TS421IDT STMicroelectronics, TS421IDT Datasheet - Page 27

• Manufacturer Part Number: TS421IDT
• Description: IC AMP AUDIO .367W MONO AB 8SOIC
• Manufacturer: STMicroelectronics
• Type: Class ABr

Specifications of TS421IDT

• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 367mW x 1 @ 16 Ohm
• Voltage - Supply: 2 V ~ 5.5 V
• Features: Differential Inputs, Short-Circuit Protection, Standby
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-4066-2

APPLICATION INFORMATION
The TS419 & TS420 are monolithic power
amplifiers with a BTL output type. BTL (Bridge
Tied Load) means that each end of the load is
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)
The output power is :
For the same power supply voltage, the output
power in BTL configuration is four times higher
than
configuration.
In the flat region (no C
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
phased 180 with Vin. This means that the positive
terminal of the loudspeaker should be connected
to Vout2 and the negative to Vout1.
In the low frequency region, C
effect. C
-3dB cut off frequency .
For the second stage : Vout2 = -Vout1 (V)
BTL Configuration Principle
Gain In Typical Application Schematic
(cf. page 3 of TS419-TS421 datasheet)
Low and high frequency response
the
IN
Vout
Gv
forms with R
Pout
output
Vout
F
2
CL
Vout
Vout
1
2 (
2
2
Vin
power
IN
1
Vout
RinCin
Vin
Vout
IN
1
effect), the output voltage
R
2
a high-pass filter with a
L
Rfeed
Vin
RMS
Rin
1
IN
in
Rfeed
)
2
2
(Hz)
Rin
starts to have an
Rfeed
(
(
) V
W
Rin
single
)
(
) V
ended
In the high frequency region, you can limit the
bandwidth by adding a capacitor (Cfeed) in
parallel with Rfeed. It forms a low-pass filter with a
-3dB cut off frequency .
Hypothesis:
and Iout)
• Supply voltage is a pure DC source (Vcc)
Regarding the load we have:
and
and
Then, the average current delivered by the supply
voltage is:
The power delivered by the supply voltage is:
Psupply = Vcc Icc
Then, the power dissipated by the amplifier is:
Pdiss = Psupply - Pout (W)
and the maximum value is obtained when:
Remark : This maximum value is only dependent
upon power supply voltage and load values.
• Load voltage and current are sinusoidal (Vout
and its value is:
Power dissipation and efficiency
Pdiss
F
CH
Pdiss
V
Icc
OUT
P
2
OUT
2
I
OUT
AVG
AVG
2
max
R
Rfeed
Vcc
L
Pdiss
V
P
(W)
PEAK
OUT
V
2
1
V
PEAK
2
R
OUT
V
2
P
R
Cfeed
PEAK
L
OUT
Vcc
sin
L
R
2
R
0
2
L
(
L
) A
(
2
( t
W
(
) A
(
P
TS419-TS421
) V
W
)
OUT
(
Hz
)
)
(
W
)
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