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74F191 Up/Down Binary Counter with Preset and Ripple Clock
April 1988 Revised September 2000
74F191 Up/Down Binary Counter with Preset and Ripple Clock
General Description
The 74F191 is a reversible modulo-16 binary counter featuring synchronous counting and asynchronous presetting. The preset feature allows the 74F191 to be used in programmable dividers. The Count Enable input, the Terminal Count output and Ripple Clock output make possible a variety of methods of implementing multistage counters. In the counting modes, state changes are initiated by the rising edge of the clock.
Features
s High-Speed--125 MHz typical count frequency s Synchronous counting s Asynchronous parallel load s Cascadable
Ordering Code:
Order Number 74F191SC 74F191SJ 74F191PC Package Number M16A M16D N16E Package Description 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Logic Symbols
Connection Diagram
IEEE/IEC
(c) 2000 Fairchild Semiconductor Corporation
DS009495
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74F191
Unit Loading/Fan Out
Pin Names CE CP P0-P3 PL U/D Q0-Q3 RC TC Description Count Enable Input (Active LOW) Clock Pulse Input (Active Rising Edge) Parallel Data Inputs Asynchronous Parallel Load Input (Active LOW) Up/Down Count Control Input Flip-Flop Outputs Ripple Clock Output (Active LOW) Terminal Count Output (Active HIGH) U.L. HIGH/LOW 1.0/3.0 1.0/1.0 1.0/1.0 1.0/1.0 1.0/1.0 50/33.3 50/33.3 50/33.3 Input IIH/IIL Output IOH/IOL 20 A/-1.8 mA 20 A/-0.6 mA 20 A/-0.6 mA 20 A/-0.6 mA 20 A/-0.6 mA
-1 mA/20 mA -1 mA/20 mA -1 mA/20 mA
Functional Description
The 74F191 is a synchronous up/down 4-bit binary counter. It contains four edge-triggered flip-flops, with internal gating and steering logic to provide individual preset, count-up and count-down operations. Each circuit has an asynchronous parallel load capability permitting the counter to be preset to any desired number. When the Parallel Load (PL) input is LOW, information present on the Parallel Data inputs (P0-P3) is loaded into the counter and appears on the Q outputs. This operation overrides the counting functions, as indicated in the Mode Select Table. A HIGH signal on the CE input inhibits counting. When CE is LOW, internal state changes are initiated synchronously by the LOW-to-HIGH transition of the clock input. The direction of counting is determined by the U/D input signal, as indicated in the Mode Select Table. CE and U/D can be changed with the clock in either state, provided only that the recommended setup and hold times are observed. Two types of outputs are provided as overflow/underflow indicators. The Terminal Count (TC) output is normally LOW and goes HIGH when a circuit reaches zero in the count-down mode or reaches 15 in the count-up mode. The TC output will then remain HIGH until a state change occurs, whether by counting or presetting or until U/D is changed. The TC output should not be used as a clock signal because it is subject to decoding spikes. The TC signal is also used internally to enable the Ripple Clock (RC) output. The RC output is normally HIGH. When CE is LOW and TC is HIGH, the RC output will go LOW when the clock next goes LOW and will stay LOW until the clock goes HIGH again. This feature simplifies the design of multistage counters, as indicated in Figure 1 and Figure 2. In Figure 1, each RC output is used as the clock input for the next higher stage. This configuration is particularly advantageous when the clock source has a limited drive capability, since it drives only the first stage. To prevent counting in all stages it is only necessary to inhibit the first stage, since a HIGH signal on CE inhibits the RC output pulse, as indicated in the RC Truth Table. A disadvantage of this configuration, in some applications, is the timing skew between state changes in the first and last stages. This represents the cumulative delay of the clock as it ripples through the preceding stages. A method of causing state changes to occur simultaneously in all stages is shown in Figure 2. All clock inputs are driven in parallel and the RC outputs propagate the carry/borrow signals in ripple fashion. In this configuration the LOW state duration of the clock must be long enough to www.fairchildsemi.com 2 allow the negative-going edge of the carry/borrow signal to ripple through to the last stage before the clock goes HIGH. There is no such restriction on the HIGH state duration of the clock, since the RC output of any device goes HIGH shortly after its CP input goes HIGH. The configuration shown in Figure 3 avoids ripple delays and their associated restrictions. The CE input for a given stage is formed by combining the TC signals from all the preceding stages. Note that in order to inhibit counting an enable signal must be included in each carry gate. The simple inhibit scheme of Figure 1 and Figure 2 doesn't apply, because the TC output of a given stage is not affected by its own CE.
Mode Select Table
Inputs PL H H L H CE L L X H U/D L H X X CP Count Up Count Down Preset (Asyn.) No Change (Hold)

X X
Mode
RC Truth Table
Inputs CE L H X TC* H X L Output

CP X X

H H
RC
*TC is generated internally H = HIGH Voltage Level L = LOW Voltage Level X = Immaterial = LOW-to-HIGH Clock Transition = LOW Pulse

74F191
FIGURE 1. n-Stage Counter Using Ripple Clock
FIGURE 2. Synchronous n-Stage Counter Using Ripple Carry/Borrow
FIGURE 3. Synchronous n-Stage Counter with Gated Carry/Borrow
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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74F191
Absolute Maximum Ratings(Note 1)
Storage Temperature Ambient Temperature under Bias Junction Temperature under Bias VCC Pin Potential to Ground Pin Input Voltage (Note 2) Input Current (Note 2) Voltage Applied to Output in HIGH State (with VCC = 0V) Standard Output 3-STATE Output Current Applied to Output in LOW State (Max) twice the rated IOL (mA)
-65C to +150C -55C to +125C -55C to +150C -0.5V to +7.0V -0.5V to +7.0V -30 mA to +5.0 mA
Recommended Operating Conditions
Free Air Ambient Temperature Supply Voltage 0C to +70C
+4.5V to +5.5V
-0.5V to VCC -0.5V to +5.5V
Note 1: Absolute maximum ratings are values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied. Note 2: Either voltage limit or current limit is sufficient to protect inputs.
DC Electrical Characteristics
Symbol VIH VIL VCD VOH VOL IIH IBVI ICEX VID IOD Parameter Input HIGH Voltage Input LOW Voltage Input Clamp Diode Voltage Output HIGH Voltage Output LOW Voltage Input HIGH Current Input HIGH Current Breakdown Test Output HIGH Leakage Current Input Leakage Test Output Leakage Circuit Current IIL IOS ICC Input LOW Current Output Short-Circuit Current Power Supply Current -60 38 4.75 3.75 -0.6 -1.8 -150 55 10% VCC 5% VCC 10% VCC 2.5 2.7 0.5 5.0 7.0 50 Min 2.0 0.8 -1.2 Typ Max Units V V V V V A A A V A Min Min Min Max Max Max 0.0 0.0 VCC Conditions Recognized as a HIGH Signal Recognized as a LOW Signal IIN = -18 mA IOH = -1 mA IOH = -1 mA IOL = 20 mA VIN = 2.7V VIN = 7.0V VOUT = VCC IID = 1.9 A, All Other Pins Grounded VIOD = 150 mV All Other Pins Grounded VIN = 0.5V (except CE) VIN = 0.5V (CE) VOUT = 0V
mA mA mA
Max Max Max
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74F191
AC Electrical Characteristics
TA = +25C Symbol Parameter Min fMAX tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL Maximum Count Frequency Propagation Delay CP to Qn Propagation Delay CP to TC Propagation Delay CP to RC Propagation Delay CE to RC Propagation Delay U/D to RC Propagation Delay U/D to TC Propagation Delay Pn to Qn Propagation Delay PL to Qn Propagation Delay Pn to TC Propagation Delay Pn to RC Propagation Delay PL to TC Propagation Delay PL to RC 100 3.0 5.0 6.0 5.0 3.0 3.0 3.0 3.0 7.0 5.5 4.0 4.0 3.0 6.0 5.0 5.5 5.0 6.5 6.5 6.0 8.0 6.0 10.0 9.0 VCC = +5.0V CL = 50 pF Typ 125 5.5 8.5 10.0 8.5 5.5 5.0 5.0 5.5 11.0 9.0 7.0 6.5 4.5 10.0 8.5 9.0 7.5 11.0 13.0 11.0 7.5 7.0 7.0 7.0 18.0 12.0 10.0 10.0 7.0 13.0 11.0 12.0 14.0 13.0 19.0 14.0 16.5 13.5 20.0 15.5 Max TA = -55C to +125C VCC = +5.0V CL = 50 pF Min 75 3.0 5.0 6.0 5.0 3.0 3.0 3.0 3.0 7.0 5.5 4.0 4.0 3.0 6.0 5.0 5.5 9.5 13.5 16.5 13.5 9.5 9.0 9.0 9.0 22.0 14.0 13.5 12.5 9.0 16.0 13.0 14.5 Max TA = 0C to +70C VCC = +5.0V CL = 50 pF Min 90 3.0 5.0 6.0 5.0 3.0 3.0 3.0 3.0 7.0 5.5 4.0 4.0 3.0 6.0 5.0 5.5 5.0 6.0 6.5 6.0 8.0 6.0 10.0 9.0 8.5 12.0 14.0 12.0 8.5 8.0 8.0 8.0 20.0 13.0 11.0 11.0 8.0 14.0 12.0 13.0 15.0 14.0 20.0 15.0 17.5 14.5 21.0 16.0 ns ns ns ns ns ns ns ns ns Max MHz Units
AC Operating Requirements
TA = +25C Symbol Parameter VCC = +5.0V Min tS(H) tS(L) tH(H) tH(L) tS(L) tH(L) tS(H) tS(L) tH(H) tH(L) tW(L) tW(L) tREC Setup Time, HIGH or LOW Pn to PL Hold Time, HIGH or LOW Pn to PL Setup Time LOW CE to CP Hold Time LOW CE to CP Setup Time, HIGH or LOW U/D to CP Hold Time, HIGH or LOW U/D to CP PL Pulse Width LOW CP Pulse Width LOW Recovery Time PL to CP 4.5 4.5 2.0 2.0 10.0 0 12.0 12.0 0 0 6.0 5.0 6.0 Max TA = -55C to +125C VCC = +5.0V Min 6.0 6.0 2.0 2.0 10.5 0 12.0 12.0 0 0 8.5 7.0 7.5 Max TA = 0C to +70C VCC = +5.0V Min 5.0 5.0 2.0 2.0 10.0 ns 0 12.0 12.0 0 0 6.0 5.0 6.0 ns ns ns ns ns Max Units
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74F191
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Package Number M16A
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74F191
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide Package Number M16D
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74F191 Up/Down Binary Counter with Preset and Ripple Clock
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. LIFE SUPPORT POLICY FAIRCHILD'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 FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. www.fairchildsemi.com 8 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com

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