M74HC4538 Dual retriggerable monostable multivibrator Features High speed: t = 25 ns (typ.) at V = 6 V PD CC Low power dissipation standby state: SO-16 I = 4 A (max.) at T =25C CC A active state: DIP-16 I = 200 A (max.) at V =6V CC CC High noise immunity: V = V = 28 % V (min.) NIH NIL CC Symmetrical output impedance: TSSOP16 I = I = 4 mA (min.) OH OL Balanced propagation delays: t t PLH PHL Description Wide operating voltage range: V (opr) = 2 to 6 V CC The M74HC4538 is a high speed CMOS monostable 2 Wide output pulse width range: multivibrator fabricated with silicon gate C MOS t = 120 ns ~ 60 s over at V = 4.5 V technology. WOUT CC Pin and function compatible with Each multivibrator features both a negative A, and a 74 series 4538 positive B, edge 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 monostable multivibrators are retriggerable. That is, they may be triggered repeatedly while their outputs are generating a pulse and the pulse will be extended. Pulse width stability over a wide range of temperature and supply is achieved using linear CMOS techniques. The output pulse equation is simply: PW = 0.7 (R)(C) where PW is in seconds, R in Omhs and C is in Farads. All the inputs are equipped with protection circuits against static discharge and transient excess voltage. Table 1. Device summary Order code Package Packaging M74HC4538B1R DIP-16 Tube M74HC4538RM13TR SO-16 Tape and reel M74HC4538TTR TSSOP16 Tape and reel May 2008 Rev 2 1/18 www.st.com 18Pin connection and IEC logic symbols M74HC4538 1 Pin connection and IEC logic symbols Figure 1. Pin connections and IEC logic symbols V 1T1 1 16 CC 1T2 2 15 2T1 14 2T2 1CD 3 13 1A 4 2CD Inputs Inputs 12 2A 5 1B 11 6 2B Q1 Outputs Outputs 10 7 Q2 Q1 9 Q2 GND 8 Table 2. Pin description Pin number Symbol Name and function 1, 15 1T1, 2T1 External capacitor connections 2, 14 1T2, 2T2 External resistor, capacitor connections 3, 13 1CD, 2CD Direct reset inputs (active low) 4, 12 1A, 2A Trigger inputs (low to high, edge-triggered) 5, 11 1B, 2B Trigger inputs (high to low, edge-triggered) 6, 10 Q1, Q2 Pulse outputs 7, 9 Q1, Q2 Complementary pulse outputs 8 GND Ground (0 V) 16 V Positive supply voltage CC 2/18