June 12, 2001 - National Semiconductor Corporation (NYSE:NSM), expanding its popular Boomer? line of audio amplifiers, today announced five new audio products designed for demanding applications in notebook computers, PDAs, cellular phones, MP3 players, information appliances and other battery-powered devices.
"National Semiconductor's Boomer audio portfolio is rich in features that address customers' need for quality sound and their limited space in portable applications," said Kenneth Boyce, marketing director for National's audio amplifier product group. "The five amplifiers announced today require few external components, which translates into increased designer flexibility, and space and cost savings for the customer, while still delivering high-quality output power for portable systems."
National's newest audio amplifiers are the LM4900 audio power amplifier, the LM4892 audio amplifier with headphone capability, the LM4819 speaker amplifier, and the LM4809 and LM4810 headphone amplifiers with shutdown feature. All five of the audio amplifiers feature click and pop noise suppression circuitry to eliminate clicks during turn on and turn off. Additionally, each of these products is unity-gain stable, which ensures that the device will not oscillate, and a closed response can be configured using external gain-setting resistors, which allows for flexibility in design.
LM4900
The LM4900 Boomer audio amplifier is designed to provide high-quality output power from a low supply voltage while requiring a minimal amount of external components. Since the LM4900 does not require output coupling capacitors, bootstrap capacitors or snubber networks, it is optimally suited for low-power portable applications. In the LM4900, the PSRR performance has been improved by 15 dB over previous solutions. This reduces the effect of noise on power supply lines being picked up and amplified by the audio amplifier. An additional benefit is minimized noise to the earpiece speaker in cellular phones. In some applications, higher PSRR also eliminates the need for additional components to condition the power lines.
National's LM4900 has been designed to operate at low supply voltages. It operates at 2.0V to 5.0V, with specified operation at 2.6V. This device delivers 265 mW into 8 ohms at 1% THD+N. This is ideal for lower-power applications and is suitable for normal listening, speaker phone or ringer amplification. Additionally, this product offers an ultra-low shutdown current (0.1uA) to conserve battery life. The shutdown logic low operation also eliminates at least two external components, reducing overall system cost. The LM4900 audio amplifier's low-voltage operation provides improved talk time in cellular applications as battery voltage declines.
LM4892
In response to customers' needs for an integrated mono headphone driver, National developed the LM4892 with a headphone sense input pin, which is excellent for mono headphones and earbuds. With the added feature of improved Power Supply Rejection Ratio (PSRR), the LM4892 allows for less power supply noise susceptibility. The LM4892 has been designed to operate at a supply voltage all the way down to a low 2.6V and still provide adequate output power (280mW, 4 ohms, 2.6V, @ 1% THD), suitable for normal listening, speaker phone or ringer tone amplification. This allows for longer talk time in cellular phone applications as battery voltage declines. National's LM4892 also features ultra-low current shutdown (0.1uA) with a low logic level to provide battery savings with fewer components, thereby reducing overall system cost.
LM4819
The LM4819 Boomer speaker amplifier is a mono-bridged audio power amplifier that delivers excellent low-voltage operation for speakers in portable devices. This product provides high-quality speaker sound down to a very low 2V operation. The LM4819 is capable of delivering 300 mW root means square (rms) output power into an 8 ohm load at 10% THD+N from a 5V power supply, which makes it an ideal high-power speaker driver. The LM4819 offers a shutdown mode that only draws 0.7 microamps of current, which preserves battery life.
LM4809 and LM4810
National's LM4809 and LM4810 Boomer headphone amplifiers have low or high shutdown mode with less than 0.6 microamps draw in shutdown. The LM4809 has a shutdown low and the LM4810 has a shutdown high. Because they do not require bootstrap capacitors or snubber networks, the LM4809/10 save space, while offering excellent power supply ripple rejection. These dual stereo headphone drivers are capable of delivering 105 mW of continuous average power into a 16 ohm load with 0.1% THD+N from a 5V power supply.
Pricing and Availability
The LM4900 is available now in 8-pin MSOP packaging and is priced at $0.50, the LM4892 is available in micro SMD, MSOP and SOIC packaging, and is priced at $0.85, the LM4819 is available in SOP and MSOP packaging, and is priced at $0.19 and the LM4809 and LM4810 are available in 8-lead MSOP packaging, and are priced at $0.17 all in 1000-unit quantities.
More information on these products is available at http://www.national.com/pf/LM/LM4900.html, http://www.national.com/pf/LM/LM4892.html, http://www.national.com/pf/LM/LM4819.html, http://www.national.com/pf/LM/LM4809.html and http://www.national.com/pf/LM/LM4810.html. For more information on National Semiconductor's audio products, visit http://www.national.com/appinfo/audio/.
About National Semiconductor
National Semiconductor is the premier analog company driving the information age. Combining real-world analog and state-of-the-art digital technology, the company is focused on the fast growing markets for wireless handsets; information appliances; information infrastructure; and display, imaging and human interface technologies. With headquarters in Santa Clara, California, National reported sales of $2.1 billion for its last fiscal year and has about 10,000 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.
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