Order Number DM54LSJ, DM54LSW, DM74LSWM or DM74LSN. See Package Number J20A, M20B, N20A or W20A 2. Download Fairchild Semiconductor DM74LSN pdf datasheet file. DM74LSN Octal D-type Transparent Latches And Edge-triggered Flip-flops DM74LS Details, datasheet, quote on part number: DM74LSN.

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The works reference is:. The digitiser data board was designed, developed, fabricated and tested by the author.

Stock/Availability for: DM74LSO2N

The sign of the output of the integrator is detected by dataseet comparator, the output of which is written onto one bit of a 64 bit data register comprising a D-type latch. BANK – signal common to each of the data boards from the control board – pulses low for a period determined by data transfer rate of control board, and changes at twice the rate of FINGER. A 27k resistor R5 is in series with the output of the comparator to protect the input of the following stage, since the comparator output switches down to the V rail.

The digital signal is finally staticized by U7, 74LS This comprises a 2M resistor package RA1A, and 0.

54LS374 Datasheet PDF

All digital grounds are linked to this plane. Nearby C, there are two diodes D1, and D2.

Following manufacturers’ dm74ls374b, each ACF integrator is decoupled from datasneet rails by 1. The schematic circuit was drawn using OrCAD software. This power rail separation is to reduce power born noise. There are nine data boards in the crate supplied, thus allowing up to channels to be digitised. Full circuit details and user instructions for the control board are in a separate document. Failure to do this could result in data bus contention.


There is considerable decoupling throughout the board. The two unused controls are pulled high by resistors R1 and R2. These are wired back to back between the two ground levels. After testing the data boards out of the crate, it is important to put these switches back to the ‘Normal’ settings, as illustrated in figure 2 below, before reinserting into the crate. This IC is a quad programmable comparator selected for its low and repeatable input offset voltages.

The typical current requirements are:. The function of this filter is to block DC signals and to control the overall sensitivity of the integrator. The dm74l374n fed onto dm74ks374n edge connector is passed directly through the high pass filter.

This would reduce the gain.

datasgeet Before each integration commences, the switch is closed to discharge the integration capacitor, C2. The integration period is determined by the separate control board. If the signal is more positive than this level, the output will switch low and if more negative, it will switch high. It is a modification datasueet a previous design of The output of the comparator is open collector and is thus virtually isolated from the input terminals.


An integration is then performed across a precision pF capacitor for a single sample interval. These boards were developed for use in Pulsar research.

These capacitors are identified on the data board and in the schematic as C through C Refer to the complete schematic diagram at the end of this section.

This documentation concerns the 64 channel Digitiser Data Dm74lss374n designed in The signal is passed through a 0. This reads data from each board and writes the data to a computer interface along with a count word.

Each comparator package is decoupled from both power rails by 10nF capacitors. They are provided to facilitate board testing.

74LS Datasheet catalog

When the operation is complete, the switch is closed for 2us, discharging the capacitor. The shielding is provided by the partial groundplane on the component side of the board. There is a separate regulator for the digital Vcc, U The file is in the same archive, under:.

Test Switches There are two switches on the board selected by jumpers. This was required due to the obsolescence of the comparators previously used. To describe the operation of the circuit, channel 1 is used as an example.