max9712eub Maxim Integrated Products, Inc., max9712eub Datasheet - Page 10

• Manufacturer Part Number: max9712eub
• Description: Max9712 500mw, Low Emi, Filterless, Class D Audio Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

Figure 2. MAX9712 Output with an Input Signal Applied (SSM Mode)
the load as a DC voltage, resulting in finite load current,
increasing power consumption. When no signal is pre-
sent at the input of the MAX9712, the outputs switch as
shown in Figure 4. Because the MAX9712 drives the
speaker differentially, the two outputs cancel each
other, resulting in no net idle mode voltage across the
speaker, minimizing power consumption.
Efficiency of a class D amplifier is attributed to the
region of operation of the output stage transistors. In a
class D amplifier, the output transistors act as current-
steering switches and consume negligible additional
power. Any power loss associated with the class D out-
put stage is mostly due to the I
on-resistance, and quiescent current overhead.
500mW, Low EMI, Filterless,
Class D Audio Amplifier
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V
V
V
OUT+
IN+
IN-
- V
OUT-
OUT+
OUT-
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ON(MIN)
R loss of the MOSFET
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Efficiency
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The theoretical best efficiency of a linear amplifier is
78%, however, that efficiency is only exhibited at peak
output powers. Under normal operating levels (typical
music reproduction levels), efficiency falls below 30%,
whereas the MAX9712 still exhibits >80% efficiencies
under the same conditions (Figure 5).
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