Keysight 34951A – 4 Channel D/A Converter with Waveform Memory for 34980A

The 34951A 4-Ch Isolated D/A module (DAC module) has four independent, isolated DAC channels that output DC voltage up to ±16V or DC current up to ±20 mA (Level Output Mode). Since the DACs are electrically isolated, you can stack or combine multiple DACs to have up to ±64 V on a module. It also features a capability to specify and store waveform points (Waveform Trace Mode).

You can control each channel manually, or use the onboard memory to store multiple sequenced points.

Level output mode

The module can generate voltages between -16 V DC and +16 V DC at 500 µV resolution on any or all four channels. Each channel configured for voltage output has hardware remote-sensing capability to ensure that an accurate voltage is present at the load. With the remote sensing feature, the DAC channel outputs an additional voltage to compensate for the voltage drop in the test leads. Thus, using the sense connections, the load voltage equals the programmed voltage as long as the resistance in each sense lead is less than 2.5 ohms and the maximum voltage drop in the output leads is 0.5 volts.

When using the remote-sensing feature, connect sense wires from the load to the High Sense and Low Sense terminals for the desired channels.

Each channel can also generate current between -20 mA and +20 mA at 630 nA resolution. When outputting current the High Sense and Low Sense terminals are not used and are opened. For protection, each channel incorporates a fuse that will open at greater than 20 mA. If an overload condition exists, the fuse will open, but no error or SRQ will be generated. To reset the fuse, remove the overload and wait a few minutes for the fuse to cool.

Waveform (trace) mode

Using the internal waveform point storage, you can output provided sine, square, or ramp and triangle wave shapes, or define your own wave shape with up to 512,000 points. The module can output points with a settling time of 40 µs and a 200 kHz point-to-point update rate.

The on-board memory provides storage for you to create up to 32 voltage or current waveforms. You can apply a different waveform to each channel to output. Or you can apply the same waveform to more than one channel. For each channel you can designate the gain, frequency, and/or offset for its output.

The waveforms are stored in volatile memory. Therefore, whenever power to the 34980A is cycled, the volatile memory empties of data it has contained.

The waveform feature of the 34951A is not intended as a full-featured substitute for a function generator, but as a means of storing point-to-point updates.

Clock in

You can configure each DAC channel on the module to synchronize off either an internally-generated 20 MHz clock or the positive edge of an external user-supplied clock.

An external clock must be less than 10 MHz or indeterminate behavior will result. Additionally, as the maximum point-to-point update rate of the DACs is 200 kHz, if you configure a DAC to run off an external clock, you will need to ensure that the correct clock divisor is also configured for that DAC. For example, if you supply a 10 MHz external clock, the minimum clock divisor is 50 because the maximum update rate is 200 kHz. If a clock divisor less than the minimum is configured, indeterminate behavior will results. Thresholds for the Clock In are 5 V TTL tolerant.

Clock Out

There is one clock output on the DAC module, which you can configure to output at frequencies up to 10 MHz. Since it uses a 16-bit clock divisor, the available output frequencies range in steps of 20 MHz/2¹⁶ with a minimum output frequency of 305 Hz. The output impedance of the Clock Out is 50 ohms.

Trigger In

You can configure each DAC on the module to trigger off an externally provide Trigger In that has a pulse width greater than 100 ns. The Trigger In line is 5V TTL tolerant.

Trigger Out

The DAC module can source a TTL level Trigger Out. Trigger Out has a pulse width between 5 and 10 µs.

The chart below outlines several main features of system control modules for the Keysight 34980A.