Datasheet MAX9700 (Maxim) - 9

MAX9700 1.2W, Low-EMI, Filterless, Class D Audio Amplifier tSW VIN- VIN+ OUT- OUT+ tON(MIN) VOUT+ - VOUT- Figure 1. MAX9700 Outputs with an Input Signal Applied
Table 1. Operating Modes External Clock Mode
The SYNC input allows the MAX9700 to be synchronized
SYNC INPUT MODE
to a system clock (allowing a fully synchronous system), GND FFM with fS = 1100kHz or allocating the spectral components of the switching UNCONNECTED FFM with fS = 1450kHz harmonics to insensitive frequency bands. Applying an VDD SSM with fS = 1220kHz ±120kHz external TTL clock of 800kHz to 2MHz to SYNC syn- Clocked FFM with fS = external clock frequency chronizes the switching frequency of the MAX9700. The period of the SYNC clock can be randomized, enabling tooth waveform changes from cycle to cycle (Figure 2). the MAX9700 to be synchronized to another MAX9700 Instead of a large amount of spectral energy present at operating in SSM mode. multiples of the switching frequency, the energy is now
Filterless Modulation/Common-Mode Idle
spread over a bandwidth that increases with frequency. The MAX9700 uses Maxim’s modulation scheme that Above a few megahertz, the wideband spectrum looks eliminates the LC filter required by traditional class like white noise for EMI purposes (Figure 3). D amplifiers, improving efficiency, reducing component count, and conserving board space and system cost. Conventional class D amplifiers output a 50% duty cycle www.maximintegrated.com Maxim Integrated │ 9