TS487 STMICROELECTRONICS [STMicroelectronics], TS487 Datasheet - Page 27

• Manufacturer Part Number: TS487
• Description: 100mW STEREO HEADPHONE AMPLIFIER WITH STANDBY MODE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

APPLICATION NOTE:
TS486/487 GENERAL DESCRIPTION
TS486/487 is a family of dual audio amplifiers able
to drive 16 or 32 headsets. Working in the 2V to
5.5V supply voltage range, they deliver 100mW at
5V and 12mW at 2V in a 16 load. An internal
output current limitation, offers protection against
short-circuits at the output over a limited time
period.
Fixed gain versions of the TS486 and TS487
including the feedback resistor and the input
resistors are also proposed to reduce the number
of external parts.
The TS486 and TS487 exhibit a low quiescent
current of typically 1.8mA, allowing usage in
portable applications.
The standby mode is selected using the
SHUTDOWN input. For TS486 (respectively
TS487), the device is in sleep mode when PIN 5 is
connected at GND (resp. V
GAIN SETTING
The gain of each inverter amplifier of the TS486
and TS487 is set by the resistors R
Gain
LINEAR
= -(R
FEED
/R
IN
)
CC
).
IN
and R
FEED
.
Gain
Fixed gain versions TS486-n and TS487-n
including R
external parts.
LOW FREQUENCY ROLL-OFF WITH INPUT
CAPACITORS
The low roll-off frequency of the headphone
amplifiers depends on the input capacitors C
and C
The C
R
high pass filter.
Assuming that F
amplified (with a 3dB attenuation), the minimum
value of C
C
The following curve gives directly the low
frequency roll-off versus the input capacitor C
IN
IN
> 1 / (2* *F
of the amplifier is equivalent to a first order
dB
IN2
IN
= 20 Log(R
capacitor in series with the input resistor
and the input resistors R
IN
IN
is:
and R
min
min
FEED
*R
FEED
is the lowest frequency to be
IN
/R
)
are proposed to reduce
IN
)
TS486-TS487
IN1
and R
IN2
27/31
IN1
.
IN