TS4956 datasheet(35/51 Pages) STMICROELECTRONICS

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TS4956

Application information

35/51

Application information

The TS4956 integrates 4 monolithic power amplifiers and has one differential input and two

single-ended inputs. The output amplifiers can be configured in 7 different modes as one SE

(single-ended) capacitively-coupled output, two phantom ground headphone outputs and

two BTL outputs.

Figure 1 on page 3 and Figure 2 on page 4 shows schemes of these

configurations and

Table 7 on page 6 describes these configurations in different modes.

This chapter gives information on how to configure the TS4956 in application.

4.1

Output configurations

4.1.1

Shutdown

When the device is in shutdown mode, all of the device’s outputs are in a high impedance

state.

4.1.2

Single-ended output configuration (modes 5 and 6)

When the device is woken-up via the I²C interface, output amplifier on output MLO is biased

to the VCC/2 voltage. In this configuration an output capacitor, Cout, on the single-ended

output is needed to block the VCC/2 voltage and couples the audio signal to the load.

VCC/2 voltage is present on this output in all modes (modes 1 to 7) to keep the output

capacitor Cout charged and to improve pop performance on this output during the switching

between any given mode to Mode 5 or 6.

When the device is in Mode 5 or 6 where the single-ended output MLO is active, all other

outputs are in a high impedance state.

4.1.3

Phantom ground output configuration (modes 3 and 4)

In a phantom ground output configuration (modes 3 and 4) the internal buffer is connected

to PHG pin and biased to the VCC/2 voltage. Output amplifiers (pins LHP and RHP) are also

biased to the VCC/2 voltage. One end of the load is connected to output amplifier and one to

the PHG buffer. Therefore, no output capacitors are needed. The advantage of the PHG

output configuration is fewer external components compared with a SE configuration.

However, note that in this configuration, the device has higher power dissipation (see

Section 4.3: Power dissipation and efficiency on page 37).

All other inactive outputs are in the high impedance state except for the MLO output, which

is biased to VCC/2 voltage.

To achieve better crosstalk results in this case, each speaker should be connected with

separate PHG wire (2 speakers connected with 4 wires) as shown in

Figure 1 on page 3

(instead of using only one common PHG wire for both speakers, i.e. 2 speakers connected

with 3 wires).

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