J-Link PLUS
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
Software
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.
Multi-platform
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
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.

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.

Performance analysis with Ozone
Technical specifications
General | |
Supported OS | Microsoft 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 |
Mechanical | |
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 interface | JTAG/SWD 20-pin (adapters available) |
JTAG/SWD interface, electrical | |
Power supply | USB-powered Max. 50mA + Target Supply current. |
Target interface voltage (VIF) | 1.2V … 5V |
Current drawn from target voltage sense pin (VTRef) | < 25µA |
Target supply voltage | 5V (derived from USB voltage) |
Target supply current | Max. 300mA |
Reset type | Open drain. Can be pulled low or tristated |
Reset low level output voltage | VOL <= 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 kOhm | VOL <= 20% of VIF |
HIGH level output voltage (VOH) with a load of 10 kOhm | VOH >= 80% of VIF |
For 3.6 <= VIF <= 5V | |
LOW level output voltage (VOL) with a load of 10 kOhm | VOL <= 20% of VIF |
HIGH level output voltage (VOH) with a load of 10 kOhm | VOH >= 80% of VIF |
JTAG/SWD interface, timing | |
Target interface speed | Max. 50 MHz |
SWO sampling frequency | Max. 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.

Explosion view of the J-Link PLUS Compact

Assembly dimensions of the J-Link PLUS Compact
Package content
J-Link PLUS Classic



J-Link PLUS
USB cable
20-pin, 0.1″ target ribbon cable
J-Link PLUS Compact



J-Link ULTRA+
USB cable
20-pin, 0.1″ target ribbon cable