Overview
The LMC7221AIM5/NOPB, produced by Texas Instruments, is a micropower CMOS comparator designed for space and weight-critical applications. It is available in a tiny 5-Pin SOT-23 package, which is less than 1.43 mm thick, making it ideal for saving space on printed circuit boards. This comparator operates at supply voltages of 2.7V, 5V, and 15V, ensuring performance across a wide voltage range. The LMC7221 features an open drain output, which is particularly useful in mixed voltage systems, and it has low supply current and high input impedance, making it suitable for battery-powered and high-impedance signal applications.
Key Specifications
| Parameter | Test Conditions | LMC7221AI | LMC7221BI | Units | |||
|---|---|---|---|---|---|---|---|
| VOS | Input Offset Voltage | 3 | 5 | mV | 8 | 18 | |
| TCVOS | Input Offset Voltage Temperature Drift | 1.0 | μV/°C | ||||
| IB | Input Current | 0.04 | pA | ||||
| IOS | Input Offset Current | 0.02 | pA | ||||
| CMRR | Common Mode Rejection Ratio | V+ = 5.0V | dB | 75 | |||
| AV | Voltage Gain | dB | 100 | ||||
| CMVR | Input Common-Mode Voltage Range | V+ = 5.0V | V | 5.3 | |||
| VOL | Output Voltage Low | ILOAD = 5 mA | V | 0.2 | 0.55 | ||
| IS | Supply Current | VOUT = Low | μA | 7 | 14 |
Key Features
- Tiny Package: Available in a 5-Pin SOT-23 package, which is less than 1.43 mm thick, ideal for space and weight-critical designs.
- Wide Voltage Range: Characterized at 2.7V, 5V, and 15V, making it suitable for devices where the voltage may vary.
- Open Drain Output: Useful in mixed voltage systems, similar to the open collector output of a logic gate.
- Low Supply Current: Typical supply current of 7 μA at 5V, extending battery life in portable applications.
- High Input Impedance and Low Input Currents: Allows for sensing high impedance signals from sensors and reduces power dissipation in timing circuits.
- Direct Sensor Interfacing: Can directly interface with sensors without the need for amplifiers or bias circuits, saving cost, space, and design time.
- Low Voltage Operation: Operates at supply voltages as low as 2.7V without sacrificing performance, making it suitable for 3V digital systems.
Applications
- Mixed Voltage Battery-Powered Products: Ideal for devices that operate across different voltage levels.
- Notebooks and PDAs: Suitable for portable electronic devices due to its low power consumption and small size.
- PCMCIA Type III Cards: The low height of the package makes it compatible with PCMCIA type III cards.
- Sensor Interfaces: Can directly interface with sensors, eliminating the need for additional amplifiers or bias circuits.
- Timing Circuits: Useful in timing circuits built with large value resistors to reduce power dissipation.
Q & A
- What is the typical supply current of the LMC7221 at 5V?
The typical supply current is 7 μA at 5V.
- What are the available package types for the LMC7221?
The LMC7221 is available in 5-Pin SOT-23 and 8-Pin SOIC packages.
- What is the input common-mode voltage range for the LMC7221 at 5V?
The input common-mode voltage range is from -0.3V to 5.3V at 5V supply.
- Can the LMC7221 operate at low supply voltages?
Yes, it can operate at supply voltages as low as 2.7V without sacrificing performance.
- What is the response time of the LMC7221 at 5V?
The response time is typically 4 μs at 5V.
- Is the LMC7221 suitable for mixed voltage systems?
Yes, the open drain output makes it very useful for mixed voltage systems.
- How does the LMC7221 help in reducing power dissipation in timing circuits?
It allows the use of high value resistors, which can reduce the size and cost of large value capacitors for the same R-C time constant.
- Can the LMC7221 directly interface with sensors?
Yes, it can directly interface with sensors without the need for amplifiers or bias circuits.
- What are the benefits of using multiple LMC7221 comparators instead of dual or quad comparators?
Using multiple LMC7221 comparators can simplify board layout, reduce complex signal routing, and minimize crosstalk.
- What is the maximum allowable power dissipation for the LMC7221?
The maximum allowable power dissipation is a function of TJ(MAX) and θJA, calculated as PD = (TJ(MAX) – TA)/ θJA.
