Overview

AN5278 is a monolithic integrated circuit of 4.8w × 1 channel OTL (18v, 8Ω) output audio power amplifier suitable for TV applications.

Features

• Few external components:

• No Boucherot cells (output C, R);

• No bootstrap capacitor;

• Built-in DC mute on input pins when powered off;

• Operating voltage range 12 V to 26 V (18 V typical).

application

•television

block diagram

Pin Description

Absolute Maximum Ratings

Note:

(1), T=25°C, except the working environment temperature and storage temperature.

(2),: When there is no input signal, V is as high as 35 V.

(3),: The power consumption of the package when T=70°C.

Recommended scope of work

Electrical characteristics at V= 18V , R=8Ω, f=1kHz, Vol.=5.0V, Tone=2.5V, T=25°C.

Design Reference Data

Note: The following characteristic values are design theoretical values and are not guaranteed.

Application circuit example

Instructions for use:

(1) An external radiator is required for use. The external heatsink should be fastened to the case.

(2) The fins of the integrated circuit can be grounded.

(3) Please prevent the output from shorting to V, the output from shorting to GND, and the load from shorting to GND. cocos islands

(4) The temperature protection circuit will work at a temperature of about 150°C. However, if the temperature decreases, the protection circuit will automatically deactivate and resume normal operation.

Technical Information

1. Characteristic graph

• HSIP009-P-0000 package power consumption

•ASO

Application Instructions

1), gain setting and frequency response

Internal resistors fix the gain at 30dB. The frequency response between pins 1 and 2 is R1 = 6.2 kΩ and C2 = 0.01 µF (other conditions: tone control voltage set to 2.5 V, volume control voltage set to 5 V).

The gain can be reduced by inserting a resistor Rf at Pin6 in series with the electrolytic capacitor. Voltage gain = 20 logarithms [10 kΩ/(Rf + 300 Ω)].

Bass boost is easily achieved by inserting an RC series connection between pin 8 (OUT) and pin 6 (NF). Example: Rb=12 kΩ, Cb=0.022μF.

2), tone characteristics

When the tone control voltage (V, at Pin3) changes from 2.5v to 5v, the high frequency gain gradually increases to a maximum of 9db. As V changes from 2.5 V to 0 V, the high frequency gain will gradually decrease to a maximum of -11 dB.

Treble cut can be further reduced by increasing the capacitor value at Pin2.

3), volume characteristics

The volume characteristic is logarithmic. When the volume control voltage (V, at Pin4) is 5v, the gain is maximum (30db); that is, there is no attenuation. As V decreases, the gain also decreases. When V is 0 V, the gain is at its minimum; that is, there is maximum attenuation, -69 dB.

4), dynamic range

The AN5278 is specifically designed to have as large an input dynamic range as possible. The input D-range is approximately 4.5 V[rms] or 12.7 V[pp] (measurement condition: V=18 V, adjust the gain downward by lowering the volume control voltage).

5), Internal AC mute pulse (during power on/off)

The startup response of the AN5278 is designed to be as smooth as possible. During power-up and power-down, the AC mute circuit is instantaneously connected. The input signal and any external noise interference are muted. The output DC level follows the rise and fall times of the RF pins.

Conditions: V=18V, C=100μF, C=10μF, C=1000μF.

6), internal DC mute pulse (when power off)

During power down, the decay response of the RF pins is exploited internally to generate an internal DC mute pulse. The output DC level drops rapidly. When the output level falls, any transient noise that occurs before the input pin is effectively cut off from the IC. The remaining charge in the large output capacitor (Pin8) is discharged into the IC internal path. In this way the output will start at almost 0 volts on the next start and reduce the occurrence of shock noise.

Conditions: V=18V, C=100μF, C=10μF, C=1000μF.

7), impact noise prevention

In order to reduce the occurrence of "shock" noise during power up, please be careful when choosing proper capacitance values for RF (Pin5) and NF (Pin6).

Recommendations: (1), NF=10μF RF=100μF to 330μF; due to the small NF capacitor, the low frequency cutoff is about 50 Hz.

(2), NF=22 microF RF= 220 microF to 330 microF; due to the large RF capacitance, the startup time is longer, about 1 second.