Page 31 - EE2449_TTL_Datasheet

SN54/74LS90 • SN54/74LS92 • SN54/74LS93

AC CHARACTERISTICS (T A = 25°C, V CC = 5.0 V, C L = 15 pF)
Limits
LS90 LS92 LS93
Symbol Parameter Min Typ Max Min Typ Max Min Typ Max Unit
f MAX CP 0 Input Clock Frequency 32 32 32 MHz
f MAX CP 1 Input Clock Frequency 16 16 16 MHz
t PLH Propagation Delay, 10 16 10 16 10 16 ns
t PHL CP 0 Input to Q 0 Output 12 18 12 18 12 18
t PLH 32 48 32 48 46 70
CP 0 Input to Q 3 Output ns
t PHL 34 50 34 50 46 70
t PLH 10 16 10 16 10 16
CP 1 Input to Q 1 Output ns
t PHL 14 21 14 21 14 21
t PLH 21 32 10 16 21 32
CP 1 Input to Q 2 Output ns
t PHL 23 35 14 21 23 35
t PLH 21 32 21 32 34 51
CP 1 Input to Q 3 Output ns
t PHL 23 35 23 35 34 51
t PLH MS Input to Q 0 and Q 3 Outputs 20 30 ns
t PHL MS Input to Q 1 and Q 2 Outputs 26 40 ns
t PHL MR Input to Any Output 26 40 26 40 26 40 ns
AC SETUP REQUIREMENTS (T A = 25°C, V CC = 5.0 V)
Limits
LS90 LS92 LS93
Symbol Parameter Min Max Min Max Min Max Unit
t W CP 0 Pulse Width 15 15 15 ns
t W CP 1 Pulse Width 30 30 30 ns
t W MS Pulse Width 15 ns
t W MR Pulse Width 15 15 15 ns
t rec Recovery Time MR to CP 25 25 25 ns
RECOVERY TIME (t rec ) is defined as the minimum time required between the end of the reset pulse and the clock transition from HIGH-to-LOW in order to recognize
and transfer HIGH data to the Q outputs
AC WAVEFORMS

*CP 1.3 V 1.3 V 1.3 V
t W
t PHL t PLH
Q 1.3 V 1.3 V
Figure 1
*The number of Clock Pulses required between the t PHL and t PLH measurements can be determined from the appropriate Truth Tables.

MR & MS 1.3 V 1.3 V MS 1.3 V 1.3 V
t W t rec t W t rec
CP 1.3 V CP 1.3 V
t PHL t PLH
Q 0 • Q 3
Q 1.3 V (LS90) 1.3 V
Figure 2 Figure 3

FAST AND LS TTL DATA
5-94
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