NIM Model 688 Level Adapter
* 8 NIM to TTL and 8 TTL to NIM converters
* Direct - coupled
* Full input protection-
* Stage delays typically < 15 ns
* TTL outputs compatible with terminated 50 Ohm cable
* Switchable normal or complementary operation in groups of four
* No duty cycle limitations
* Single - width module

The LRS Model 688 Level Adapter provides 8 channels of direct-coupled NIM to TTL and 8 channels of TTL to NIM conversion in a single-width NIM module.

The NIM to TTL section accepts either normal or complementary NIM logic levels (logical "O"= 0 to -2 mA; logical "l" = -12 to -32 mA) at each of its eight 50 Ohm inputs. The 8 outputs switch between zero volts and + 3.5 volts for a time equal to the input signal duration. The polarity of the outputs is controlled by two front-panel switches common to two groups of four channels and provides either normal or complementary operation. Up to 70 mA at + 3.5 volts is delivered from each output, making the TTL drive capability compatible with terminated, direct-coupled 50 Ohm cable. The low level clamp capability is 100 mA, or approximately 60 standard TTL loads. Direct-coupled, the 688 is free from any rate effects and has no limitations on duty cycle.

The TTL to NIM section accepts standard TTL logic levels (logical "O" = 0 to + .8V; logical "l" = > 2 volts) at each of its eight inputs. The minimum input duration for a full output is 10 ns. The output from each channel is a standard NIM logic level which switches between 0 volts and -16 mA (-800 mV into 50 Ohm ) during an output. Risetimes and falltimes are <4 ns and the output width is equal to the duration of the input signal. Two front-panel switches common to two groups of four channels provides either normal operation (TTL logical "l" IN gives NIM logical "l" OUT) or complementary operation.

SPECIFICATIONS

NIM Model 688 Level Adapter

NIM TO TTL SECTION
NUMBER OF CHANNELS	8
INPUT CHARACTERISTICS
Impedance:	50 Ohm +/- 5%; reflections < 10% for risetime > 2 ns.
Quiescent DC Level:	0 volts.
Input Signal:	Normal (logical "O" = 0 to -2 mA; logical "l" = -12 to -32 mA) or complementary fast NIM logic levels.
Input Protection:	+4 A for 0.5us, clamping at +/-7 volts.
Minimum Input Width:	Less than 5 ns.
OUTPUT CHARACTERISTICS
Signal Levels:	Logical "O" = 0 volts; logical " 1 + 3.5 volts.
High Level Drive Capability:	70 mA (compatible with terminated, direct- coupled 50 Ohm cable.
Low Level Clamp Capability:	Approximately 100 mA at 0 +/-400 mV (approx. 60 standard TTL loads).
Risetime:	Normal, 5 ns; complement, 3 ns.
Falltime:	Normal, 3 ns; complement, 5 ns.
Output Duration:	Equal to input width, FWHM.
Output Impedance:	Less than 5 Ohm
Duty Cycle Limitations:	None.
GENERAL
Delay:	Normal and complement, less than 15 ns.
Logic Polarity:	Two front-panel switches, each common to four channels, provides normal operation (logical "l" IN gives logical "l" OUT) or complementary operation.
TTL TO NIM SECTION
NUMBER OF CHANNELS	8
INPUT CHARACTERISTICS
Input Signal:	Standard TTL logic levels (logical "O" =Oto + .8 volts, logical "l" >2volts).
Maximum Low Level Clamp Current:	- 1.6 mA.
Minimum Input Duration:	Less than 10 ns.
Input Protection:	+5A for 0.5 us,clamping at +/-7volts.
OUTPUT CHARACTERISTICS
Signal Levels:	Logical "O", open circuit; logical "l 16 mA.
Output Duration:	Equal to input duration, FWHM.
Risetime:	Normal, 4 ns; complement, 3 ns.
Falltime:	Normal, 3 ns; complement, 4 ns.
Duty Cycle Limitations:	None.
GENERAL
Delay:	Normal, < 20 ns; complementary, approx. 10 ns.
Logic Polarity:	Two front-panel switches, each common to four channels, provide normal operation (logical "l " IN gives logical "l " OUT) or complementary operation.
MODULE CHARACTERISTICS
Packaging:	NIM single-width module; Lemo-type connectors.
Voltages Required:	+ 6 volts