74HCT4538DB,118

74HCT4538 Dual retriggerable precision monostable multivibrator Rev. 6 11 February 2021 Product data sheet 1. General description The 74HCT4538 is a dual retriggerable-resettable monostable multivibrator. Each multivibrator has two trigger/retrigger inputs (nA and nB), a direct reset input (nCD), two complementary outputs (nQ and nQ), and two pins (nREXT/CEXT and nCEXT) for connecting the external timing components C and R . Typical pulse width variation over temperature range is 0.2 %. The device EXT EXT may be triggered by either the positive or the negative edges of the input pulse. The duration and accuracy of the output pulse are determined by the external timing components C and EXT R . The output pulse width (T ) is equal to 0.7 R C . The linear design techniques EXT W EXT EXT guarantee precise control of the output pulse width. A LOW level at nCD terminates the output pulse immediately. Schmitt-trigger action in the trigger inputs makes the circuit highly tolerant to slower rise and fall times. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of V . CC 2. Features and benefits Tolerant of slow trigger rise and fall times High noise immunity Separate reset inputs Triggering from falling or rising edge Complies with JEDEC standard no. 7A Wide supply voltage range from 4.5 to 5.5 V CMOS low power dissipation TTL input levels Latch-up performance exceeds 100 mA per JESD 78 Class II Level B ESD protection: HBM JESD22-A114F exceeds 2000 V MM JESD22-A115-A exceeds 200 V Specified from -40 C to +85 C and from -40 C to +125 C 3. Ordering information Table 1. Ordering information Type number Package Temperature range Name Description Version 74HCT4538D -40 C to +125 C SO16 plastic small outline package 16 leads body width 3.9 mm SOT109-1 74HCT4538PW -40 C to +125 C TSSOP16 plastic thin shrink small outline package 16 leads SOT403-1 body width 4.4 mmNexperia 74HCT4538 Dual retriggerable precision monostable multivibrator 4. Functional diagram 2 1REXT/CEXT 1 1CEXT 1Q 6 5 1A 4 1B 1Q 7 3 1CD 14 2REXT/CEXT 15 2CEXT 2Q 10 11 2A 12 2B 2Q 9 13 2CD 001aae727 Fig. 1. Functional diagram nB nA V CC nREXT/CEXT V enable ref1 nCEXT GND nCD power-on reset V ref2 V CC enable nQ nQ mba338 GND Fig. 2. Logic diagram (one multivibrator) 74HCT4538 All information provided in this document is subject to legal disclaimers. Nexperia B.V. 2021. All rights reserved Product data sheet Rev. 6 11 February 2021 2 / 16