TS4621ML STMICROELECTRONICS [STMicroelectronics], TS4621ML Datasheet - Page 29

• Manufacturer Part Number: TS4621ML
• Description: High-performance class-G stereo headphone amplifier
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TS4621ML
4.3.6
Therefore, in most cases, R
C
Example:
In this case and for a -3 dB cut-off frequency of 20 Hz, C
value is 0.68
tolerance +/-20 %.
If the aim is to have the 20 Hz at -1 dB, the capacitor has to be multiplied by 1.96. As such,
C
Low-pass output filter (R
protection
The TS4621ML is designed to operate with a passive first-order low-pass filter (as shown in
Figure
over the volume range and output capacitance range vs. load.
R
maximum. Values of 12 Ω and 1 nF are a good starting point for a design to be able to drive
a classic headphone (16 Ω, 32 Ω, 60 Ω) and the line-in of any hi-fi system or sound card.
The cutoff frequency of this filter (12 Ω and 1 nF) is approximately 13 MHz and clearly
above the audio band.
However, this output RC filter is also a part of the IEC 61000-4-2 ESD protection. In most
cases, this RC filter is designed with transient absorbers and the final solution can be a
discrete solution or an integrated solution. ST Microelectronics’ portfolio has many
integrated solutions for ESD, but one dedicated to headphone amplifiers in particular:
IPAD
To fit the IEC 61000-4-2 standard, this audio line IPAD can be added to the output of the
TS4621ML as shown in
a. Copyright STMicroelectronics.
in
in
out
.
= 0.64 x 1.96 = 1.25
must have a value of 12 Ω minimum and C
(a)
1). This low-pass filter is mandatory to ensure correct operation of the TS4621ML
reference EMIF02-AV01F3.
µ
F but a 1
µ
Figure
µ
F capacitor is more suitable to take into consideration the capacitor
F. The closest normalized value would be 1.5
in
should be set to 6 dB to calculate the minimum input capacitor
Doc ID 023181 Rev 1
67.
out
and C
out
) and IEC 61000-4-2 ESD
out
a value of 0.8 nF minimum up to 100 nF
in
= 0.64
µ
F. The closest normalized
Application information
µ
F or 2.2
µ
F.
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