The Philips Semiconductors TDA8551 is a small audio amplifier with an
integrated volume control. When operated from +5 V, it delivers a
nominal output power of more than one watt into 8 ohms. It can also be
used over a supply voltage range of +2.7 to +5.5 V, with correspondingly
reduced output power. The output volume can be adjusted from –60 dB to
+20 dB in 64 steps, using a set of up and down push-buttons. The shared
UP/DOWN input for the up and down switches has three states. If it is
‘floating’, which means that both of the switches are open, the volume
remains unchanged. A pulse to earth decreases the volume by 1.25 dB,
while a positive pulse increases the volume by 1.25 dB.
![AF Amplifier With Digital Up Down Volume Control Based On TDA8551](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_scW5QbCyqb1JhuJr_bHO4k6wTWabx86CBocW-IXW7Q_CFVanu5RHtsJhCgf8_DGCHwfKf7cc74M5SWyGsGYPRtp4luo9nk-A5V8Qd22c69u9AJQx1wHTq2N8z9qWom13o5pst9P7tS_f6xF--W4ABKbn6bWXKq-u_FFDTM_r5i-Wcq1osWMH0Pwp0Nc4sC=s0-d)
When
the power is switched on, the internal counter takes on the –20 dB
setting. An additional input (MODE) allows the amplifier to be switched
from the operating state to the mute or standby state. If this input is
held at the earth level, the amplifier is operational. If +5 V is
applied to this pin, the TDA8551 enters the Standby mode, in which the
current consumption drops from the typical operational level of 6mA to
less than 10µA. Finally, the MODE input can be used as a mute input by
applying a voltage of 1 t0 3.6 V to this input. This voltage can be
provided by a connection to the SCR pin, which lies at half of the
operating voltage and to which a filter capacitor is connected.
![TDA8551/TDA8551T Pinout Diagram](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_sfikcmqaka9wNbujmCRH3FogZ2LCdkQcSyHMSy_m5I062QO-fiD-MMumyqMyic3M6cWwnwWTTWWyfk7g6tFi_pxMEvKK975Wi0qJYBCQd8fF7IhQ4qNBnPGOSQ5Qm9FlGIH0s=s0-d)
The
loudspeaker is connected in a floating configuration between the two
outputs of the bridge amplifier in the TDA8551. This provides the
desired output power level, in spite of the low supply voltage. For
headphone applications, which do not need as much output power, you can
connect the headphone between earth and one of the outputs, via an
electrolytic coupling capacitor. You can make a stereo headphone
amplifier in this way, using two TDS8551 ICs. The TDA8551 is housed in a
DIP8 package. The SMD version is the TDA8551T, in an SO8 package.
No comments:
Post a Comment