54LS168 Synchronous Bi-Directional BCD Decade Counter General Description The 54LS168 is a fully synchronous 4-state up/down counter featuring a preset capability for programmable operation, carry lookahead for easy cascading and a U/D input to control the direction of counting. It counts in the BCD (8421) sequence and all state changes, whether in counting or parallel loading, are initiated by the LOW-to-HIGH transition of the clock. Connection Diagram Logic Symbol Dual-In-Line Package TL/F/10207 – 1 TL/F/10207 – 2 Order Number 54LS168DMQB, 54LS168FMQB or 54LS168LMQB See NS Package Number E20A, J16A or W16A Pin Names CEP CET CP P0–P3 PE U/D Q0–Q3 TC C1995 National Semiconductor Corporation TL/F/10207 VCC e Pin 16 GND e Pin 8 Description Count Enable Parallel Input (Active LOW) Count Enable Trickle Input (Active LOW) Clock Pulse Input (Active Rising Edge) Parallel Data Inputs Parallel Enable Input (Active LOW) Up-Down Count Control Input Flip-Flop Outputs Terminal Count Output (Active LOW) RRD-B30M105/Printed in U. S. A. 54LS168 Synchronous Bi-Directional BCD Decade Counter June 1989 Absolute Maximum Ratings (Note) Note: The ‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the ‘‘Electrical Characteristics’’ table are not guaranteed at the absolute maximum ratings. The ‘‘Recommended Operating Conditions’’ table will define the conditions for actual device operation. If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage 7V Input Voltage 5.5V Operating Free Air Temperature Range b 55§ C to a 125§ C 54LS b 65§ C to a 150§ C Storage Temperature Range Recommended Operating Conditions Symbol 54LS168 Parameter Units Min Nom Max 4.5 5 5.5 VCC Supply Voltage VIH High Level Input Voltage VIL Low Level Input Voltage IOH High Level Output Current IOL Low Level Output Current TA Free Air Operating Temperature ts (H) ts (L) Setup Time HIGH or LOW Pn, CEP or CET to CP 15 15 ns th (H) th (L) Hold Time HIGH or LOW Pn, CEP or CET to CP 5 5 ns ts (H) ts (L) Setup Time HIGH or LOW PE to CP 20 20 ns th (H) th (L) Hold Time HIGH or LOW PE to CP 0 0 ns ts (H) ts (L) Setup Time HIGH or LOW U/D to CP 25 25 ns th (H) th (L) Hold Time HIGH or LOW U/D to CP 0 0 ns tw (H) tw (L) CP Pulse Width HIGH or LOW 20 20 ns 2 b 55 2 V V 0.7 V b 0.4 mA 4 mA 125 §C Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions VI Input Clamp Voltage VCC e Min, II e b18 mA VOH High Level Output Voltage VCC e Min, IOH e Max, VIL e Max, VIH e Min VOL Low Level Output Voltage VCC e Min, IOL e Max, VIH e Min, VIL e Max II Input Current @ Max Input Voltage VCC e Max, VI e 10.0V IIH High Level Input Current VCC e Max, VI e 2.7V IIL Low Level Input Current IOS ICC VCC e Max, VI e 0.5V Short Circuit Output Current VCC e Max (Note 2) Supply Current VCC e Max (Note 3) Typ (Note 1) Min Max Units b 1.5 V 2.5 V 0.4 V 0.1 mA Inputs 20 CET 40 mA Data b 0.5 b 400 CP, PE, U/D, CEP b 30 b 400 CET b 60 b 800 b 20 b 100 mA 34 mA 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: ICC is measured with all outputs open and all inputs grounded. Switching Characteristics VCC e a 5.0V, TA e a 25§ C (See Section 1 for test waveforms and output load) 54LS168 Symbol Parameter CL e 15 pF Min Units Max fMax Maximum Clock Frequency 25 tPLH tPHL Propagation Delay CP to Qn 20 20 ns tPLH tPHL Propagation Delay CP to TC 30 30 ns tPLH tPHL Propagation Delay CET to TC 15 20 ns tPLH tPHL Propagation Delay U/D to TC 25 25 ns 3 MHz mA Functional Description The ’LS168 uses edge-triggered D-type flip-flops and has no constraints on changing the control or data input signals in either state of the Clock. The only requirement is that the various inputs attain the desired state at least a setup time before the rising edge of the clock and remain valid for the recommended hold time thereafter. The parallel load operation takes precedence over the other operations, as indicated in the Mode Select Table. When PE is LOW, the data on the P0 – P3 inputs enters the flip-flops on the next rising edge of the Clock. In order for counting to occur, both CEP and CET must be LOW and PE must be HIGH. The U/D input then determines the direction of counting. The Terminal Count (TC) output is normally HIGH and goes LOW, provided that CET is LOW, when a counter reaches zero in the COUNT DOWN mode or reaches 9 in the COUNT UP mode. The TC output state is not a function of the Count Enable Parallel (CEP) input level. The TC output of the ’LS168 decade counter can also be LOW in the illegal states 11, 13 and 15, which can occur when power is turned on or via parallel loading. If an illegal state occurs, the ’LS168 will return to the legitimate sequence within two counts. Since the TC signal is derived by decoding the flipflop states, there exists the possibility of decoding spikes on TC. For this reason the use of TC as a clock signal is not recommended (see logic equation below). 1. Count Enable e CEP # CET # PE ’LS168 Mode Select Table PE CEP CET U/D L H H H H X L L H X X L L X H X H L X X Action on Rising Clock Edge Load (Pn x Qn) Count Up (Increment) Count Down (Decrement) No Change (Hold) No Change (Hold) H e HIGH Voltage Level L e LOW Voltage Level X e Immaterial State Diagram 2. Up: TC e Q0 # Q3 # (U/D) # CET 3. Down: TC e Q0 # Q1 # Q2 # Q3 # (U/D) # CET TL/F/10207 – 3 Logic Diagram TL/F/10207 – 4 4 Physical Dimensions inches (millimeters) Ceramic Leadless Chip Carrier Package (E) Order Number 54LS168LMQB NS Package Number E20A 16-Lead Ceramic Dual-In-Line Package (J) Order Number 54LS168DMQB NS Package Number J16A 5 54LS168 Synchronous Bi-Directional BCD Decade Counter Physical Dimensions inches (millimeters) (Continued) 16-Lead Ceramic Flat Package (W) Order Number 54LS168FMQB NS Package Number W16A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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