74HC4538N,652

Overview

The 74HC4538N,652 is a dual retriggerable-resettable monostable multivibrator manufactured by Nexperia. It operates within a supply voltage range of 2.0 V to 6.0 V and supports an ambient temperature range from -40 °C to +125 °C. The device features two trigger inputs (nA and nB) per multivibrator, allowing triggering from either positive or negative edges. Pulse width is determined by external components REXT and CEXT using the equation TW = 0.7 × REXT × CEXT. Propagation delay ranges from 45 ns to 265 ns depending on voltage. Output current capability is ±5.2 mA.

Feature Summary

• Dual precision monostable multivibrator with retriggerable functionality
• Schmitt-trigger action on inputs for tolerance to slow rise and fall times
• Direct reset input (nCD) to terminate output pulse immediately
• CMOS low power dissipation with high noise immunity

Applications

• Pulse generation and timing circuits
• Debouncing switches
• Frequency division
• Timer applications requiring precise pulse width control

Procurement Notes

Verify the package type matches the required PCB footprint, as the 74HC4538 family includes SO16 and TSSOP16 variants. Confirm the ordering suffix corresponds to the specific manufacturer's packaging and tape-and-reel specifications. Ensure the component meets the required operating temperature range for the intended application environment.

Selection Notes

Select this component when dual independent monostable circuits are needed in a single package. Consider the wide supply voltage range suitable for various logic families. Evaluate the external timing components' stability requirements, as pulse width accuracy depends on REXT and CEXT values. Check propagation delay specifications against system timing constraints.

Part Context

The 74HC4538 belongs to the 74HC series of high-speed CMOS logic devices. It is functionally compatible with other monostable multivibrators like the CD4528 and CD4538. The device utilizes advanced silicon-gate CMOS technology, offering performance comparable to low-power Schottky TTL while maintaining CMOS advantages.

Replacement Considerations

Check pin compatibility with existing designs if substituting with other monostable multivibrators. Verify that alternative packages (e.g., TSSOP vs. SOIC) fit the mechanical constraints. Ensure electrical characteristics such as propagation delay and output drive current meet the original design requirements.