Agilent Technologies L4400 manual Signal. However, both a user-supplied external clock

L4451A 4-Channel Isolated D/A Converter with Waveform Memory 9

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 instrument memory. Therefore, whenever power is cycled, the volatile memory empties of data it has contained.

The waveform feature of the L4451A 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 instrument 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, 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 external clock input 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 Ω.

N O TE	The line between external Clock Out and external Clock In is shared.
	You can use the external Clock Out to provide the external Clock In
	signal. However, both a user-supplied external clock and the
	module’s Clock Out cannot drive the line at the same time.

Trigger In

You can configure each DAC on the module to trigger off an externally provided ‘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 ∝s.

L4400 User’s Guide 225