Overview
The LM7705MM/NOPB, produced by Texas Instruments, is a low-noise negative bias generator designed to provide a stable, regulated negative voltage output. This device is particularly useful in applications where amplifiers need to swing to zero volts, such as in true zero amplifier outputs, portable instrumentation, and low-voltage split-power supplies. The LM7705 uses a switched capacitor voltage inverter technique to generate a fixed negative voltage of -0.23V from a single positive supply voltage, making it an efficient and cost-effective solution compared to traditional dual-supply configurations.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Regulated Output Voltage | -0.232 | -0.23 | -0.228 | V |
| Output Voltage Tolerance | 5% | |||
| Output Voltage Ripple | 4 mVPP | |||
| Supply Voltage | 3 | 5.25 | V | |
| Maximum Output Current | 26 mA | |||
| Quiescent Current | 78 | 100 | µA | |
| Shutdown Current | 20 | nA | ||
| Turnon Time | 500 | µs | ||
| Operating Temperature Range | -40 | 125 | °C | |
| Package | 8-Pin VSSOP |
Key Features
- Regulated Output Voltage: Provides a stable -0.23V output voltage with a tolerance of 5%.
- Low Noise: Features low output voltage ripple of 4 mVPP.
- High Efficiency: Achieves conversion efficiency up to 98%.
- Low Quiescent Current: Consumes less than 100 µA of quiescent current.
- Shutdown Capability: Can be disabled with a shutdown current of 20 nA.
- Compact Package: Available in an 8-pin VSSOP package.
- Wide Operating Temperature Range: Operates from -40°C to 125°C.
Applications
- True Zero Amplifier Outputs: Enables amplifiers to swing to zero volts, preventing output saturation and maintaining signal accuracy.
- Portable Instrumentation: Suitable for battery-powered devices requiring low-voltage operation.
- Low-Voltage Split-Power Supplies: Provides a negative bias voltage without the need for a dual-supply configuration.
- ADC Applications: Allows amplifiers to output a zero voltage signal, utilizing the full input range of an ADC.
Q & A
- What is the primary function of the LM7705MM/NOPB?
The LM7705MM/NOPB is a low-noise negative bias generator that provides a regulated -0.23V output voltage from a single positive supply voltage.
- What is the output voltage tolerance of the LM7705MM/NOPB?
The output voltage tolerance is 5%.
- What is the maximum output current of the LM7705MM/NOPB?
The maximum output current is 26 mA.
- What is the quiescent current of the LM7705MM/NOPB?
The quiescent current is less than 100 µA.
- How does the LM7705MM/NOPB achieve its negative output voltage?
The device uses a switched capacitor voltage inverter technique.
- What are the typical applications of the LM7705MM/NOPB?
Typical applications include true zero amplifier outputs, portable instrumentation, and low-voltage split-power supplies.
- What is the operating temperature range of the LM7705MM/NOPB?
The operating temperature range is from -40°C to 125°C.
- How can the LM7705MM/NOPB be disabled?
The device can be disabled by applying a logical high level to the SD input, switching the output to ground level.
- What is the package type of the LM7705MM/NOPB?
The device is available in an 8-pin VSSOP package.
- What is the conversion efficiency of the LM7705MM/NOPB?
The conversion efficiency can be up to 98%.
