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STA5150 View Datasheet(PDF) - STMicroelectronics

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Description
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STA5150
ST-Microelectronics
STMicroelectronics ST-Microelectronics
STA5150 Datasheet PDF : 14 Pages
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STA5150
FUNCTIONAL DESCRIPTION
The circuit contains all the blocks to build a mono amplifier. It is based on the Output Bridge Power Amplifier,
and its protection circuit. Moreover, the compression function and a signal rectifier are added to complete the
circuit.
The operation modes are driven by The Turn-on/off sequence block. In fact the IC can be set in three states by
the Stby/mute pin:
Standby ( Vpin < 0.8V), Mute (1.6V < Vpin < 3V), and Play (Vpin > 4V).
In the Standby mode all the circuits involved in the signal path are in off condition, instead
in Mute mode the circuits are biased but the Speakers Outputs are forced to ground potential.
These voltages can be get by the external RC network connected to Stby/Mute pin.
The same block is used to force quickly the I.C. In standby mode or in mute mode when the I.C. dangerous
condition has been detected. The RC network in these cases is used to delay the Normal operation restore.
The protection of the I.C. are implemented by the Over Temperature, Unbalance Ground, Output Short circuit,
Under voltage, and output transistor Power sensing as shown in the following table:
Table 1. Protection Implementation
Fault Type
Condition
Chip Over
temperature
Tj > 130 °C
Chip Over
temperature
Tj > 150 °C
Unbalancing
Ground
|Vgnd| > ((CD+) -
(CD-))/2 + 5V
Short circuit
Iout > 14A
Protection strategy
Action time
Mute
Fast
Standby
Fast
Standby
Fast
Standby
Fast
Under Voltage
|Vs+| + |Vs-|< 20V Standby
Fast
Extra power
dissipation
at output transistor
Maximum power
dissipation
at output transistor
Pd tr. > 64W
Pd tr. > 120W
Reducing DIGITAL Related to the
CONVERTER output DIGITAL
voltage.
CONVERTER
Standby
Fast
See the POWER PROTECTION paragraph for the details
Release time
Slow Related to
Turn_on sequence
Slow, Related to
Turn_on sequence
Slow, Related to
Turn_on sequence
Slow, related to
Turn_on sequence
Slow, related to
Turn_on sequence
Related to the
DIGITAL
CONVERTER
Slow, related to
Turn_on sequence
Compression
An other important function implemented, to avoid high power dissipation and clipping distortion, is the Com-
pression of the signal input. In fact the preamplifier stage performs a voltage gain equal to 5, fixed by Ri and Rr
external resistor, but in case of high input signal or low power supply voltage, its gain could be reduced of 26dB.
This function is obtained with a feedback type compressor that , in practice, reduces the impedance of the ex-
ternal feedback network. The behavior of compression it's internally fixed but depends from the Audio input volt-
age signal level, and from the Threshold voltage applied to the Threshold pin. The attack and release time are
programmable by the external RC network connected to the Att_Rel pins.
The constraints of the circuit in the typical application are the following:
Vthreshold range
= -5 to 0
Vin peak max
= 8V
Vout peak max
= 10V
7/14
 

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