Maxim claims Class D amps will simplify audio design
The MAX98355A/MAX98355B are digital pulse-code modulation (PCM) input Class D power amplifiers that provide Class AB audio performance with Class D efficiency. These ICs offer five selectable gain settings (3dB, 6dB, 9dB, 12dB, and 15dB) set by a single gain-select input (GAIN).
The digital audio interface is highly flexible with the MAX98355A supporting I²S data and the MAX98355B supporting left-justified data. Both ICs support time division multiplexed (TDM) data. The digital audio interface accepts sample rates ranging from 8kHz to 96kHz for all supported data formats. The ICs can be configured to produce a left channel, right channel, or (left + right)/2 output from the stereo input data. The ICs operate using 16/24/32-bit data for I²S and left justified modes as well as 16-bit data with up to four slots when using TDM mode. The ICs eliminate the need for the external MCLK signal that is typically used for PCM communication. This reduces EMI and possible board coupling issues in addition to reducing the size and pin count of the ICs.
The ICs also feature a very high wideband jitter tolerance (12ns typ) on BCLK and LRCLK to provide robust operation.
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.
- Single-Supply Operation (2.5V to 5.5V)
- 3.2W Output Power into 4Ω at 5V
- 2.2mA Quiescent Current
- 92% Efficiency (RL = 8Ω, POUT = 900mW, VDD = 3.7V)
- 25µVRMS Output Noise (AV = 15dB)
- Low 0.013% THD+N at 1kHz
- No MCLK Required
- Sample Rates of 8kHz to 96kHz
- Supports Left, Right, or (Left + 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 Package: 1.345mm x 1.435mm WLP (0.4mm Pitch)
Maxim Integrated has introduced a couple of digital-input Class D power amplifiers that it claims will simplify audio designs by eliminating complicated programming.
“Audio design can be simplified because internal circuitry in the MAX98355/MAX98356 detects the input clock and automatically calculates the sample rate.
According to the supplier, this reduces complicated programming and the need for system software support.
“These digital-input Class D amplifiers make system design nearly plug and play,” said Robert Nicoletti, applications manager at Maxim Integrated.
The MAX98355 (pulse-code modulation, PCM) and MAX98356 (pulse-density modulation, PDM) offer high jitter tolerance with low 0.013% THD+N at 1kHz and 99dB dynamic range.
Power efficiency is 92% at RL = 8?, POUT = 900mW, VDD = 3.7V.
The chips are available in a 9-pin WLP package (1.345mm x 1.435mm x 0.64mm).
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