Specifications

2-11

Programming the HP 71612 Series

Handling Coupled Parameters

The groups of commands used to configure the electrical levels at the pattern generator's

DATA OUT, DATA OUT, CLOCK OUT, CLOCK OUT, PARALLEL DATA OUTPUTS

and SUBRATE CLOCK OUTPUT have a coupling which makes their use order sensitive.

The restrictions on the parameter values that these commands can take and the order in

which the commands need to be issued are as follows:

1. Whenever either the external attenuation or termination voltage is configured the out-

put amplitude for that port is set to its minimum value and the high-level is set to Vt/2.

It is therefore almost always a requirement to configure the amplitude and high-level

after changing either the attenuation or termination.

2. For DATA OUT, DATA OUT, CLOCK OUT and CLOCK OUT whilst the attenuation

is set to 0 dB, if the termination voltage is set to 0 Volts, then the maximum value of

high-level is ±1.5 Volt. If the termination voltage is set to −2 Volts, then the maximum

value of the high-level is +0.0 Volts. (For the PARALLEL DATA OUTPUTS and SUB-

RATE CLOCK OUTPUT the maximum high-level is +0.0 Volts for either termination.)

3. Values of high-level below −2 Volts are restricted according to the value of amplitude.

This is shown in the accompanying Figure.

4. If new values of amplitude and high-level are issued, then care needs to be exercised as

described below. These are best described with the aid of a diagram.

Figure 2-1 Clock/Data Amplitude and High-Level Relationship with 0V

Termination