Cirrus Logic CS35L32-CWZR

The CS35L32 is a low-quiescent power-integrated audio IC, with a mono full-bridge Class D speaker amplifier operating with a self-boosted Class G supply. Audio input is received differentially. Pop-and-click reduction is achieved with zerocrossing transitions at turn-on, turn-off and upon gain changes. Communication with the host processor is done using an I2C interface. In addition, an I2S bus is used to send monitor and status data. When two CS35L32 devices are available on the same board, each is identified by its I2C chip address. Upon power-up or upon deasserting RESET, each CS35L32 reads the AD0 pin logic level and configures its I2C device address. The speaker amplifier, using closed-loop delta-sigma modulation, achieves low levels of distortion. Class D amplifier efficiency allows operation at higher speaker power levels without generating excessive heat and without wasting power. Automatic Class G operation using a boosted supply to the speaker allows for even higher powers and higher crest factor. With a boosted speaker supply, operation at a fixed 5 V is achieved independently of line supplied battery voltage. The user can disable Class G operation. The battery voltage, speaker voltage, and speaker current signals are monitored, digitized using delta-sigma converters, and serialized over an I2S bus. The speaker monitoring signals are part of a speaker-protection algorithm that is managed externally to the CS35L32. Outgoing data is sent over I2S with the CS35L32 in Slave or Master Mode. Battery voltage monitor data is accessible through I2C. An integrated dual LED driver operates up to two LEDs in Flash Mode or Movie Mode. A flash event is triggered by an external signal. A flash-inhibit event is triggered by an external signal, and causes a reduction in flash current. A timer is provided for flash and flash inhibit events. Movie Mode operation has no timer and starts and ends via an I2C command. Flash and Movie Mode current levels, as well as the flash timer are I2C programmable. Total power consumption when powering LEDs in Flash Mode or Movie Mode, and powering audio simultaneously, is managed by the user’s choices in programming the current limit and in power budgeting. The primary goal is to manage audio and LED loads so the boost converter is not current limited and so the CS35L32 does not shut down due to overheating. A latched shutdown of the audio amplifier occurs in the event of an output short pin to ground, pin to supply, or pin to pin. A latched shutdown of the CS35L32 also occurs on overtemperature. An LED driver shutdown occurs in

• Two-level Class G operation: Boosted: 5 V nominal; Bypassed: battery voltage is supplied directly
• 2.5 mA quiescent current, monitors powered down
• 1.7 W into 8 Ω (@ 10% THD+N)
• 102-dB signal-to-noise ratio (SNR, A-weighted)
• Idle channel noise 25 μVrms (A-weighted)
• 90% efficiency
• One differential analog input
• Speaker gain: 9, 12, 15, and 18 dB and mute; Pop suppression, zero-crossing detect transitions
• Integrated dual LED drivers using the following: Boost supply output voltage; Dual matched current regulators, 750 mA max each
• Programmable setting for Flash Mode current: 50 - 750 mA, in 50-mA steps
• Programmable setting for Flash-Inhibit Mode current: 50–350 mA, in 50-mA steps
• Programmable setting for Movie Mode current: 150, 120, 100, 80, 60, 40, 20 mA
• Programmable flash timer setting: 50–500 ms, in 25-ms steps
• Dedicated pin for flash trigger (FLEN)
• Dedicated pin for flash inhibit (FLINH)
• Thermally managed through boost-voltage regulation
• Latched overtemperature shutdown
• Latched amplifier output short circuit shutdown
• LED short or open detection and LED driver shutdown
• Flash inhibit LED current reduction
• Low battery flash LED current reduction
• VP undervoltage lockout (UVLO) shutdown
• Programmable boost inductor current limiting
• Audio and LED shutdown upon stopped MCLK, with autorecovery
• Interrupt driven error reporting
• Speaker current and voltage monitoring: 16-bit resolution; 60-dB dynamic range (unweighted) for voltage; 56-dB dynamic range (unweighted) for current; Bused over I2S bus
• Battery voltage monitoring: 7-bit resolution; Bused over I2S and I2C bus
• System reset
• Low-power standby
• LED and audio power budgeting programmable settings
• Boost inductor current limit programmable setting
• Speaker programmable settings: Pop suppression through zero-crossing transitions; Gain and mute
• Battery voltage monitor register, 8 bits
• LED driver programmable settings: Flash current register; Flash inhibit current register; Movie Mode current register; Flash timer register
• Error status bit, including the following: Stopped MCLK error; Low battery detection with programmable thresholds; VP UVLO error; Overtemperature warning; Overtemperature error; Boost converter overvoltage error; Boost inductor current-limiting error; Amplifier short-circuit error; Shorted or open LED error
• Monitoring: Speaker voltage monitor; Speaker current monitor; Battery voltage monitor; VP UVLO shutdown error; Overtemperature warning; Overtemperature error; Boost converter overvoltage error; Boost inductor current limiting error; Amplifier short-circuit error; Speaker voltage monitor overflow error; Speaker current monitor overflow error; Battery voltage monitor overflow error
• Status reporting: Power-down done; LED flash event; LED Movie Mode event; Flash timer on

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