Overview
The MC14538B, specifically the MC14538BDWR2G, 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. It can be triggered from either the positive or negative edge of an input pulse, making it versatile for various timing applications. The MC14538B is pin-for-pin compatible with other similar devices like the MC14528B and CD4528B, and it is available in several package options, including SOIC-16 and TSSOP-16, all of which are 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 (DC or Transient) per Pin | ±10 mA | mA |
| Power Dissipation, per Package | 500 mW | mW |
| Operating Temperature Range | -55 to +125 | °C |
| Pulse Width Range | 10 μs to 10 s | s |
| External Timing Resistance (RX) | Up to 5.0 MΩ (dependent on capacitor leakage and board layout) | Ω |
| External Timing Capacitance (CX) | No limit (use discharge protection diode for CX > 15 μF) | F |
| Output Rise Time (tTLH) | 100 ns to 200 ns (dependent on VDD and CL) | ns |
| Output Fall Time (tTHL) | 100 ns to 200 ns (dependent on VDD and CL) | ns |
| Propagation Delay Time (tPLH, tPHL) | 255 ns to 132 ns (dependent on VDD and CL) | ns |
Key Features
- Triggerable from either positive (A input) or negative-going edge (B input)
- Unlimited rise and fall time allowed on the A trigger input
- Latched trigger inputs and separate latched reset inputs
- Capable of driving two low-power TTL loads or one low-power Schottky TTL load
- Pin-for-pin compatible with MC14528B and CD4528B
- AEC-Q100 qualified and PPAP capable for automotive and other applications requiring unique site and control change requirements
- Pb-free and RoHS compliant
Applications
The MC14538B is suitable for a wide range of applications that require precise timing and pulse generation. These include:
- Timing circuits in industrial control systems
- Pulse width modulation in power supplies and motor control
- Automotive systems requiring AEC-Q100 compliance
- Medical devices needing precise timing signals
- Communication systems requiring stable pulse generation
Q & A
- What is the MC14538B?
The MC14538B is a dual, retriggerable, resettable monostable multivibrator.
- How can the MC14538B be triggered?
The MC14538B can be triggered from either the positive or negative edge of an input pulse.
- What determines the output pulse width of the MC14538B?
The output pulse width is determined by the external timing components, RX and CX.
- What is the operational voltage range of the MC14538B?
The operational voltage range is from 3.0 Vdc to 18 Vdc.
- Is the MC14538B compatible with other devices?
Yes, it is pin-for-pin compatible with the MC14528B and CD4528B.
- What are the packaging options for the MC14538BDWR2G?
The MC14538BDWR2G is available in SOIC-16 WB (Pb-free) packaging.
- Is the MC14538B suitable for automotive applications?
Yes, it is AEC-Q100 qualified and PPAP capable, making it suitable for automotive and other applications requiring unique site and control change requirements.
- 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?
Ensure the VDD supply discharges slowly enough to avoid surging currents through the protection diodes, and consider using an external clamping diode if necessary.
- What is the maximum usable resistance for RX?
The maximum usable resistance for RX is a function of the leakage of the capacitor CX, the MC14538B, and board layout, but generally should not exceed 5.0 MΩ.
