1. general description the hef4538b is a dual retriggerable-resettable monostable multivibrator. each multivibrator ha s 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, always connected to ground) for connecting the external timing components c ext and r ext . typical pulse width variation over the specified temperature range is ? 0.2 %. the multivibrator may be triggered by either the positive or the negative edges of the input pulse and will produce an accurate out put pulse with a pulse width range of 10 ? s to infinity. the duration and accuracy of the output pulse are determined by the external timing components c ext and r ext . the output pulse width (t w ) is equal to r ext ? c ext . the linear design techniques in locmos (l ocal oxide cmos) guar antee precise control of the output pulse width. a low level at ncd terminates the output pulse immediately. the trigger inputs? schmitt trigger action makes the circuit highly tolerant of slower rise and fall times. it operates over a recommended v dd power supply range of 3 v to 15 v referenced to v ss (usually ground). unused inputs must be connected to v dd , v ss , or another input. 2. features and benefits ? tolerant of slow trigger rise and fall times ? fully static operation ? 5 v, 10 v, and 15 v parametric ratings ? standardized symmetrical output characteristics ? specified from ? 40 ? c to +85 ? c and ? 40 ? c to +125 ? c ? complies with jedec standard jesd 13-b 3. ordering information hef4538b dual precision monostable multivibrator rev. 9 ? 10 december 2013 product data sheet table 1. ordering information all types operate from ? 40 ? c to +125 ? c. type number package name description version hef4538bp dip16 plastic dual in-line package; 16 leads (300 mil) sot38-4 hef4538bt so16 plastic small outline package ; 16 leads; body width 3.9 mm sot109-1
hef4538b all information provided in this document is subject to legal disclaimers. ? nxp b.v. 2013. all rights reserved. product data sheet rev. 9 ? 10 december 2013 2 of 18 nxp semiconductors hef4538b dual precision monost able multivibrator 4. functional diagram fig 1. functional diagram d d h $ & |