Philips Semiconductors

Application note

 

 

 

Using the NE/SA5234 amplifier

AN1651

 

 

 

 

 

20kΩ

 

 

 

 

 

+

 

 

 

 

 

 

A2

 

 

+4.5VDC

 

 

 

 

 

 

 

 

 

±

 

 

 

 

 

10kΩ

 

4

10Ω

 

 

 

IC-1

 

 

 

0.1μF

 

 

NE5234

 

 

 

 

 

VR1

 

 

0.1μF

 

10Ω

 

 

 

 

 

 

VCC

 

 

 

BDX45

 

 

 

 

 

 

+

 

+

+

150

 

150

 

 

 

 

 

 

 

 

 

A1

A3

 

 

 

A4

 

 

 

 

 

 

 

 

 

 

±

 

 

±

 

 

 

 

±

 

 

 

 

 

 

 

 

 

 

 

 

 

IC-2

 

 

 

 

100kΩ

 

NE5234

 

 

 

 

 

 

 

 

 

 

VR2

+

150

 

150

+

VR2

 

 

 

 

 

 

 

 

 

 

10kΩ

A5

 

 

 

A6

 

 

 

 

 

 

 

RS

±

 

 

 

±

 

CL

 

 

BDX42

 

 

 

 

 

 

 

VREF

 

 

 

 

 

PM

CS

 

 

 

 

 

 

 

 

 

 

 

MOTOR

 

 

 

 

 

 

100

 

 

 

 

 

 

1

VR1-3 = 1.4V

 

 

 

 

 

 

 

 

 

 

 

 

SL00648

Figure 20. Full Bridge Motor Drive

Active filters

The NE5234 is easily adapted to use in a variety of active filter applications. Its high open-loop gain and excellent unity gain stability make it ideal for high-pass,

band-pass and low-pass configurations operated with low voltage single supplies. Its low output impedance also makes it capable of obtaining low noise operation without resorting to separate high current buffers.

Figure 21a shows the circuit for a VCVS low-pass filter with dual supply biasing and 600Ω output termination. Figure 21b is a band-pass filter with AC coupled gain network for single supply operation.

Communications and Audio

Stereo Bridge Amplifier

Figure 22 shows two NE5234 ICs in a bridge amplifier application. The choice of split supplies allows DC coupling, both from the input signal source and to the load. The gain is set to a nominal 20dB.

Either inverting or non-inverting operation is available. The inverting input impedance is chosen as 600Ω in order to match standard

audio impedance lines within a system. The use of two such amplifiers will provide stereo operation to +10dBm for a 600Ω load.

Voice Operated Microphone

The processing of voice transmissions for communications channels is generally coupled with the need for keeping the signal-to-noise ratio high and the intelligibility optimized for a given channel bandwidth. In addition, when a circuit is battery operated and portable, the requirement to obtain maximum battery life becomes important. The circuit example shown here is aimed at filling the need for a portable voice operated transmitter, cordless phone, or tape recorder. It utilizes the Philips Semiconductors NE5234 quad op amp in conjunction with the new low-voltage NE578 compandor to create an audio processor capable of operating in just such an environment. Both devices are operational to a low battery voltage of 2.0V. In addition the design further conserves current by automatically shifting the NE578 compandor to standby during the period when no transmissions are being made. Total current consumption at 3.0V is 2.8mA for the NE5234. In the active mode the NE578 draws 1.4mA and this drops to 170μA in the standby mode. This amounts to reducing the supply current demand by approximately 25% in the `listen mode'.

1991 Oct

12

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Philips AN1651 manual Active filters, Communications and Audio

AN1651 specifications

The Philips AN1651 is a highly regarded car audio speaker offering an impressive balance of sound quality and performance. Designed primarily for the car audio enthusiast, this model showcases what modern engineering can achieve in automotive sound systems.

One of the main features of the AN1651 is its dual cone structure that produces clear and rich sound across various frequencies. This design aims to enhance both low and mid-range sounds, ensuring that music is delivered with clarity and precision. Whether you're listening to rock, pop, or classical, the AN1651 is built to convey the nuances of music effectively.

The speaker boasts a peak power handling capability of up to 240 watts, which allows for immersive sound experiences without distortion, even at higher volumes. This capability means that the AN1651 can handle the punchy bass lines typical in many contemporary music genres, making it a popular choice among bass enthusiasts.

Philips also incorporates their innovative technologies, such as a reinforced polypropylene cone. This material enhances sound quality by providing better rigidity while remaining lightweight. The result is a responsive speaker with reduced resonance, contributing to more accurate audio playback. Furthermore, the butyl rubber surround is designed to withstand wear and tear, ensuring durability and longevity in automotive conditions.

The AN1651 also features a sensitivity rating of 91 dB, allowing it to produce powerful sound output even with moderate power input. This feature makes it an ideal choice for vehicles with smaller amplifiers or factory stereo units, as it ensures an enjoyable listening experience without requiring significant upgrades.

In terms of installation, the AN1651 is designed for versatility. Its size makes it compatible with a wide range of vehicles, and the mounting accessories included facilitate an easy and secure fit.

With a smart aesthetic that blends well with various car interiors, the Philips AN1651 speaker is more than just a functional audio component; it is a stylish addition to your vehicle.

In conclusion, the Philips AN1651 combines advanced technologies and thoughtful design to deliver a rich audio experience that car enthusiasts will appreciate. Whether for casual listening or serious audio enjoyment, this speaker meets diverse audio needs, proving to be a valuable investment for any car audio system.