AN3001

Configuring the demonstration board

Doc ID 15911 Rev 1

7/12

3.4

Optional measurement loads

As shown in Figure 2 on page 4, there are two resistors (R6 and R8) that are not connected

on the demonstration board. These resistors are used to measure the performances of the

TS4657 with different loads. After the test, it is best to remove them and load the TS4657

with the application only.

The load on both outputs should be higher or equal to 5 k. Generally, the standard load for

the audio line is 10 k (10 K/1 %, 0.063 W, SMD resistors, 0603).

3.5

Specific considerations

The TS4657 utilizes a power management unit to supply its internal structures.

A self-generated negative supply allows the drivers to be powered from positive and

negative supplies, thus increasing the output signal amplitude. This internal negative supply

switches at a higher frequency than traditional architectures, derived from the master clock

MCLK. This structure uses an original design that allows suppressing the flying or floating

capacitors. Therefore, only four small 1 µF decoupling capacitors are necessary for

VCCA/VCCD and VREGA/VREGD.

Furthermore, the self-generated negative supply allows the amplifier outputs to be centered

around zero, thus the bulky output coupling capacitors can be removed.

As mentioned previously, the MCLK is used internally to supply some blocks. It is therefore

not recommended to switch off the MCLK during normal operation.

To properly power-down the device, MCLK, BCLK and LRCLK should be switched off after

the STDBY signal.

The power-down time is very short and can be considered as zero.