Overview
The LM4991MAX/NOPB is a mono bridged audio power amplifier designed by Texas Instruments. This amplifier is capable of delivering 3W of continuous average power into a 3Ω load with less than 10% Total Harmonic Distortion (THD) when powered by a 5V supply. It is particularly suited for low-power portable applications due to its low supply voltage range of 2.2V to 5.5V and ultra-low current shutdown mode. The LM4991 features improved click and pop circuitry, thermal shutdown protection, and unity-gain stability, making it an ideal choice for various audio systems.
Key Specifications
| Parameter | Test Conditions | Units | Typical | Limit |
|---|---|---|---|---|
| Output Power | VDD = 5V, RL = 3Ω | W | 3 | - |
| Output Power | VDD = 5V, RL = 4Ω | W | 2.5 | - |
| Output Power | VDD = 5V, RL = 8Ω | W | 1.5 | - |
| THD+N | PO = 0.5W, f = 1kHz | % | 0.2 | - |
| PSRR | VRIPPLE = 200mV sine p-p, f = 1kHz | dB | 64 | 55 (min) |
| Quiescent Power Supply Current | VIN = 0V, no Load | mA | 3 | 7 (max) |
| Shutdown Current | VSHUTDOWN = VDD | µA | 0.1 | 2.0 (max) |
| Shutdown Voltage Input High | - | V | 1.1 | - |
| Shutdown Voltage Input Low | - | V | 0.9 | - |
Key Features
- Ultra-low current shutdown mode (ISD = 0.1µA, typ)
- No output coupling capacitors, snubber networks, bootstrap capacitors, or gain-setting resistors required
- Improved click and pop circuitry reduces noises during turn-on and turn-off transitions
- Unity-gain stable
- Can drive capacitive loads up to 500pF
- Thermal shutdown protection
- External gain setting
- Operating voltage range: 2.2V to 5.5V
Applications
- Wireless and cellular handsets
- PDAs
- Portable computers
- Desktop computers
Q & A
- What is the maximum output power of the LM4991 when driving a 3Ω load from a 5V supply?
The LM4991 can deliver up to 3W of continuous average power into a 3Ω load with less than 10% THD when powered by a 5V supply. - What is the shutdown current of the LM4991?
The shutdown current of the LM4991 is typically 0.1µA when VSHUTDOWN = VDD. - What is the operating voltage range of the LM4991?
The LM4991 operates within a voltage range of 2.2V to 5.5V. - Does the LM4991 require output coupling capacitors or snubber networks?
No, the LM4991 does not require output coupling capacitors, snubber networks, bootstrap capacitors, or gain-setting resistors. - What is the typical PSRR of the LM4991 at 1kHz?
The typical Power Supply Rejection Ratio (PSRR) of the LM4991 at 1kHz is 64 dB. - What kind of thermal protection does the LM4991 have?
The LM4991 features thermal shutdown protection to prevent overheating. - Can the LM4991 drive capacitive loads?
Yes, the LM4991 can drive capacitive loads up to 500pF. - What are some common applications of the LM4991?
The LM4991 is commonly used in wireless and cellular handsets, PDAs, portable computers, and desktop computers. - How does the LM4991 reduce click and pop noises?
The LM4991 features improved click and pop circuitry to reduce noises during turn-on and turn-off transitions. - Is the LM4991 unity-gain stable?
Yes, the LM4991 is unity-gain stable.
