TS4890 ST Microelectronics, Inc., TS4890 Datasheet - Page 24

• Manufacturer Part Number: TS4890
• Description: 1W Mono Audio Amplifier With Standby Active High
• Manufacturer: ST Microelectronics, Inc.

TS4890
Fig. 105 : SO8 & MiniSO8 Demoboard Top
Solder Layer
Fig. 106 :
Solder Layer
The TS4890 is a monolithic power amplifier with a
BTL output type. BTL (Bridge Tied Load) means
that each end of the load are connected to two
single ended output amplifiers. Thus, we have :
Single ended output 1 = Vout1 = Vout (V)
Single ended output 2 = Vout2 = -Vout (V)
And Vout1 - Vout2 = 2Vout (V)
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BTL Configuration Principle
SO8 & MiniSO8 Demoboard Bottom
The output power is :
For the same power supply voltage, the output
power in BTL configuration is four times higher
than
configuration.
In flat region (no effect of Cin), the output voltage
of the first stage is :
The differential output voltage is
The differential gain named gain (Gv) for more
convenient usage is :
Remark : Vout2 is in phase with Vin and Vout1 is
180 phased with Vin. It means that the positive
terminal of the loudspeaker should be connected
to Vout2 and the negative to Vout1.
In low frequency region, the effect of Cin starts.
Cin with Rin forms a high pass filter with a -3dB cut
off frequency .
In high frequency region, you can limit the
bandwidth by adding a capacitor (Cfeed) in
parallel on Rfeed. Its form a low pass filter with a
-3dB cut off frequency .
For the second stage : Vout2 = -Vout1 (V)
Gain In Typical Application Schematic
(cf. page 1)
Low and high frequency response
the
Vout
Gv
F
CH
Pout
output
Vout
F
2
CL
Vout
2
Vout
1
2 (
2
Rfeed
2
Vin
power
1
Vout
RinCin
Vin
Vout
1
1
R
2
Rfeed
Cfeed
L
Vin
RMS
Rin
1
in
Rfeed
)
2
2
(Hz)
Rin
(
Rfeed
(
) V
W
Rin
single
(
Hz
)
(
) V
)
ended