Introduced in 1989; see HP Journal of April 1989.

“An 8 1/2-Digit Digital Multimeter Capable of 100,000 Readings per Second and Two-Source Calibration. A highly linear and extremely flexible analog-to-digital converter and a state-of-the-art design give this DMM new performance and measurement capabilities for automated test, calibration laboratory, or R&D applications.”

The 3458A multimeter is HP-IB (IEEE 488) programmable and an enhanced implementation of a multislope ADC achieving a range of speeds and resolutions from 16-bit resolution at 100,000 readings per second to 28-bit resolution at six readings per second. The ADC linearity has deviations that are less than 0.1 ppm of input.

The 3458A was released under the Hewlett Packard brand, but also had Agilent branding and is currently selling under the Keysight brand. Agilent is a spinoff of the Test & Measurement division (including optics, instrumentation, chemical analysis, and medical equipment product lines) of HP, while Keysight is a further spinoff of the test and measurement product lines from Agilent.

• Ranges : 100mV to 1000V
• Sensitivity: 10nV
• Accuracy 1yr(of reading+range): 9+3ppm@100mV, 8+0.3@1V, 8+0.05ppm@10V, 10+0.3ppm@100V, 10+0.1@1000V
• Accuracy 24h(of reading+range): 2.5+3ppm@100mV, 1.5+0.3@1V, 0.5+0.05ppm@10V, 2.5+0.3ppm@100V, 2.5+0.1@1000V
• Input resistance : 10GΩ on ranges up to 10V; 10MΩ +- 1% on 100V and 1000V ranges

• >2MHz true RMS
• Ranges: 10mV to 1000V
• Resolution: 10nV to 1mV (6.5digit)
• Best Accuracy (%reading+%range): 0.02+0.01@100mV-10V (100Hz-20KHz)
• Input impedance: 1MΩ with < 140pF

• Ranges: 10Ω to 1GΩ
• Sensitivity: 10 μΩ to 100Ω
• Open Circuit voltage: 12V (10-10MΩ), 5V (100MΩ & 1GΩ)

• Ranges: 100nA, 1μA, 10μA, 100μA, 1mA, 10mA, 100mA, 1A
• Burden voltage : 0.05V, 0.045V. 0.05V, 0.075V, 0.1V, 0.1V, 0.25V, <1.5V

• Ranges: 100μA, 1mA, 10mA, 100mA, 1A
• Burden voltage : 0.1V, 0.1V,0.1V, 0.25V, <1.5V

Agilent 3458A Datasheet

The 3458A contains one main CPU (Motorola 68HC000P8), one microcontroller in the analog domain (Intel 80C51BH) and one on the outguard power supply (Intel 80C51BH). The latest outguard power supply has changed.

• XDEVS 3458A Genaral information page Includes a table with firmware links towards bottom of page, includes CALROM tool to read calibration data.

• Documentation, repair and Images Xdevs 3458A repair page with pictures

• WinGPIB by Ian Johnston Windows GPIB functionality to many brands and types of test instruments, includes CAL memory copy
• XDEVS remote control guide for 3458A, includes RaspberryPi+ Python GPIB guide