TS4974_07 STMICROELECTRONICS [STMicroelectronics], TS4974_07 Datasheet - Page 21

• Manufacturer Part Number: TS4974_07
• Description: 1W differential audio power amplifier with up/down digital volume control pins
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TS4974
The volume is controlled by means of two pins, UP/DVC and DOWN/DVC. When the V
voltage is applied, it activates the increase or decrease in gain. When one of the input pins
is grounded, volume changing is activated. When both volume UP and DOWN functions are
activated at the same time, there is no effect on the volume.
The UP/DVC and DOWN/DVC inputs need to be pulled-up or pulled-down, so a pair of
external pull-up or pull-down resistors are required. When pull-up resistors are used, it is
dependent on the application which values of resistors you should choose in the range from
10k
adjusted by the value of the pull-up resistors.
When pull-down resistors are used, the values are chosen in the range from at least 430k
to 1M
the switch S1 or S2 during volume changing.
Table 2 on page 3
or decrease in volume. The volume can also be controlled by a microcontroller. In this case,
transistors can be used as switches for grounding the UP/DVC and DOWN/DVC pins.
The TS4974 integrates a debouncing system which does not take into account UP or
DOWN pulses that are shorter than the t
implemented. When a continuous voltage is applied to the UP or DOWN pin, the gain is
continuously increased or decreased after a certain time called t
each autorepeat sequence is longer (t
mode, the time t
Figure 42
t
range from the minimum gain -33 dB to the maximum gain +12 dB by 3 dB steps.
Figure 42. Example of volume change
debounce
Ω
to 1M
Ω
(a value 470k
, t
explains the meaning of the debounce, autorepeat and range times (respectively
autorepeat
Ω
. The current flowing through the switch S1 or S2 during volume changing is
range
indicates the values of the
Gain
(dB)
and t
V
Ω
is necessary to cover the whole gain range of the device.
UP
is recommended). Typically, in this case a 10
range
G=-33dB
G=3dB
). It shows how the volume increases over the whole volume
1.5 x t
autorepeat
t
debounce
autorepeat
debounce
V
t
range
U/D
x 1.5) to avoid any parasitic activation. In this
t
autorepeat
time. In addition, an autorepeat function is
voltages required to activate an increase
G=+12dB
autorepeat
Application information
µA
Time
Time
current flows through
. The first period of
IL
21/25
Ω