74HC4538DB,118

Overview

The Nexperia 74HC4538DB,118 is a dual retriggerable-resettable monostable multivibrator housed in an SSOP16 package (SOT338-1). It features two independent circuits, each with dedicated trigger inputs (nA for HIGH-to-LOW, nB for LOW-to-HIGH) and a direct reset input (nCD). Output pulse width is determined by external timing components REXT and CEXT using the formula TW = 0.7 × REXT × CEXT. The device operates on a supply voltage of 2.0 V to 6.0 V, with propagation delays ranging from 45 ns to 265 ns depending on voltage. It includes Schmitt-trigger inputs for noise immunity and clamp diodes for overvoltage tolerance.

Feature Summary

• Dual precision monostable multivibrators with separate reset inputs
• Triggering capability from both rising and falling edges via distinct inputs
• Schmitt-trigger action ensures tolerance to slow rise and fall times
• Inputs include clamp diodes allowing interface to voltages exceeding VCC

Applications

• Pulse generation and shaping
• Timing delay circuits
• Debouncing switches

Procurement Notes

Verify the specific ordering suffix ',118' against current Nexperia documentation to confirm the SSOP16 package type, as datasheet revisions have removed this package variant. Ensure the component meets the required temperature range specifications (-40 °C to +125 °C) for your application environment before finalizing procurement.

Selection Notes

Select this component when precise pulse width control is required with minimal variation over temperature. It is suitable for designs needing dual independent timers in a compact surface-mount package. Consider the external timing resistor and capacitor values carefully, as they directly dictate the output pulse duration and accuracy.

Part Context

The 74HC4538 belongs to the Nexperia 74HC series of high-speed CMOS logic devices. While the standard datasheet lists SO16 and TSSOP16 packages, the 'DB' suffix specifically denotes the SSOP16 package (SOT338-1), which was previously included in earlier revisions but noted as removed in later updates. This part provides dual monostable functionality within the broader HC logic family.

Replacement Considerations

Check for 74HC4538D or 74HC4538PW if the SSOP16 package is unavailable, noting that pinouts are compatible but physical dimensions differ. Verify if automotive-grade alternatives like 74HC4538D-Q100 are required for enhanced reliability standards.