TS489 STMicroelectronics, TS489 Datasheet - Page 25

• Manufacturer Part Number: TS489
• Description: Pop-free 120mW stereo headphone amplifier
• Manufacturer: STMicroelectronics

TS488-TS489
4.5
4.6
Note:
4.7
Gain setting
In the flat frequency response region (with no effect from C
is:
The gain A
Decoupling of the circuit
Two capacitors are needed to properly bypass the TS488 (TS489), a power supply capacitor
C
C
indirectly on the power supply disturbances. With 1µF, you can expect THD+N performance
to be similar to the one shown in the datasheet. If C
increases in the higher frequencies and disturbances on the power supply rail are less
filtered. On the contrary, if C
are more filtered.
C
PSRR with grounded inputs in the lower frequencies:
■
■
The input capacitor C
lower the value of C
Standby mode
When the standby mode is activated an internal circuit of the TS488 (TS489) is charged
(see
Figure 82. Internal equivalent schematic of the TS488 (TS489) in standby mode
s
s
b
and a bias voltage bypass capacitor C
has a strong influence on the THD+N in the high frequency range (above 7kHz) and
If C
If C
has an influence on the THD+N in the low frequency range. Its value is critical on the
Figure
b
b
is lower than 1µF, the THD+N improves and the PSRR worsens.
is higher than 1µF, the benefit on the THD+N and PSRR is small.
V
82). A time required to change the internal circuit is a few microseconds.
is:
in
BYPASS
Vin1
Vin2
, the higher the PSRR.
in
also has a significant effect on the PSRR at lower frequencies. The
s
V
is higher than 1µF, the disturbances on the power supply rail
OUT
TS488/9
=
V
IN
A
⋅
V
b
.
⎛
– ⎝
=
25K
25K
R
------------- -
–
R
feed
R
------------- -
in
R
feed
in
⎞
⎠
s
=
is lower than 1µF, the THD+N
V
600K
600K
IN
⋅
in
, C
A
V
out
, C
GND
Vout1
Vout2
Application information
feed
), the output voltage
25/32