J-Link ULTRA+ is a JTAG/SWD debug probe designed for Arm/Cortex. It is fully compatible to the standard J-Link and works with the same PC software.

Based on the highly optimized and proven J-Link, it offers even higher speed as well as target power measurement capabilities due to the faster CPU, built-in FPGA and high-speed USB interface.

Key features

  • Download speed up to 4 MB/s
  • Unlimited breakpoints in flash memory (Flash Breakpoints)
  • Use with Ozone, RDI/RDDI and J-Flash
  • Additional LEDs for power and RESET indication
  • 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.


As a multi-platform solution, J-Link ULTRA+ 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.


Up to 4 MB/s download speed make J-Link ULTRA+ the fastest debug probe on the market.

Flash Breakpoints

The J-Link ULTRA+ 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 (without cables)100mm x 53mm x 27mm
Weight (without cables)73g
Available interfaces
Ethernet interface100 Mbit/s
USB interfaceUSB 2.0 (Hi-Speed)
Target interfaceJTAG/SWD 20-pin
JTAG/SWD interface, electrical
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. 100 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
Analog power measurement interface
Sampling frequency200 kHz
Resolution50 uA

Package content

J-Link Ultra Plus
USB Cable
20Pin Target Ribbon


USB cable

20-pin, 0.1″ target ribbon cable