LeCroy 4516 16-Channel, 3-Fold Programmable Logic Unit

OVERVIEW

The LeCroy Model 4516 is a high-speed, multichannel 3-fold coincidence unit designed to provide the flexibility of full CAMAC system control and general-purpose logic functions to meet a wide range of coincidence requirements in modern particle physics experiments. Oriented toward large trigger logic use, the 4516 offers low cost and high density, exceptionally high speed with low complexity, and local or remote programmability of logic functions. It is designed to be directly compatible with its companion module, the LeCroy Model 4416 16-channel discriminator.

Low-Cost/High Density

The 4516 offers significant savings over conventional NIM logic units. Packaged 16 channels to a single-width CAMAC module, it not only costs less per channel, but also occupies substantially less rack space and decreases the cost of associated cabling and power supply hardware.

The high density of the 4516 is made possible by the extensive use of ECL, by the use of cable headers designed to mate with 16-channel twisted pair flat cable, and by the implementation of the CAMAC standard. Lemo connectors for the common Veto and the OR outputs are located on the rear panel to conserve front panel space. Use of the CAMAC standard permits high density by providing increased power with adequate cooling to maintain reliable operation.

High Speed/Low Complexity

With a minimum coincidence width of only 3.5 nsec, the Model 4516 is perfectly compatible with the Model 4416 discriminator. This permits high trigger efficiency through low system deadtime. Use of ECL logic elements permits coincidence decisions in excess of 150 MHz.

The complementary ECL outputs of each 4516 channel are designed for use with inexpensive, flat twisted-pair cables, allowing fast and accurate system interconnection. The low parts count resulting from the elimination of the usual ECL-to-NIM conversion stage yields low cost and high reliability. Output durations are equal to the coincidence overlap. Convenience of use is also made possible by ECL-level inputs, which can either receive and terminate incoming signals in 100 Ohm, or receive and pass on incoming signals off a high impedance for further logic or scaler use.

Local Or Remote Programmability of Logic Functions

Two rear-panel switches determine whether the 4516 is in Local or Remote Mode. In the Local Mode, manual and/or selection of logic gates 0 and 1 is made via these 2 rear-panel switches. In the Remote Mode, this selection is made via CAMAC command if the rear panel control switches are in center position (AND/ REMOTE/OR). Front-panel LED's indicate the logical AND status, of CO and C1 which are common to all channels.

The Model 4516 can be programmed to perform the functions of single 48-fold or triple 16-fold fan-in, and any combination of AND or OR logic. This ability to achieve a variety of logic functions and to redistribute the input signals via high impedance to subsequent units for other logic purposes makes the Model 4516 a convenient and generally useful component of today's demanding trigger systems.

SPECIFICATIONS

Input Characteristics

Number of Channels: 16, all identical.

Logic Inputs:

3, 100 Ohm direct-coupled; high impedance by simple user option. Reflections < 10% for complementary ECL signal of 2 nsec risetime.

Veto:

Rear-panel connector. Permits simultaneous vetoing of all channels. 50 Ohm; requires NIM-level signal (> -600 mV ) direct-coupled. Must overlap coin- cidence of the 3 front panel inputs by a minimum of 5 nsec.

Output Characteristics

Complementary Output:

One per channel. ECL level (-0.8 and -1.6 V). Capable of driving 100 Ohm twisted-pair cable. Duration equal to input overlap. Risetimes and falltimes 2.5 nsec into 100 Ohm termination.

OR Output:

Two rear-panel connectors. Negative-going voltage output at NIM level. Width is identical to the coincidence overlap.

General

Logic Functions:

Fan-in (2 X 24-fold), and any combination of AND and OR coincidence.

Maximum Rate: 150 MHz input and output.

Coincidence Width:

3.5 nsec up, determined by input pulse duration.

Double-Pulse Resolution:

Less than 5 nsec at minimum input width.

Power Requirements:

+ 6 V at 50 mA

-6 V at 1.25 A

CAMAC Commands