PDM Input Class D Audio Power Amplifier

The MAX98358 is a digital pulse-density modulated (PDM) input Class D power amplifier that provides Class AB audio performance with Class D efficiency. This IC offers five selectable gain settings (3dB, 6dB, 9dB, 12dB, and 15dB) set by a single gain-select input (GAIN). The IC can be configured to produce a left channel, right channel, or (left/2 + right/2) output from the stereo input data.

The MAX98358 takes a stereo pulse density modulated (SPDM) input signal directly into the DAC. Data on the rising edge of PDMCLK is considered left-channel data while data on the falling PDMCLK edge is right channel. A mono sum feature is also implemented with SPDM data input by summing the data from both rising and falling clock edges.

Active emissions-limiting, edge-rate limiting, and overshoot control circuitry greatly reduce EMI. A filterless spread-spectrum modulation scheme eliminates the need for output filtering found in traditional Class D devices and reduces the component count of the solution.

The IC is available in 9-pin WLP (1.345mm x 1.435mm x 0.64mm) and 16-pin TQFN (3mm x 3mm x 0.75mm) packages and is specified over the -40°C to +85°C temperature range.

Applications

* Cellular Phones * Notebook and Netbook Computers * Portable Media Players * Tablets

* Single-Supply Operation (2.5V to 5.5V)

* 3.2W Output Power into 4Ω at 5V

* 1.8mA Quiescent Current (VDD = 3.7V)

* 92% Efficiency (RL = 8Ω, POUT = 1.5W)

* 29µVRMS Output Noise (AV = 6dB)

* Low 0.013% THD+N at 1kHz

* Supported PDMCLK Rates of 1.84MHz–4.32MHz and 5.28MHz–8.64MHz

* Supports Left, Right, or Left/2 + Right/2 Outputs

* Sophisticated Edge Rate Control Enables Filterless Class D Outputs

* 77dB PSRR at 217Hz

* Low RF Susceptibility Rejects TDMA Noise from GSM Radios

* Extensive Click-and-Pop Reduction Circuitry

* Robust Short-Circuit and Thermal Protection

* Available in Space-Saving Packages: 1.345mm x 1.435mm WLP (0.4mm Pitch), 3mm x 3mm TQFN