HEF4938BT,112

Multivibrators Overview

The HEF4938BT,112 is a dual retriggerable-resettable monostable multivibrator from the HEF4000 logic series. It operates within a recommended VDD power supply range of 3 V to 15 V and supports ambient temperatures from -40 °C to +125 °C. The device features two independent channels with active LOW trigger/retrigger inputs (nA), active HIGH trigger/retrigger inputs (nB), and overriding active LOW direct reset inputs (nCD). Output pulse width (tW) is determined by external timing components REXT and CEXT, following the relationship tW = REXT × CEXT. Propagation delays vary by voltage: at 5 V, tPHL ranges from 193 ns to 440 ns and tPLH from 173 ns to 460 ns; at 15 V, tPHL ranges from 52 ns to 120 ns and tPLH from 52 ns to 120 ns.

Multivibrators Feature Summary

• Dual precision monostable multivibrator design utilizing LOCMOS technology for precise output pulse width control.
• Supports triggering from both leading and trailing edges via separate nA and nB inputs.
• Features Schmitt trigger action on inputs to ensure high tolerance for slow rise and fall times.
• Includes fully static operation and standardized symmetrical output characteristics.

Multivibrators Applications

• Timing generation circuits requiring accurate pulse widths
• Debouncing switches or contacts
• Pulse stretching applications

Multivibrators Procurement Notes

Verify the specific ordering suffix '112' against official NXP documentation to confirm package type and tape-and-reel specifications. Ensure compatibility with the SO16 plastic small outline package if required. Confirm that the component meets the specified JEDEC standard JESD 13-B requirements for your application environment.

Multivibrators Selection Notes

Select this component when dual independent monostable functions are needed in a single package. Consider the HEF4938BT,112 for designs requiring operation across a wide voltage range of 3 V to 15 V. Evaluate the propagation delay characteristics relative to your system speed requirements, noting that delays decrease as supply voltage increases.

Multivibrators Part Context

The HEF4938B belongs to the HEF4000 series of CMOS logic devices manufactured by NXP Semiconductors. This series is known for its versatility in general-purpose digital applications. The HEF4938B specifically addresses timing needs with its dual-channel architecture, offering a robust solution for creating precise time delays or pulses in various electronic systems.

Multivibrators Replacement Considerations

HEF4938BP

Multivibrators FAQ

How is the output pulse width determined?

The output pulse width (tW) is determined by the values of the external timing resistor (REXT) and capacitor (CEXT) connected to the respective pins, calculated as tW = REXT × CEXT.

Can the output pulse be terminated early?

Yes, applying a LOW level to the overriding active LOW direct reset input (nCD) terminates the output pulse immediately.

What is the minimum value for the external timing capacitor?

The external timing capacitor (CEXT) must have a minimum value of 2000 pF.