SN74LS390 Dual 4-Bit Decade Counters |

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Dual 4-Bit Decade Counters

Dual 4-Bit Decade Counters - SN74LS390


Each of these monolithic circuits contains eight master-slave flip-flops and additional gating to implement two individual four-bit counters in a single package. The '390 and 'LS390 incorporate dual divide-by-two and divide-by-five counters, which can be used to implement cycle lengths equal to any whole and/or cumulative multiples of 2 and/or 5 up to divide-by-100. When connected as a bi-quinary counter, the separate divide-by-two circuit can be used to provide symmetry (a square wave) at the final output stage. The '393 and 'LS393 each comprise two independent four-bit binary counters each having a clear and a clock input. N-bit binary counters can be implemented with each package providing the capability of divide-by-256. The '390, 'LS390, '393, and 'LS393 have parallel outputs from each counter stage so that any submultiple of the input count frequency is available for system-timing signals. Series 54 and Series 54LS circuits are characterized for operation over the full military temperature range of -55°C to 125°C; Series 74 and Series 74LS circuits are characterized for operation from 0°C to 70°C.



  • Dual Versions of the Popular '90A, 'LS90 and '93A, 'LS93
  • '390, 'LS390 … Individual Clocks for A and B Flip-Flops Provide Dual ÷ 2 and ÷ 5 Counters
  • '393, 'LS393 … Dual 4-Bit Binary Counter with Individual Clocks
  • All Have Direct Clear for Each 4-Bit Counter
  • Dual 4-Bit Versions Can Significantly Improve System Densities by Reducing Counter Package Count by 50%
  • Typical Maximum Count Frequency … 35 MHz
  • Buffered Outputs Reduce Possibility of Collector Commutation



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Part number Order Technology Family VCC (Min) (V) VCC (Max) (V) Bits (#) Voltage (Nom) (V) F @ nom voltage (Max) (MHz) ICC @ nom voltage (Max) (mA) tpd @ nom Voltage (Max) (ns) IOL (Max) (mA) IOH (Max) (mA) Function Type Rating Operating temperature range (C) Package Group
SN74LS390 Order now LS     4.75     5.25     4     5     35     26     60     8     -0.4     Counter     Decade     Catalog     0 to 70     PDIP | 16
SOIC | 16
SO | 16    
SN54LS390 Samples not available LS     4.75     5.25     4     5     35     26     60     8     -0.4     Counter     Decade     Military     -55 to 125     CDIP | 16
CFP | 16
LCCC | 20