NSA20921

NSA20921 is a high-voltage, high-performance Class-D audio power amplifier driver IC designed for Class-D audio amplifier systems with ultra-high output power. It integrates an analog power amplifier, PWM modulation circuit, high- and low-side overcurrent protection (for both high- and low-side power devices), shoot-through prevention dead-time logic, and three voltage domains (VAA~VSS / VCC~COM / VB~VS), adopting a flexible open-loop topology to implement PWM modulation. NSA20921 integrates a pop-click suppression function during startup and shutdown to eliminate unwanted audible noise when the PWM signal is turned on or off. Combined with a power bridge circuit and a few passive components, it enables a complete Class-D audio power amplifier. NSA20921 is a high-power Class-D audio amplifier driver IC integrating a PWM modulator and overcurrent protection. Paired with two external power MOSFETs and a few passive components, it forms a complete Class-D audio power amplifier with high- and low-side overcurrent protection, shoot-through protection, and undervoltage protection. The error amplifier analog input is versatile, and the PWM modulation circuit is flexible and adjustable, supporting multiple PWM modulation schemes. The device detects overcurrent in power devices by sensing the MOSFET Rds(on), eliminating the conventional direct current sensing approach, thereby simplifying the system architecture and reducing application complexity. To match the bridge output topology, the analog PWM modulator and protection logic are placed in a floating well, and the high-side circuitry is also placed in a floating well; the breakdown voltage between the floating well and the chip substrate ground (COM) exceeds 200V, supporting amplifier applications up to ±150V and enabling output power exceeding 500W. NSA20921 also integrates a pop-click noise suppression circuit to eliminate noise caused during the startup and shutdown phases of the PWM modulation waveform.

Applications

• Home theater systems
• Stereo mini component systems
• Active speaker systems
• General-purpose audio power amplifiers

Key features

• Class-D power amplifier with integrated analog signal input
• Power amplifier open-loop gain >60dB
• Integrated overcurrent protection on both high-side and low-side with auto-recovery
• External 5V reference voltage output; low-side overcurrent protection threshold programmable
• Programmable timing for protection signal duration
• Programmable preset dead time for improved THD performance
• 25ns @ DT pin voltage >0.57V
• 40ns @ 0.57V > DT pin voltage > 0.36V
• 65ns @ 0.36V > DT pin voltage > 0.23V
• 105ns @ 0.23V > DT pin voltage > 0V
• Integrated "click and pop" suppression during power-on and power-off
• Integrated multi-voltage domain UVLO and overvoltage clamp protection
• High transient noise immunity (CMTI): >50V/ns
• Output swing up to ±100V, supporting output power exceeding 500W
• Maximum operating frequency: 800KHz
• Wide temperature range: -40℃ to 125℃
• Switching parameters:
• 360ns/335ns typical propagation delay
• 500ns maximum overcurrent protection delay
• 250ns maximum enable control delay
• Load output source/sink current capability up to 1A/1.2A
• RoHS-compliant SOP16 (S)