74HC4538 74HCT4538 Dual retriggerable precision monostable multivibrator Rev. 03 8 June 2009 Product data sheet 1. General description The 74HC4538 74HCT4538 are high-speed Si-gate CMOS devices and are pin compatible with Low-power Schottky TTL (LSTTL). They are specied in compliance with JEDEC standard no. 7A. The 74HC4538 74HCT4538 are dual retriggerable-resettable monostable multivibrators. Each multivibrator has an active LOW trigger/retrigger input (nA), an active HIGH trigger/retrigger input (nB), an overriding active LOW direct reset input (nCD), an output (nQ) and its complement (nQ), and two pins (nREXT/CEXT and nCEXT) for connecting the external timing components C and R . Typical pulse width variation over the EXT EXT specied temperature range is 0.2 %. The multivibrator 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 R . The output pulse width (t ) is equal to EXT EXT W 0.7 R C . The linear design techniques guarantee precise control of the output EXT EXT pulse width. A LOW level at nCD terminates the output pulse immediately. Schmitt trigger action on pins nA and nB makes the circuit highly tolerant of slower rise and fall times. 2. Features n Tolerant of slow trigger rise and fall times n Separate reset inputs n Triggering from falling or rising edge n Multiple package options n ESD protection: u HBM JESD22-A114E exceeds 2000 V u MM JESD22-A115-A exceeds 200 V n Specied from - 40 Cto+85 C and from - 40 C to +125 C74HC4538 74HCT4538 NXP Semiconductors Dual retriggerable precision monostable multivibrator 3. Ordering information Table 1. Ordering information Type number Package Temperature range Name Description Version 74HC4538N - 40 C to +125 C DIP16 plastic dual in-line package 16-leads (300 mil) SOT38-4 74HCT4538N 74HC4538D - 40 C to +125 C SO16 plastic small outline package 16 leads body width 3.9 mm SOT109-1 74HCT4538D 74HC4538DB - 40 C to +125 C SSOP16 plastic shrink small outline package 16 leads SOT338-1 body width 5.3 mm 74HCT4538DB 74HC4538PW - 40 C to +125 C TSSOP16 plastic thin shrink small outline package 16 leads SOT403-1 body width 4.4 mm 74HCT4538PW 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 74HC HCT4538 3 NXP B.V. 2009. All rights reserved. Product data sheet Rev. 03 8 June 2009 2 of 24