GND

R1

R2

AVDD

TPA322x

AVDD

GAIN/SLV

TPA322x

IN2_M

IN1

IN2_P

IN1_P

IN1_M

+

-

+

-

IN2

14

TPA3220

SLASEN3 – JANUARY 2018

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Copyright © 2018, Texas Instruments Incorporated

Feature Description (continued)

In systems with single ended audio inputs the device gain will typically need to be set higher than for systems

with balanced audio input signals.

Figure 5. Single Ended Audio Input Configuration

9.3.2 Gain Setting And Master / Slave Operation

The gain of TPA3220 is set by the voltage divider connected to the GAIN/SLV control pin. Master or Slave mode

is also controlled by the same pin. An internal ADC is used to detect the 8 input states. The first four stages sets

the GAIN in Master mode in gains of 18, 24, 30, 34 dB respectively, while the next four stages sets the GAIN in

Slave mode in gains of 18, 24, 30, 34 dB respectively. The gain setting is latched when RESET goes high and

cannot be changed while RESET is high. Table 2 shows the recommended resistor values, the state and gain:

Table 2. Gain and Master / Slave

Master / Slave

Mode

Gain

R1 (to GND)

R2 (to AVDD)

Differential Input Signal Level

(each input pin)

Single Ended Input Signal

Level

Master

18 dB

5.6 kΩ

OPEN

2 VRMS

2 VRMS

Master

24 dB

20 kΩ

100 kΩ

1 VRMS

2 VRMS

Master

30 dB

39 kΩ

100 kΩ

0.5 VRMS

1 VRMS

Master

34 dB

47 kΩ

75 kΩ

0.32 VRMS

0.63 VRMS

Slave

18 dB

51 kΩ

51 kΩ

2 VRMS

2 VRMS

Slave

24 dB

75 kΩ

47 kΩ

1 VRMS

2 VRMS

Slave

30 dB

100 kΩ

39 kΩ

0.5 VRMS

1 VRMS

Slave

34 dB

100 kΩ

16 kΩ

0.32 VRMS

0.63 VRMS

Figure 6. Gain and Master / Slave Setup

For easy multi-channel system design TPA3220 has a Master / Slave feature that allows automatic

synchronization of multiple slave devices operated at the PWM switching frequency of a master device. This

benefits system noise performance by eliminating spurious crosstalk sum and difference tones due to

unsynchronized channel-to-channel switching frequencies. Furthermore the Master / Slave scheme is designed

to interleave switching of the individual channels in a multi-channel system such that the power supply current

ripple frequency is moved to a higher frequency which reduces the RMS ripple current in the power supply bulk

capacitors.