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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These are dm74ls3374n back to back between the two ground levels. There are nine data boards in the crate supplied, thus allowing up dm74lz374n channels to be digitised. Each comparator package is decoupled from both power rails by 10nF capacitors.
This is to supplement an incomplete track. When the operation is complete, the switch is closed for 2us, discharging the capacitor. This is a low noise dual switched integrator that has a built in precision pF capacitor for integration.
These capacitors are identified on the data board and in the schematic as C through C This documentation concerns the 64 channel Digitiser Data Boards designed in It is a modification to a previous design of This power rail separation is to reduce power born noise. Manufacturers of the board were Precision Engineering Products Chesterton Ltd, who will retain the production artwork for a limited time.
There is considerable decoupling throughout the board. If the signal is more positive than this level, the output will switch low and if more negative, it will switch high. This comprises a 2M resistor package RA1A, and 0. This IC is a quad programmable comparator selected for its low and repeatable input offset voltages.
This is made up of a network of tracks over the board. The output of the comparator is open collector and is thus virtually isolated from the input terminals. The integration period is determined by the separate control board.
Failure to do this could result in data bus contention. This is an octal D-type flip flop with tri-state outputs.
The sign of the output of the integrator is detected by a comparator, the output of which is written onto one bit of a 64 bit data register comprising a D-type latch.
Test Switches There are two switches on the board selected by jumpers. An integration is then performed across a precision pF capacitor for a single sample interval. Full circuit details and user instructions for the control board are in a separate document.
The signal is passed through a 0.
DM74LS374N 数据手册 ( 数据表 ) – Fairchild Semiconductor
Before each integration commences, the switch is closed to discharge the integration capacitor, C2. The schematic circuit was drawn using OrCAD software.
Secondly, the component pads adjacent to the ACF packages allow for the addition of a capacitor in parallel to the internal pF. Dwtasheet typical current requirements are:.
Dm4ls374n function of this filter is to block DC signals and to control the overall sensitivity of the integrator. 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. The file is in the same archive, under:.
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. They are provided to facilitate board testing. Refer to the complete schematic diagram at the end of this section. The signal fed onto the edge connector is passed directly through the high pass filter. The operation is identical for all 64 channels.
This would reduce the gain. 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. There is a separate regulator for the digital Vcc, U The shielding is provided by the partial groundplane on the component side datasheft the board. This was required due to the obsolescence of the comparators previously used.
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To describe the operation of the circuit, channel 1 is used as an example. All digital grounds are linked to this plane. This reads data from each board and writes the data to a computer interface along with a count word. The two datadheet controls are pulled high by resistors R1 and R2. These boards are controlled by one Control Board in the same crate.
Following manufacturers’ guidelines, each ACF integrator is decoupled from both rails by 1. The digitiser data board was designed, developed, fabricated and dm774ls374n by the author.
Nearby C, there are two diodes D1, and D2. The works reference is:.
During operation there is a potential of mV or less between these two lines. The digital signal is finally staticized by U7, 74LS These boards were developed for use in Pulsar research.