Overview
The MC14538B, specifically the MC14538BDWG model, is a dual, retriggerable, resettable monostable multivibrator produced by onsemi. This component is designed to generate accurate output pulses with durations determined by external timing components, CX and RX. It can be triggered from either the positive or negative edge of an input pulse, making it versatile for various applications. The device operates within a voltage range of 3.0 Vdc to 18 Vdc and is capable of driving low-power TTL loads. It is also pin-for-pin compatible with other similar devices like the MC14528B and CD4528B, and it is Pb-free and RoHS compliant.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| DC Supply Voltage Range | -0.5 to +18.0 | V |
| Input or Output Voltage Range | -0.5 to VDD + 0.5 | V |
| Input or Output Current per Pin | ±10 | mA |
| Power Dissipation per Package | 500 | mW |
| Operating Temperature Range | -55 to +125 | °C |
| Pulse Width Range | 10 μs to 10 s | s |
| External Timing Resistance (RX) | Up to 1 MΩ (dependent on capacitor leakage) | kΩ |
| External Timing Capacitance (CX) | No limit (use discharge protection diode for CX > 15 μF) | F |
Key Features
- Unlimited rise and fall time allowed on the A trigger input
- Pulse width range from 10 μs to 10 s
- Latched trigger inputs
- Separate latched reset inputs
- Triggerable from positive (A input) or negative-going edge (B input)
- Capable of driving two low-power TTL loads or one low-power Schottky TTL load
- Pin-for-pin compatible with MC14528B and CD4528B
- Pb-free and RoHS compliant
- AEC-Q100 qualified and PPAP capable for automotive and other specific applications
Applications
The MC14538B is suitable for a variety of applications requiring precise timing and pulse generation. These include:
- Timing circuits in industrial control systems
- Pulse generators in medical devices
- Automotive systems requiring precise timing (with NLV prefix models)
- Communication equipment needing stable pulse widths
- General-purpose timing and sequencing in electronic circuits
Q & A
- What is the MC14538B?
The MC14538B is a dual, retriggerable, resettable monostable multivibrator.
- What is the operational voltage range of the MC14538B?
The operational voltage range is from 3.0 Vdc to 18 Vdc.
- How is the output pulse width determined?
The output pulse width is determined by the external timing components, CX and RX, using the formula T = RX * CX.
- Can the MC14538B be triggered from both positive and negative edges?
- What is the maximum external timing resistance (RX) that can be used?
The maximum usable resistance RX is a function of the leakage of the capacitor CX and other factors, but generally should not exceed 1 MΩ.
- Is the MC14538B Pb-free and RoHS compliant?
- What are the package options available for the MC14538B?
The MC14538B is available in SOIC-16 and TSSOP-16 packages.
- How does the reset function work on the MC14538B?
The reset function sets the reset latch and causes the capacitor to be fast charged to VDD, inhibiting any trigger inputs until the reset input is released.
- What precautions should be taken during power-down to avoid damaging the MC14538B?
Large capacitance values can cause issues during power-down. An external clamping diode may be necessary to limit power-down current surges.
- Is the MC14538B suitable for automotive applications?
