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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Before each integration commences, the switch is closed to discharge the integration capacitor, C2. Each comparator package is decoupled from both power rails by 10nF capacitors.
Secondly, the component pads adjacent to the ACF packages allow for the addition of a capacitor in parallel to the internal pF. The typical current requirements are:.
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This is an octal D-type flip flop with tri-state outputs. All digital grounds are linked to this plane.
To describe the operation of the circuit, channel 1 is used as an example. This is to supplement an incomplete track.
There is considerable decoupling throughout the board. The integration period is determined by the separate control board.
54LS374 Datasheet PDF
An integration is then performed across a precision pF capacitor for a single sample interval. The works reference is:. These capacitors are identified on dmm74ls374n data board dm74,s374n in the schematic as C through C Refer to the complete schematic diagram at the end of this section. 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.
This comprises a 2M resistor package RA1A, and 0.
DM74LSN Datasheet PDF – National ->Texas Instruments
This power rail separation is to reduce power born noise. The digital signal is finally staticized by U7, 74LS The operation is identical for all 64 channels. Dm74ls37n4 IC is a quad programmable comparator selected for its low and repeatable input offset voltages.
Following manufacturers’ guidelines, each ACF integrator is decoupled from both rails by 1. 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. If the signal is more positive than this level, the output will switch low and if more negative, it will switch high.
The signal is passed through a 0. There are nine data boards in the crate supplied, thus allowing up to channels to be digitised. It is a modification to a previous design of Failure to do this could result in adtasheet bus contention. This is a low noise dual switched integrator that has a built in precision pF capacitor for integration. The schematic circuit was drawn using OrCAD software. There is a separate regulator for the digital Vcc, U This documentation concerns the 64 channel Digitiser Data Boards designed in This would reduce the gain.
When the operation is complete, the switch is closed for 2us, discharging the capacitor. These boards are controlled by one Control Board in the same crate. Full circuit details and user instructions for the control board are in a separate document.
This reads data from each board and writes the data to a computer interface along with a count word. The signal fed onto the edge connector is passed directly rm74ls374n the high pass filter. Manufacturers of the board were Precision Engineering Products Chesterton Ltd, who will retain the production artwork for a limited time.
This is made up of a network of tracks over the board. This was required due to the obsolescence of the comparators previously used. The two unused controls are pulled high by resistors R1 and R2. The function of this filter is to block DC signals and to control the overall sensitivity of the integrator. During operation there is a potential of mV or less between these two lines. They are provided to facilitate board testing. Test Switches There are two switches on the board selected by jumpers.
The digitiser data board was designed, developed, fabricated and tested by the author. Nearby C, there are two diodes D1, and D2. The output of the comparator is open collector and is thus virtually isolated from the input terminals. 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.
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The file is in the same archive, under:. These are wired back to back between the two ground levels. The shielding is provided by the partial groundplane on the component side of the board.