DM74LS122 datasheet(3/6 Pages) NSC

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Switching Characteristics at VCC e 5V and TA e 25 C (See Section 1 for Test Waveforms and Output Load)

RL e 2kX

Symbol

Parameter

From (Input)

CL e 15 pF

Units

To (Output)

CEXT e 0 pF REXT e 5kX

CEXT e 1000 pF REXT e 10 kX

Min

Max

Min

Max

tPLH

Propagation Delay Time

A to Q

Low to High Level Output

tPLH

Propagation Delay Time

B to Q

Low to High Level Output

tPHL

Propagation Delay Time

A to Q

High to Low Level Output

tPHL

Propagation Delay Time

B to Q

High to Low Level Output

tPLH

Propagation Delay Time

Clear to Q

Low to High Level Output

tPHL

Propagation Delay Time

Clear to Q

High to Low Level Output

tWQ(Min)

Minimum Width of Pulse

A or B to Q

200

at Output Q

tW(out)

Output Pulse Width

A or B to Q

Note 1

All typicals are at VCC e 5V TA e 25 C

Note 2

Not more than one output should be shorted at a time and the duration should not exceed one second

Note 3

Quiescent ICC is measured (after clearing) with 24V applied to all clear and A inputs B inputs grounded all outputs open CEXT e 002 mF and REXT e

25 kX

Note 4

ICC is measured in the triggered state with 24V applied to all clear and B inputs A inputs grounded all outputs open CEXT e 002 mF and REXT e 25 kX

Note 5

With all outputs open and 45V applied to all data and clear inputs ICC is measured after a momentary ground then 45V is applied to the clock

Note 6

TA e 25 C and VCC e 5V

Operating Rules

1 To use the internal 10 kX timing resistor connect the

RINT pin to VCC

2 An external resistor (RX) or the internal resistor (10 kX)

and an external capacitor (CX) are required for proper

operation The value of CX may vary from 0 to any neces-

sary value For small time constants use high-quality

mica glass polypropylene polycarbonate or polystyrene

capacitors For large time constants use solid tantalum or

special aluminum capacitors If the timing capacitors

have leakages approaching 100 nA or if stray capaci-

tance from either terminal to ground is greater than 50 pF

the timing equations may not represent the pulse width

the device generates

3 The pulse width is essentially determined by external tim-

ing components RX and CX For CX k 1000 pF see Fig-

ure 1 design curves on TW as function of timing compo-

nents value For CX ll 1000 pF the output is defined as

TW e KRXCX

where RX is in kX

CX is in pF

TW is in ns

037

TLF6385 – 2

FIGURE 1

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