74VHC221A Dual Non-Retriggerable Monostable Multivibrator

Transcription

1 221A Dual Non-Retriggerable Monostable Multivibrator General Description The VHC221A is an advanced high speed CMOS Monostable Multivibrator fabricated with silicon gate CMOS technology It achieves the high speed operation similar to equivalent Bipolar Schottky TTL while maintaining the CMOS low power dissipation Each multivibrator features both a negative A and a positive B traition triggered input either of which can be used as an inhibit input Also included is a clear input that when taken low resets the one-shot The VHC221A can be triggered on the positive traition of the clear while A is held low and B is held high The VHC221A is non-retriggerable and therefore cannot be retriggered until the output pulse times out The output pulse width is determined by the equation PW e (Rx)(Cx) where PW is in seconds R is in ohms and C is in farads Limits for R x and C x are External capacitor C x External resistors R x No limit V CC e 2 0V 5 kx min V CC l 3 0V 1 kx min October 1995 An input protection circuit eures that 0 to 7V can be applied to the input pi without regard to the supply voltage This device can be used to interface 5V to 3V systems and two supply systems such as battery back up This circuit prevents device destruction due to mismatched supply and input voltages Features Low Power Dissipation I CC e 4 ma (Max) at T A e 25 C Active State ICC e 600 ma (Max) at T A e 25 C High Noise Immunity VNIH e V NIL e 28% V CC (min) All inputs are equipped with a power down protection function Balanced Propagation Delays tplh j t PHL Pin and function compatible with 74HC221A Commercial Package Number Package Description 221AM M16A 16-Lead Molded JEDEC SOIC 221ASJ M16D 16-Lead Molded EIAJ SOIC 221AMTC MTC16 16-Lead Molded JEDEC Type 1 TSSOP 221AN N16E 16-Lead Molded DIP Note Surface mount packages are also available on Tape and Reel Specify by appending the suffix letter X to the ordering code Logic Symbol Connection Diagram 221A Dual Non-Retriggerable Monostable Multivibrator IEEE IEC Pin Assignment for DIP TSSOP and SOIC TL F TL F C1995 National Semiconductor Corporation TL F RRD-B30M125 Printed in U S A

2 Truth Table Inputs Outputs A B CLR Q Q Function K H H Output Enable X L H L H Inhibit H X H L H Inhibit L L H Output Enable L H L Output Enable X X L L H Reset X Don t Care Block Diagrams TL F TL F Note 1 Cx Rx Dx are external Capacitor Resistor and Diode respectively Note 2 External clamping diode Dx External capacitor is charged to V CC level in the wait state i e when no trigger is applied If the supply voltage is turned off Cx discharges mainly through the internal (parasitic) diode If Cx is sufficiently large and V CC drops rapidly there will be some possibility of damaging the IC through in rush current or latch-up If the capacitance of the supply voltage filter is large enough and V CC drops slowly the in rush current is automatically limited and damage to the IC is avoided The maximum value of forward current through the paracitic diode is g20 ma In the case of a large Cx the limit of fall time of the supply voltage is determined as follows t f t (V CC b0 7) Cx 20 ma (t f is the time between the supply voltage turn off and the supply voltage reaching 0 4 V CC ) In the event a system does not satisfy the above condition an external clamping diode (Dx) is needed to protect the IC from rush current 2

3 System Diagram 221A TL F

4 Timing Chart 221A TL F Functional Description 1 Stand-by State The external capacitor (Cx) is fully charged to V CC in the Stand-by State That mea before triggering the Q P and Q N traistors which are connected to the Rx Cx node are in the off state Two comparators that relate to the timing of the output pulse and two reference voltage supplies turn off The total supply current is only leakage current 2 Trigger Operation Trigger operation is effective in any of the following three cases First the condition where the A input is low and B input has a rising signal second where the B input is high and the A input has a falling signal and third where the A input is low and the B input is high and the CLR input has a rising signal After a trigger becomes effective comparators C1 and C2 start operating and Q N is turned on The external capacitor discharges through Q N The voltage level at the Rx Cx node drops If the Rx Cx voltage level falls to the internal reference voltage V ref L the output of C1 becomes low The flip-flop is then reset and Q N tur off At that moment C1 stops but C2 continues operating After Q N tur off the voltage at the Rx Cx node starts rising at a rate determined by the time cotant of external capacitor Cx and resistor Rx Upon triggering output Q becomes high following some delay time of the internal F F and gates It stays high even if the voltage of Rx Cx changes from falling to rising When Rx Cx reaches the internal reference voltage V ref H the output of C2 becomes low the output Q goes low and C2 stops its operation That mea after triggering when the voltage level of the Rx Cx node reaches V ref H the IC retur to its MONOSTABLE state With large values of Cx and Rx and ignoring the discharge time of the capacitor and internal delays of the IC the width of the output pulse t W (OUT) is as follows t W (OUT) e 1 0 Cx Rx 3 Reset Operation In normal operation the CLR input is held high If CLR is low a trigger has no affect because the Q output is held low and the trigger control F F is reset Also Q p tur on and Cx is charged rapidly to V CC This mea if CLR is set low the IC goes into a wait state 4

5 Absolute Maximum Ratings (Note 1) Supply Voltage (V CC ) b0 5V to a7 0V DC Input Voltage (V IN ) b0 5V to a7 0V DC Output Voltage (V OUT ) b0 5 to V CC a0 5V Input Diode Current (I IK ) b20 ma Output Diode Current (I OK ) g20 ma DC Output Current (I OUT ) g25 ma DC V CC Current (I CC ) g50 ma Storage Temperature (T STG ) b65 Cto150 C Lead Temperature (T L ) Soldering 10 sec 260 C Note 1 Absolute maxmimum ratings are values beyond which the device may be damaged or have its useful life impaired The databook specificatio should be met without exception to eure that the system design is reliable over its power supply temperature and output input loading variables National does not recommended operation outside data book specificatio DC Characteristics for VHC Family Devices Recommended Operating Conditio Supply Voltage (V CC ) Input Voltage (V IN ) Output Voltage (V OUT ) Operating Temperature (T opr ) Input Rise and Fall Time (t r t f ) (CLR only) V CC e 3 3V g0 3V V CC e 5 0V g0 5V External Capacitor - Cx External Resistor - Rx Symbol Parameter V CC (V) T A e 25 C T A eb40 to 85 C Min Typ Max Min Max V IH High Level Input Voltage V CC 0 7 V CC V IL Low Level Input Voltage V CC 0 3 V CC 2 0V to a5 5V 0Vto a5 5V 0VtoV CC b40 to a85 C 0 E 100 V 0 E 20 V No Limitation F l5kx (V CC e 2 0V) l1kx (V CC l 3 0V) The maximum allowable values of Cx and Rx are a function of the leakage of capacitor Cx the leakage of the device and leakage due to board layout and surface resistance Susceptibility to externally induced noise signals may occur for Rxl 1MX Units V V Conditio V OH High Level V IN e V IH I OH eb50 ma Output Voltage V or V IL I V OH eb4ma I OH eb8ma V OL Low Level V IN e V IH I OL e 50 ma Output Voltage or V IL V I OL e 4mA I OL e 8mA I IN Input Leakage Current g0 1 g1 0 ma V IN e 5 5V or GND I IN Rx Cx Terminal g2 50 V 5 5 g0 25 ma IN e V CC or GND Off-State Current I CC Quiescent Supply Current ma V IN e V CC or GND I CC Active State V IN e V CC or GND Supply Current ma Rx Cx e 0 5 V CC Per Circuit 5

6 AC Electrical Characteristics for VHC Family Devices Symbol Parameter V CC (V) T A e T 25 C A eb40 C to a85 C Min Typ Max Min Max t PLH Propagation Delay Time C 3 3 g 0 3 L e 15 pf t PHL (A B Q Q) CL e 50 pf t PLH Propagation Delay Time t PHL (CLR Trigger Q Q) t PLH Propagation Delay Time t PHL (CLR Q Q) 5 0 g g g g g 0 5 Units C L e 15 pf C L e 50 pf C L e 15 pf C L e 50 pf C L e 15 pf C L e 50 pf C L e 15 pf C L e 50 pf C L e 15 pf C L e 50 pf Conditio t WOUT Output Pulse Width C X e 28 pf 3 3 g C L e 50 pf R X e 6kX 5 0 g g C L e 50 pf Cx e 28 pf 5 0 g Rx e 2kX 3 3 g ms C L e 50 pf Cx e 0 01 mf 5 0 g Rx e 10 kx 3 3 g ms C L e 50 pf Cx e 0 1 mf 5 0 g Rx e 10 kx Dt wout Output Pulse Width Error Between Circuits g1 % (In same Package) C IN Input Capacitance pf V CC e Open C PD Power Dissipation (Note 1) 73 pf Capacitance Note 1 C PD is defined as the value of the internal equivalent capacitance which is calculated from the operating current coumption without load Average operating current can be obtained by the equation I CC (opr ) e C PD V CC f INa I CC 1 Duty 100 a I CC 2 (per Circuit) I CC 1 Active Supply Current Duty % Refer to 221A Timing Chart AC Operating Requirement Symbol Parameter V CC (V) T A e T 25 C A eb40 C to a85 C Min Typ Max Min Max t W (L) Minimum Trigger t W (H) Pulse Width t W (L) Minimum Clear Pulse Width Units Conditio 6

7 Device Characteristics t wout C x Characteristics (typ) Input Equivalent Circuit TL F TL F Output Pulse Width Cotant K-Supply Voltage (Typical) TL F Ordering Information The device number is used to form part of a simplified purchasing code where the package type and temperature range are defined as follows TL F

8 Physical Dimeio inches (millimeters) 16-Lead Small Outline Integrated Circuit JEDEC (M) Order Number 221AM or 221AMX NS Package Number M16A 16-Lead Small Outline Package-EIAJ (SJ) Order Number 221ASJ or 221ASJX NS Package Number M16D 8

9 Physical Dimeio inches (millimeters) (Continued) 16-Lead Plastic JEDEC TSSOP Type I (MTC) Order Number 221AMTC or 221AMTCX NS Package Number MTC16 9

10 221A Dual Non-Retriggerable Monostable Multivibrator Physical Dimeio inches (millimeters) (Continued) 16-Lead (0 300 Wide) Molded Dual-In-Line Package (P) Order Number 221AN NS Package Number N16E LIFE SUPPORT POLIC NATIONAL S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION As used herein 1 Life support devices or systems are devices or 2 A critical component is any component of a life systems which (a) are intended for surgical implant support device or system whose failure to perform can into the body or (b) support or sustain life and whose be reasonably expected to cause the failure of the life failure to perform when properly used in accordance support device or system or to affect its safety or with itructio for use provided in the labeling can effectiveness be reasonably expected to result in a significant injury to the user National Semiconductor National Semiconductor National Semiconductor National Semiconductor Corporation Europe Hong Kong Ltd Japan Ltd 1111 West Bardin Road Fax (a49) th Floor Straight Block Tel Arlington TX cnjwge tevm2 c com Ocean Centre 5 Canton Rd Fax Tel 1(800) Deutsch Tel (a49) Tsimshatsui Kowloon Fax 1(800) English Tel (a49) Hong Kong Fran ais Tel (a49) Tel (852) Italiano Tel (a49) Fax (852) National does not assume any respoibility for use of any circuitry described no circuit patent licees are implied and National reserves the right at any time without notice to change said circuitry and specificatio