AN2621

2/5

1

Description of the evaluation board

The DEMOTS488/9 is an evaluation board designed for the TS488/9 pop-free 120mW

stereo headphone amplifier.

modification of R11 or R12 values for channel 1, and of R21 or R22 values for channel 2.

C11 with R11 (or C21 with R21) create an input high-pass filter with a cut-off frequency of

24.1Hz.

C13 with a 16

Ω load (or C23 with a 32Ω load) create an output high-pass filter with a cut-off

frequency of 45.2Hz (22.6Hz). For information on how to change the value of the cut-off

frequency, refer to the datasheet.

The C12 and C22 component locations are left empty in order to add a low-pass filter if

required.

Caution:

When you apply the power supply through P1, do not invert the polarity because it would

destroy the amplifier at U1.

Table 1.

Gain per channel

Channel

Gain (V/V)

Channel 1

Channel 2

Table 2.

Evaluation board connectors

Connector

Description

P1

P2

Standby control connector:

–

pins 1 and 2 are shorted, TS488 operation mode, TS489 standby mode

–

pins 2 and 3 are shorted, TS488 standby mode, TS489 operation mode

The connector pins are as follows:

– 2: Standby control

–3: GND

P10

Input signal connector (GND and active input signal). The pin 1 and 2 for the input 1

and the pin 3 and 4 for the input 2

P20

Output signal connector (GND and active output signal). The pin 1 and 2 for the

output 1 and the pin 3 and 4 for the output 2

A

V

R12

R11

-----------

–

=

A

V

R22

R21

-----------

–

=

`

12

3

`

12

3