Overview
The CD74HC125M, produced by Texas Instruments, is a high-speed CMOS logic quad buffer with three-state outputs. This device contains four independent buffers, each performing the Boolean function Y = A in positive logic. It is designed to operate over a wide voltage range of 2 V to 6 V and a temperature range of –55°C to +125°C, making it versatile for various applications.
The CD74HC125M is available in a 14-pin SOIC package, offering a compact solution for digital signal buffering and enabling. Its low power consumption and significant power reduction compared to LSTTL logic ICs make it an efficient choice for modern electronic designs.
Key Specifications
| Parameter | Test Conditions | Unit | Min | Max | |
|---|---|---|---|---|---|
| Operating Voltage Range | V | 2 | 6 | ||
| Operating Temperature Range | °C | –55 | +125 | ||
| High-Level Output Voltage (VOH) | IOH = –20 µA, VCC = 2 V | V | 1.9 | 1.9 | 1.9 |
| High-Level Output Voltage (VOH) | IOH = –20 µA, VCC = 4.5 V | V | 4.4 | 4.4 | 4.4 |
| High-Level Output Voltage (VOH) | IOH = –20 µA, VCC = 6 V | V | 5.9 | 5.9 | 5.9 |
| Low-Level Output Voltage (VOL) | IOL = 20 µA, VCC = 2 V | V | 0.1 | 0.1 | 0.1 |
| Low-Level Output Voltage (VOL) | IOL = 20 µA, VCC = 4.5 V | V | 0.1 | 0.1 | 0.1 |
| Low-Level Output Voltage (VOL) | IOL = 20 µA, VCC = 6 V | V | 0.1 | 0.1 | 0.1 |
| Input Leakage Current (II) | VI = VCC or 0, VCC = 6 V | µA | ±0.1 | ±1 | |
| Supply Current (ICC) | VI = VCC or 0, IO = 0, VCC = 6 V | µA | 8 | 160 | |
| Three-State Leakage Current (IOZ) | VI = VIH or VIL, VCC = 6 V | µA | ±0.5 | ±10 | |
| Input Capacitance (Ci) | VCC = 5 V | pF | 10 | 10 | |
| Three-State Output Capacitance (Co) | pF | 20 | 20 |
Key Features
- Buffered Inputs: Ensures stable input signals.
- Wide Operating Voltage Range: Operates from 2 V to 6 V.
- Wide Operating Temperature Range: Functional from –55°C to +125°C.
- Three-State Outputs: Each buffer has a three-state output, allowing for high-impedance state.
- High Fanout Capability: Supports fanout up to 10 LSTTL loads.
- Low Power Consumption: Significant power reduction compared to LSTTL logic ICs.
- Balanced CMOS Outputs: Outputs can sink and source similar currents, ensuring balanced operation.
- Clamp Diode Structure: Inputs and outputs have both positive and negative clamping diodes for protection.
Applications
The CD74HC125M is suitable for a variety of digital logic applications, including:
- Digital Signal Buffering: Ideal for buffering digital signals to ensure signal integrity over long distances or through multiple stages.
- Enable Digital Signals: Can be used to enable or disable digital signals based on the output enable inputs.
- General Logic Circuits: Useful in various digital logic circuits where signal buffering and enabling are required.
Q & A
- What is the operating voltage range of the CD74HC125M?
The CD74HC125M operates from 2 V to 6 V.
- What is the temperature range for the CD74HC125M?
The device is functional from –55°C to +125°C.
- How many buffers does the CD74HC125M contain?
The device contains four independent buffers.
- What is the fanout capability of the CD74HC125M?
The device supports fanout up to 10 LSTTL loads.
- What type of outputs does the CD74HC125M have?
The device has three-state outputs.
- How should unused inputs be handled?
Unused inputs must be terminated to either VCC or ground, either directly or with pull-up/pull-down resistors.
- What is the significance of the clamp diode structure in the CD74HC125M?
The inputs and outputs have both positive and negative clamping diodes to protect against voltage spikes.
- What are the key considerations for output connections?
Outputs should not be connected directly to VCC or ground. The resistive load at the output should be larger than (VCC / IO(max)) Ω to avoid over-current damage.
- How can thermal issues be managed for the CD74HC125M?
Thermal issues are rarely a concern, but power consumption and thermal increase can be calculated using the CMOS Power Consumption and Cpd Calculation application report.
- What is the recommended layout practice for the CD74HC125M?
A decoupling capacitor should be placed close to the device, and short, appropriately sized traces should be used to minimize capacitive loads.
