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4. AUDIO AMPLIFIER STAGE WITH MAX9736
4.1. General Description
The MAX9736A/B Class D amplifiers provide high-performance, thermally efficient amplifier solutions.
The MAX9736A delivers 2 x 15W into 8Ω loads, or 1 x 30W
into a 4Ω load. The MAX9736B delivers 2 x 6W into 8Ω loads or 1 x 12W into a 4Ω load. These
devices are pinfor-pin compatible, allowing a single audio design to work across a broad range of
platforms, simplifying design efforts, and reducing PCB inventory.
Both devices operate from 8V to 28V and provide a high PSRR, eliminating the need for a regulated
power supply. The MAX9736 offers up to 88% efficiency at 12V supply.
Pin-selectable modulation schemes select between filterless modulation and classic PWM
modulation. Filterless modulation allows the MAX9736 to pass CE EMI limits with 1m cables using
only a low-cost ferrite bead and capacitor on each output. Classic PWM modulation is optimized for
best audio performance when using a full LC filter.
A pin-selectable stereo/mono mode allows stereo operation into 8Ω loads or mono operation into 4Ω
loads. In mono mode, the right input op amp becomes available
as a spare device, allowing flexibility in system design.
Comprehensive click-and-pop reduction circuitry minimizes noise coming into and out of shutdown or
mute. Input op amps allow the user to create summing amplifiers,
lowpass or highpass filters, and select an optimal gain.
The MAX9736A/B are available in 32-pin TQFN packages and specified over the -40°C to +85°C
temperature
range.
The MAX9736A delivers 2 x 15W into 8Ω loads, or 1 x 30W
into a 4Ω load. The MAX9736B delivers 2 x 6W into 8Ω loads or 1 x 12W into a 4Ω load. These
devices are pinfor-pin compatible, allowing a single audio design to work across a broad range of
platforms, simplifying design efforts, and reducing PCB inventory.
Both devices operate from 8V to 28V and provide a high PSRR, eliminating the need for a regulated
power supply. The MAX9736 offers up to 88% efficiency at 12V supply.
Pin-selectable modulation schemes select between filterless modulation and classic PWM
modulation. Filterless modulation allows the MAX9736 to pass CE EMI limits with 1m cables using
only a low-cost ferrite bead and capacitor on each output. Classic PWM modulation is optimized for
best audio performance when using a full LC filter.
A pin-selectable stereo/mono mode allows stereo operation into 8Ω loads or mono operation into 4Ω
loads. In mono mode, the right input op amp becomes available
as a spare device, allowing flexibility in system design.
Comprehensive click-and-pop reduction circuitry minimizes noise coming into and out of shutdown or
mute. Input op amps allow the user to create summing amplifiers,
lowpass or highpass filters, and select an optimal gain.
The MAX9736A/B are available in 32-pin TQFN packages and specified over the -40°C to +85°C
temperature
range.
4.2. Features
Wide 8V to 28V Supply Voltage Range
♦ Spread-Spectrum Modulation Enables Low EMI Solution
♦ Passes CE EMI Limits with Low-Cost Ferrite Bead/Capacitor Filter
♦ Low BOM Cost, Pin-for-Pin Compatible Family
♦ High 67dB PSRR at 1kHz Reduces Supply Cost
♦ 88% Efficiency Eliminates Heatsink
♦ Thermal and Output Current Protection
♦ < 1μA Shutdown Mode
♦ Mute Function
♦ Space-Saving, 7mm x 7mm x 0.8mm, 32-Pin TQFN
Package
♦ Spread-Spectrum Modulation Enables Low EMI Solution
♦ Passes CE EMI Limits with Low-Cost Ferrite Bead/Capacitor Filter
♦ Low BOM Cost, Pin-for-Pin Compatible Family
♦ High 67dB PSRR at 1kHz Reduces Supply Cost
♦ 88% Efficiency Eliminates Heatsink
♦ Thermal and Output Current Protection
♦ < 1μA Shutdown Mode
♦ Mute Function
♦ Space-Saving, 7mm x 7mm x 0.8mm, 32-Pin TQFN
Package
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