Microchip Technology AT73C213B

Overview

AT73C213B from Atmel (now Microchip Technology) is a fully integrated stereo audio DAC and mono AB-class audio power amplifier IC designed for portable Li-ion/Ni-Mh battery-powered devices. It delivers 93 dB SNR playback, 32 Ω/20 mW stereo headset drivers with master volume/mute, and 440 mW output into 8 Ω at 3.6 V - enabling compact, low-component-count audio subsystems in mobile handsets and music players.

For engineers reviewing the AT73C213B datasheet, AT73C213B pinout, AT73C213B application, or AT73C213B equivalent, key selection considerations include its dual-mode amplifier (high/low-power), programmable 20-bit I²S interface, SPI-configurable gain/volume across all signal paths (DAC, line-in, aux, PA), and integrated analog mixing of stereo line inputs and differential mono auxiliary input.

Technical Context

The AT73C213B integrates two independent signal chains: a high-fidelity 20-bit sigma-delta stereo DAC with multibit modulation, dithering, and cascaded half-band + SINC interpolation filters (8× oversampling), plus a digitally controlled mono AB-class power amplifier with differential input/output, programmable gain (–22 to +20 dB), and <2 µA power-down current. Both sections share a common analog reference architecture using VREF, VCM, and AVDDHS decoupling.

Audio routing is managed via an on-chip digital mixer supporting simultaneous playback from DAC output, stereo line inputs (LINEL/LINER), and differential mono auxiliary input (AUXP/AUXN), with per-path analog gain control and mute. All digital configuration-including sampling rate (8–48 kHz), master clock ratio (256×/384× Fs), de-emphasis, and data format (I²S/MSB/LSB justified)-is performed over a 4-wire SPI bus.

Key Specifications

Pinout & Package

AT73C213B is housed in a 33-pin QFN package (5 mm × 5 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are validated per Atmel document 6407A–PMAAC–22-Apr-08.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar stereo audio DAC + mono amplifier applications.

Compared with AK4413VN and TPA6138A2, the AT73C213B uniquely combines 20-bit DAC, multi-source analog mixer, and configurable mono PA in one QFN package - offering lowest component count and smallest footprint for cost-sensitive portable audio designs requiring both playback and speaker drive.

Availability

AT73C213B is available at Aetrix Electronics and suitable for smartphone audio subsystems, DECT phone base stations, digital still camera playback, and portable music players requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for AT73C213B includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Atmel Corporation, now part of Microchip Technology, is a global semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and mixed-signal ICs for embedded and portable applications.

The AT73C213B belongs to Atmel's Power Management and Analog Companions (PMAAC) product line, engineered specifically to reduce system-level audio BOM count and simplify PCB layout in battery-powered handheld devices.

FAQ

What is the maximum sampling frequency supported by the AT73C213B?

The AT73C213B supports standard audio sampling rates up to 48 kHz, including 8, 11.024, 16, 22.05, 24, 32, 44.1, and 48 kHz. Its internal digital filter and sigma-delta modulator are optimized for these rates, with master clock options of 256× or 384× Fs to accommodate jitter-sensitive applications. The AT73C213B does not support rates above 48 kHz.

Does the AT73C213B include a built-in microphone preamplifier?

No, the AT73C213B does not include a dedicated microphone preamplifier. It provides stereo line-level inputs (LINEL/LINER), a differential mono auxiliary input (AUXP/AUXN), and DAC playback paths - all configurable via SPI registers for gain and mute. For microphone interfacing, an external bias circuit or preamp is required before connecting to the AUX or line inputs. The AT73C213B itself handles only line-level signal conditioning.

Can the AT73C213B drive both headphones and a loudspeaker simultaneously?

Yes, the AT73C213B can drive headphones and a loudspeaker concurrently: stereo headset drivers (HSL/HSR) support 32 Ω loads, while the mono power amplifier (HPN/HPP) drives 8 Ω speakers. However, they operate on separate signal paths - the DAC output may be routed to both via the digital mixer, but independent volume control and mute settings must be configured per path using SPI registers DAC_OLC and PA_CTRL. The AT73C213B does not share output stages between them.

What is the purpose of the VCM and VREF pins on the AT73C213B?

VCM (Pin 9) provides the common-mode reference voltage for analog input and output stages, typically set to 0.5 × AVDD; it requires a decoupling capacitor (10 µF or 100 µF, selected via SPI register VCMCAPSEL). VREF (Pin 1) is the precision voltage reference for the DAC's analog output stage and must be decoupled with a 10 µF ceramic capacitor. Both pins stabilize DC operating points and suppress supply-induced noise - critical for achieving the AT73C213B's specified 93 dB SNR and <0.1% THD+N.

Is the AT73C213B compatible with 1.8 V digital I/O systems?

No, the AT73C213B digital I/Os (SDIN, BCLK, LRFS, MCLK, SPI lines) are referenced to VDIG and specified for 2.4 V to 3.3 V operation only. Input high threshold is 0.8 × VDIG, and input low threshold is 0.2 × VDIG - meaning at 1.8 V supply, VIH would be 1.44 V (exceeding typical 1.8 V logic high of 1.62 V), risking unreliable detection. To interface with 1.8 V hosts, level-shifting circuitry is required. The AT73C213B itself does not support 1.8 V native I/O.