TS4990IST STMicroelectronics, TS4990IST Datasheet - Page 20
Manufacturer Part Number
IC AMP AUDIO PWR 1.2W MONO 8MSOP
Specifications of TS4990IST
Max Output Power X Channels @ Load
1.2W x 1 @ 8 Ohm
Voltage - Supply
2.2 V ~ 5.5 V
Depop, Differential Inputs, Standby, Thermal Protection
Package / Case
8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
For Use With
497-6383 - BOARD DEMO FOR TS4990
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Therefore, the power dissipated by each amplifier is:
and the maximum value is obtained when:
and its value is:
This maximum value is only dependent on power supply voltage and load values.
The efficiency is the ratio between the output power and the power supply:
The maximum theoretical value is reached when V
Decoupling of the circuit
Two capacitors are needed to correctly bypass the TS4990: a power supply bypass
an indirect influence on power supply disturbances. With a value for C
expect THD+N levels similar to those shown in the datasheet.
In the high frequency region, if C
on the power supply rail are less filtered.
On the other hand, if C
result of PSRR (with input grounded and in the lower frequency region).
to PSRR is substantial.
Note that C
has particular influence on the THD+N in the high frequency region (above 7 kHz) and
has an influence on THD+N at lower frequencies, but its function is critical to the final
is lower than 1 µF, THD+N increases at lower frequencies and PSRR worsens.
is higher than 1 µF, the benefit on THD+N at lower frequencies is small, but the benefit
, the higher the PSRR.
and a bias voltage bypass capacitor C
has a non-negligible effect on PSRR at lower frequencies. The lower the value
is higher than 1 µF, those disturbances on the power supply rail are
is lower than 1 µF, it increases THD+N and disturbances
------------------ - =
---- - = 78.5%
----------------- - = 0
of 1 µF, you can