TS4962M ST Microelectronics, Inc., TS4962M Datasheet - Page 25

• Manufacturer Part Number: TS4962M
• Manufacturer: ST Microelectronics, Inc.

TS4962M
5.10
We have following equations:
In general, for mixed situations (single-ended and differential inputs) we must use the same
rule: equalize impedance on both TS4962M inputs.
Output filter considerations
The TS4962M is designed to operate without an output filter. However, due to very sharp
transients on TS4962M output, EMI radiated emissions may cause some standard compliance
issues.
These EMI standard compliance issues can appear if the distance between the TS4962M
outputs and loudspeaker terminal are long (typically more than 50mm, or 100mm in both
directions, to the speaker terminals). As each PCB layout and internal equipment device are
different for each configuration, it is difficult to provide a one-size-fits-all solution.
However, to decrease the probability of EMI issues, there are several simple rules to follow:
●
●
●
●
In the case where distance between TS4962M's output and speaker terminals is high, it's
possible to have low frequency EMI issues due to the fact that the typical operating frequency is
250kHz.
In this configuration, utilization of the output filter represented in page 3 and close of the
TS4962M is necessary.
Reduce, as much as possible, the distance between the TS4962M output pins and the
speaker terminals.
Uses ground plane for “shielding” sensitive wire.
Place, as close as possible to the TS4962M and in series with each output, a ferrite bead
with a rated current at minimum 2A and impedance greater than 50Ω at frequencies
>30MHz. If, after testing, these ferrite beads are not necessary, replace them by a short-
circuit. Murata BLM18EG221SN1 or BLM18EG121SN1 are possible examples.
Allow a footprint to place, if necessary, a capacitor to short perturbations to ground (see
following schematic).
From TS4962 output
Out
+
–
Out
C eq
R
C
inj
eq
-
=
=
=
=
V e1
j 1
--------------------------------------------------- -
2
------------------ -
Σ
∑
j 1
=
Ferrite chip bead
k
k
=
×
×
π
1
--------- -
C inj
R
------------ -
R in1
1
×
300
inj
R
1
inj
+
×
…
F
Gnd
+
CLj
V ek
about 100pF
×
To speaker
(F)
------------ -
R ink
300
Application Information
(V)
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