Overview
The LM27761DSGT from Texas Instruments is a low-noise, regulated, switched-capacitor voltage inverter. This device is designed to invert and regulate the input supply voltage, providing a very low-noise adjustable output. It operates within an input voltage range of 2.7 V to 5.5 V and can deliver an output current of up to 250 mA. The LM27761DSGT is particularly useful in applications requiring high current and low noise, such as powering data converters, operational amplifiers, and wireless communication systems.
Key Specifications
| Parameter | Value |
|---|---|
| Input Voltage Min | 2.7 V |
| Input Voltage Max | 5.5 V |
| Output Type | Adjustable |
| Adjustable Output Voltage Min | -5 V |
| Adjustable Output Voltage Max | -1.5 V |
| Output Current | 250 mA |
| Topology | Inverting |
| Operating Temperature Min | -40°C |
| Operating Temperature Max | 85°C |
| Package Type | WSON (8 pins) |
| Switching Frequency | 2 MHz (typical) |
| Quiescent Current | 370 µA (typical) |
| Shutdown Current | 7 µA (typical) |
Key Features
- Low Output Ripple: The LM27761DSGT operates at a 2-MHz switching frequency, reducing output resistance and voltage ripple.
- High Efficiency: The device achieves a charge-pump power efficiency greater than 80% with most loads.
- Low Quiescent Current: The device has a quiescent current of 370 µA and a shutdown current of 7 µA.
- Thermal Protection: Includes thermal shutdown to protect the device from overheating.
- Current Limit and Short-Circuit Protection: Protects the device against excessive input current and output shorts to ground.
- PFM Operation: Pulse-frequency modulation (PFM) or pulse-skipping operation to minimize quiescent current during light load conditions.
- Output Discharge in Shutdown: Actively pulls down the output voltage to ground when in shutdown mode.
- External Configuration: The output voltage is externally configurable with gain-setting resistors.
Applications
- Operational Amplifier Power: Suitable for powering operational amplifiers due to its low noise and high current capabilities.
- Wireless Communication Systems: Ideal for cellular-phone power-amplifier biasing and other wireless communication systems.
- Interface Power Supplies: Used in interface power supplies where low noise and high current are required.
- Handheld Instrumentation: Suitable for handheld instrumentation due to its low power consumption and high efficiency.
- Hi-Fi Headphone Amplifiers: Provides the necessary low-noise voltage for high-fidelity headphone amplifiers.
- Powering Data Converters: Ideal for powering data converters and other high-current, low-noise voltage applications.
Q & A
- What is the input voltage range of the LM27761DSGT?
The input voltage range is from 2.7 V to 5.5 V.
- What is the adjustable output voltage range of the LM27761DSGT?
The adjustable output voltage range is from -1.5 V to -5 V.
- What is the maximum output current of the LM27761DSGT?
The maximum output current is 250 mA.
- What is the switching frequency of the LM27761DSGT?
The switching frequency is 2 MHz (typical).
- What is the quiescent current of the LM27761DSGT in normal operation and shutdown?
The quiescent current is 370 µA (typical) in normal operation and 7 µA (typical) in shutdown.
- Does the LM27761DSGT have thermal protection?
Yes, it includes thermal shutdown to protect the device from overheating.
- How does the LM27761DSGT handle output shorts to ground?
The device has current limit circuitry that protects it against excessive input current and output shorts to ground).
- Can the output voltage of the LM27761DSGT be externally configured?
Yes, the output voltage is externally configurable with gain-setting resistors).
- What are some typical applications of the LM27761DSGT?
Typical applications include operational amplifier power, wireless communication systems, interface power supplies, handheld instrumentation, and powering data converters).
- How does the LM27761DSGT minimize quiescent current during light load conditions?
The device uses pulse-frequency modulation (PFM) or pulse-skipping operation to minimize quiescent current during light load conditions).
