Dimensions

Assembly dimensions of the J-Link PLUS Compact

Package content

J-Link PLUS Classic

J-Link Plus
USB Cable
20Pin Target Ribbon


USB cable

20-pin, 0.1″ target ribbon cable

J-Link PLUS Compact

J-Link Plus Compact
micro USB Cable
20Pin Target Ribbon


USB cable

20-pin, 0.1″ target ribbon cable