Philips AN1651 manual Intermediate Amplifier and Output Stage Figure, III. Characteristics

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Philips Semiconductors

Application note

 

 

 

Using the NE/SA5234 amplifier

AN1651

 

 

 

VCC

VIN

VCC

 

VIN

V

 

VOUT

 

 

VOUT

CC

 

 

 

 

 

5V

 

47k

 

 

 

5V

 

+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VIN

 

 

 

 

VGND

t

±

VOUT

t

VGND

 

 

47k

 

 

 

 

 

 

 

VGND

 

 

 

 

CONVENTIONAL OP AMP

 

 

PHILIPS NE5234

SL00569

Figure 2. Output Inversion Protection

(VOLTS)

6

 

 

 

 

5

 

 

 

 

VOLTAGE

 

 

 

 

4

 

ªN-MODEº

 

ªLARGE

 

 

 

MODE

3

 

CMRR

 

SIGNALº

 

VEE+1 < VCM < VCC

CMRR

COMMON

2

 

 

 

 

1

 

ªN-MODEº

 

 

 

 

0.5

 

 

VEE < VCM < VEE+0.5V

CMRR

 

 

 

 

 

-0.1

+0.1

VOS

 

VEE

 

-1

 

 

 

 

 

mV

 

 

NE5234 Common-Mode Operating Regions

SL00631

 

Figure 3.

For negative going input signals, which drive the inputs toward the VEE rail and below, another set of diode-connected transistors come into operation. These steer the current from the input into Q8 or Q9 emitter circuits again preventing the reversal effect.

Figure 3 shows graphically how the N and P mode transitions relate to the common-mode input voltage and the offset voltage VOS.

Intermediate Amplifier and Output Stage (Figure 4)

The intermediate stage is isolated from the input amplifier by emitter followers

to prevent any adverse loading effect. This stage adds gain to the over all amplifier and translates levels for the following class-AB current-control driver. Note that I2 is the inverting input and I1 the

non-inverting input. The output is taken from multiple collectors on the non-inverting side and provides matching for the following stage.

Class-AB control of the output stage is achieved by Q61 and Q62 with the associated output current regulators. These act to monitor the smallest current of the non-load supporting output transistor to keep it in conduction. Thus, neither Q71 or Q81 is allowed to cutoff but is forced to remain in the proper Class-AB region.

Overload protection is provided by monitor circuits consisting of R76-D2 for sinking and R86-D3 for sourcing condition at the output. When the output current, source or sink, reaches 15 milliamperes, drive current to the stage is shunted away from current sources IB6 or IB9 reducing base current to driver transistors Q72 and Q82 respectively.

The prevention of saturation in the output stage is achieved by saturation detectors Q78 and Q88. When either Q71 or Q81 approaches saturation, current is shunted away from the driver transistors, Q72 or Q83 respectively.

III. CHARACTERISTICS

Internal Frequency Compensation

The use of nested Miller capacitors C2 through C6, in the intermediate and output sections, provides the overall frequency compensation for the amplifier. The dominant pole setting capacitor, C2, provides a constant 6dB/octave roll-off to below the unity gain frequency of 2.5MHz. Figure 5 shows the measured frequency response plot for various values of closed-loop gains.

1991 Oct

3

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Contents AN1651 Summary II. Detailed DescriptionInput Stage III. Characteristics Intermediate Amplifier and Output Stage FigureInternal Frequency Compensation NE5234 Closed Loop Gain vs Frequency Guide Lines for Minimizing Noise IV. Noise Referred to the InputAmplified Noise = 160μVRMS VI. Multiple Stage ConsiderationsTHD vs Supply Voltage for 1VRMS Output VII. LOW Harmonic DistortionVIII. GAIN-BANDWIDTH VS Closed Loop FRE- Quency Response IX. LOOP-GAINSlew Rate Response XI. Procedures Single Supply OperationNon-Inverting Stage Biasing Strain Gauge Amplifier Applications Examples InstrumentationTo 20mA Current Loop Communications and Audio Active filtersActive Filters Fiber Optic Receiver for Low Frequency Data Figure NE578 ReferencesNE570/571/SA571 System Level Half Bridge Servo

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.
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