TPA2032D1 Datasheet, PDF (10/17 Pages) Texas Instruments – 2.75-W FIXED GAIN MONO FILTER-FREE CLASS-D AUDIO POWER AMPLIFIER

TPA2032D1
TPA2033D1
TPA2034D1
SLOS476 – JUNE 2006
APPLICATION INFORMATION
www.ti.com
FULLY DIFFERENTIAL AMPLIFIER
The TPA2032D1 is a fully differential amplifier with differential inputs and outputs. The fully differential amplifier
consists of a differential amplifier and a common-mode amplifier. The differential amplifier ensures that the
amplifier outputs a differential voltage on the output that is equal to the differential input times the gain. The
common-mode feedback ensures that the common-mode voltage at the output is biased around V_DD/2
regardless of the common-mode voltage at the input. The fully differential TPA2032D1 can still be used with a
single-ended input; however, the TPA2032D1 should be used with differential inputs when in a noisy
environment, like a wireless handset, to ensure maximum noise rejection.
Advantages of Fully Differential Amplifiers
• Input-coupling capacitors not required:
– The fully differential amplifier allows the inputs to be biased at voltage other than mid-supply. The inputs of
the TPA2032D1 can be biased anywhere within the common mode input voltage range listed in the
Recommended Operating Conditions table. If the inputs are biased outside of that range, input-coupling
capacitors are required.
• Midsupply bypass capacitor, C_(BYPASS), not required:
– The fully differential amplifier does not require a bypass capacitor. Any shift in the midsupply affects both
positive and negative channels equally and cancels at the differential output.
• Better RF-immunity:
– GSM handsets save power by turning on and shutting off the RF transmitter at a rate of 217 Hz. The
transmitted signal is picked-up on input and output traces. The fully differential amplifier cancels the signal
better than the typical audio amplifier.
COMPONENT SELECTION
Figure 35 shows the TPA2032D1 typical schematic with differential inputs, while Figure 36 shows the
TPA2032D1 with differential inputs and input capacitors. Figure 37 shows the TPA2032D1 with a single-ended
input.
Decoupling Capacitor (C_S)
The TPA2032D1 is a high-performance class-D audio amplifier that requires adequate power supply decoupling
to ensure the efficiency is high and total harmonic distortion (THD) is low. For higher frequency transients,
spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic capacitor, typically
1µF, placed as close as possible to the device V_DD lead works best. Placing this decoupling capacitor close to
the TPA2032D1 is very important for the efficiency of the class-D amplifier, because any resistance or
inductance in the trace between the device and the capacitor can cause a loss in efficiency. For filtering
lower-frequency noise signals, a 10 µF or greater capacitor placed near the audio power amplifier would also
help, but it is not required in most applications because of the high PSRR of this device. Typically, the smaller
the capacitor's case size, the lower the inductance and the closer it can be placed to the TPA2032D1.
Input Capacitors (C_I)
The TPA2032D1 does not require input coupling capacitors if the design uses a differential source that is biased
within the common-mode input voltage range. That voltage range is listed in the Recommended Operating
Conditions table. If the input signal is not biased within the recommended common-mode input range, such as in
needing to use the input as a high pass filter, shown in Figure 36, or if using a single-ended source, shown in
Figure 37, input coupling capacitors are required. The same value capacitors should be used on both IN+ and
IN– for best pop performance.
fc
+
ǒ_2p
1
RICI^Ǔ
(1)
The value of the input capacitor is important to consider as it directly affects the bass (low frequency)
performance of the circuit. Speaker response may also be taken into consideration when setting the corner
frequency using input capacitors.
10
Submit Documentation Feedback