Revised April 2000 DM74LS221 Dual Non-Retriggerable One-Shot with Clear and Complementary Outputs General Description Features The DM74LS221 is a dual monostable multivibrator with Schmitt-trigger input. Each device has three inputs permitting the choice of either leading-edge or trailing-edge triggering. Pin (A) is an active-LOW trigger transition input and pin (B) is an active-HIGH transition Schmitt-trigger input that allows jitter free triggering for inputs with transition rates as slow as 1 volt/second. This provides the input with excellent noise immunity. Additionally an internal latching circuit at the input stage also provides a high immunity to VCC noise. The clear (CLR) input can terminate the output pulse at a predetermined time independent of the timing components. This (CLR) input also serves as a trigger input when it is pulsed with a low level pulse transition ( ). To obtain the best and trouble free operation from this device please read operating rules as well as the Fairchild Semiconductor one-shot application notes carefully and observe recommendations. ■ A dual, highly stable one-shot ■ Compensated for VCC and temperature variations ■ Pin-out identical to DM74LS123 (Note 1) ■ Output pulse width range from 30 ns to 70 seconds ■ Hysteresis provided at (B) input for added noise immunity ■ Direct reset terminates output pulse ■ Triggerable from CLEAR input ■ DTL, TTL compatible ■ Input clamp diodes Note 1: The pin-out is identical to DM74LS123 but, functionally it is not; refer to Operating Rules #10 in this datasheet. Ordering Code: Order Number Package Number Package Description DM74LS221M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow DM74LS221SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide DM74LS221N N16E 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. Connection Diagram Function Table Inputs Outputs CLEAR A B Q Q L X X L H X H X L H X X L H L ↑ H ↓ H L H ↑ (Note 2) H = HIGH Logic Level L = LOW Logic Level X = Can Be Either LOW or HIGH ↑ = Positive Going Transition ↓ = Negative Going Transition = A Positive Pulse = A Negative Pulse L H Note 2: This mode of triggering requires first the B input be set from a LOW-to-HIGH level while the CLEAR input is maintained at logic LOW level. Then with the B input at logic HIGH level, the CLEAR input whose positive transition from LOW-to-HIGH will trigger an output pulse. © 2000 Fairchild Semiconductor Corporation DS006409 www.fairchildsemi.com DM74LS221 Dual Non-Retriggerable One-Shot with Clear and Complementary Outputs August 1986 DM74LS221 Dual Non-Retriggerable One-Shot Functional Description The basic output pulse width is determined by selection of an external resistor (RX) and capacitor (CX). Once triggered, the basic pulse width is independent of further input transitions and is a function of the timing components, or it may be reduced or terminated by use of the active low CLEAR input. Stable output pulse width ranging from 30 ns to 70 seconds is readily obtainable. Operating Rules 8. Duty cycle is defined as tW/T × 100 in percentage, if it goes above 50% the output pulse width will become shorter. If the duty cycle varies between LOW and HIGH values, this causes output pulse width to vary, or jitter (a function of the REXT only). To reduce jitter, REXT should be as large as possible, for example, with REXT = 100k jitter is not appreciable until the duty cycle approaches 90%. 1. 2. An external resistor (RX) and an external capacitor (CX) are required for proper operation. The value of CX may vary from 0 to approximately 1000 µF. For small time constants high-grade mica, glass, polypropylene, polycarbonate, or polystyrene material capacitor may be used. For large time constants use tantalum or special aluminum capacitors. If timing capacitor has leakages approaching 100 nA or if stray capacitance from either terminal to ground is greater than 50 pF the timing equations may not represent the pulse width the device generates. 9. Under any operating condition CX and RX must be kept as close to the one-shot device pins as possible to minimize stray capacitance, to reduce noise pick-up, and to reduce I-R and Ldi/dt voltage developed along their connecting paths. If the lead length from CX to pins (6) and (7) or pins (14) and (15) is greater than 3 cm, for example, the output pulse width might be quite different from values predicted from the appropriate equations. A non-inductive and low capacitive path is necessary to ensure complete discharge of CX in each cycle of its operation so that the output pulse width will be accurate. When an electrolytic capacitor is used for CX a switching diode is often required for standard TTL one-shots to prevent high inverse leakage current. This switching diode is not needed for the DM74LS221 one-shot and should not be used. Furthermore, if a polarized timing capacitor is used on the DM74LS221, the positive side of the capacitor should be connected to the “CEXT” pin (Figure 1). 3. 10. Although the DM74LS221's pin-out is identical to the DM74LS123 it should be remembered that they are not functionally identical. The DM74LS123 is a retriggerable device such that the output is dependent upon the input transitions when its output “Q” is at the “High” state. Furthermore, it is recommended for the DM74LS123 to externally ground the CEXT pin for improved system performance. However, this pin on the DM74LS221 is not an internal connection to the device ground. Hence, if substitution of an DM74LS221 onto an DM74LS123 design layout where the CEXT pin is wired to the ground, the device will not function. For CX >> 1000 pF, the output pulse width (tW) is defined as follows: tW = KRX CX where [RX is in kΩ] [CX is in pF] [tW is in ns] K ≈ Ln2 = 0.70 4. The multiplicative factor K is plotted as a function of CX for design considerations: (See Figure 4). 5. For CX < 1000 pF see Figure 3 for tW vs. CX family curves with RX as a parameter. 6. To obtain variable pulse widths by remote trimming, the following circuit is recommended: (See Figure 2). 7. Output pulse width versus VCC and temperatures: Figure 5 depicts the relationship between pulse width variation versus VCC. Figure 6 depicts pulse width variation versus temperatures. www.fairchildsemi.com 11. VCC and ground wiring should conform to good highfrequency standards and practices so that switching transients on the VCC and ground return leads do not cause interaction between one-shots. A 0.01 µF to 0.10 µF bypass capacitor (disk ceramic or monolithic type) from VCC to ground is necessary on each device. Furthermore, the bypass capacitor should be located as close to the VCC-pin as space permits. 2 (Continued) Note: “Rremote” should be as close to the one-shot as possible. FIGURE 1. FIGURE 2. FIGURE 3. FIGURE 4. FIGURE 5. FIGURE 6. Note: For further detailed device characteristics and output performance, please refer to the Fairchild Semiconductor one-shot application note AN-372. 3 www.fairchildsemi.com DM74LS221 Dual Non-Retriggerable One-Shot Operating Rules DM74LS221 Dual Non-Retriggerable One-Shot Absolute Maximum Ratings(Note 3) Supply Voltage Input Voltage 7V 0°C to +70°C Operating Free Air Temperature Range Storage Temperature Range Note 3: 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 tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation. 7V −65°C to +150°C Recommended Operating Conditions Symbol Parameter VCC Supply Voltage VT+ Positive-Going Input Threshold Voltage Min Nom Max Units 4.75 5 5.25 V 1 2 V at the A Input (VCC = Min) VT− Negative-Going Input Threshold Voltage 0.8 at the A Input (VCC = Min) VT+ Positive-Going Input Threshold Voltage 1 at the B Input (VCC = Min) VT− 1 Negative-Going Input Threshold Voltage 0.8 at the B Input (VCC = Min) V 2 0.9 V V IOH HIGH Level Output Current −0.4 mA IOL LOW Level Output Current 8 mA tW Pulse Width Data 40 (Note 4) Clear 40 tREL Clear Release Time (Note 4) ns 15 ns Rate of Rise or Fall of 1 Schmitt Input (B) (Note 4) Rate of Rise or Fall of 1 Logic Input (A) (Note 4) REXT External Timing Resistor (Note 4) CEXT External Timing Capacitance (Note 4) DC Duty Cycle RT = 2 kΩ 50 (Note 4) RT = REXT (Max) 60 TA Free Air Operating Temperature 100 kΩ 0 1000 µF 0 Note 4: TA = 25°C and VCC = 5V. www.fairchildsemi.com 1.4 4 70 % °C over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions VI Input Clamp Voltage VCC = Min, II = −18 mA VOH HIGH Level VCC = Min, IOH = Max Output Voltage VIL = Max, VIH = Min VOL LOW Level VCC = Min, IOL = Max Output Voltage VIL = Max, VIH = Min Min 2.7 Typ (Note 5) Max Units −1.5 V 3.4 0.35 V 0.5 VCC = Min, IOL = 4 mA 0.4 V II Input Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 mA IIH HIGH Level Input Current VCC = Max, VI = 2.7V 20 µA IIL LOW Level VCC = Max Input Current VI = 0.4V IOS ICC Short Circuit VCC = Max Output Current (Note 6) Supply Current VCC = Max A1, A2 −0.4 B −0.8 Clear −0.8 −20 −100 mA mA Quiescent 4.7 11 Triggered 19 27 Min Max Units 70 ns 55 ns 80 ns 65 ns 65 ns 55 ns 20 70 ns 600 750 ns 6 7.5 ms 70 150 ns mA Note 5: All typicals are at VCC = 5V, TA = 25°C. Note 6: Not more than one output should be shorted at a time, and the duration should not exceed one second. Switching Characteristics at VCC = 5V and TA = 25°C Symbol tPLH Parameter Propagation Delay Time LOW-to-HIGH Level Output tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL tW(out) From (Input) To (Output) Conditions A1, A2 CEXT = 80 pF to Q REXT = 2 kΩ B CL = 15 pF to Q RL = 2 kΩ A1, A2 to Q B to Q Clear to Q Propagation Delay Time Clear HIGH-to-LOW Level Output to Q Output Pulse A1, A2 CEXT = 0 Width Using Zero to Q, Q REXT = 2 kΩ RL = 2 kΩ Timing Capacitance CL = 15 pF tW(out) Output Pulse A1, A2 CEXT = 100 pF Width Using External to Q, Q REXT = 10 kΩ RL = 2 kΩ Timing Resistor CL = 15 pF CEXT = 1 µF REXT = 10 kΩ RL = 2 kΩ CL = 15 pF CEXT = 80 pF REXT = 2 kΩ RL = 2 kΩ CL = 15 pF 5 www.fairchildsemi.com DM74LS221 Dual Non-Retriggerable One-Shot Electrical Characteristics DM74LS221 Dual Non-Retriggerable One-Shot Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Package Number M16A www.fairchildsemi.com 6 DM74LS221 Dual Non-Retriggerable One-Shot Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide Package Number M16D 7 www.fairchildsemi.com DM74LS221 Dual Non-Retriggerable One-Shot with Clear and Complementary Outputs 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: 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. 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 www.fairchildsemi.com 8