Description of the evaluation board

AN2622

2/5

1

Description of the evaluation board

The DEMOTS4909 evaluation board is designed for the TS4909 low power stereo

headphone amplifier with capacitor-less output.

modification of R1 or R2 values for the Left channel, and R3 or R4 values for the Right

channel

.

C1 with R1 (and C3 with R3) create an input high-pass filter with a cut-off frequency of

24.1Hz. C8 with a 16

Ω load (and C9 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 C2 and C4 component locations are empty in order to add a low-pass filter if required.

Table 1.

Gain per channel

Channel

Gain (V/V)

Left

Right

Table 2.

Evaluation board connectors

Connector

Description

P1

Connector for setting PHG or SE configuration of the TS4909:

–

the pins 1 and 2 are shorted, output stage is in SE mode

–

the pins 2 and 3 are shorted, output stage is in PHG mode

The connector pins are connected:

– 2 to SE/PHG control

– 3 to GND

P2

P3

Output signal connector. The connector pins are:

– 1&2: SE output 1 (GND and active signal)

– 3&4: PHG output 1 (PHG reference voltage output and active signal)

– 5&6: PHG output 2(active signal and PHG reference voltage output)

– 7&8: SE output 2 (active signal and GND)

P4

Standby control connector:

–

the pins 1 and 2 are shorted, the TS4909 is in operation mode

–

the pins 2 and 3 are shorted, the TS4909 is in standby mode

The connector pins are connected:

– 2 to standby control

– 3 to GND

P5

Input signal connector (GND and active input signal). Pins 1 and 2 for input 1 and pins

3 and 4 for input 2.

A

V

R2

R1

--------

–

=

A

V

R4

R3

--------

–

=

`

12

3

`

12

3

`

12

3

`

12

3