UDA1355H

General description

The UDA1355H is a single-chip IEC 60958 decoder and encoder with integrated stereo digital-to-analog converters and analog-to-digital converters employing bitstream conversion techniques.

The UDA1355H has a selectable one-of-four SPDIF input (accepting level I, II and III timing) and one SPDIF output which can generate level II output signals with CMOS levels. In microcontroller mode the UDA1355H offers a large variety of possibilities for defining signal flows through the IC, offering a flexible analog, digital and SPDIF converter chip with possibilities for off-chip sound processing via the digital input and output interface.

A lock indicator is available on pin LOCK when the IEC 60958 decoder and the clock regeneration mechanism is in lock. By default the DAC output and the digital data interface output are muted when the decoder is not in lock.

The UDA1355H contains two clock systems which can run at independent frequencies, allowing to lock-on to an incoming SPDIF or digital audio signal, and in the mean time generating a stable signal by means of the crystal oscillator for driving, for example, the ADC or SPDIF output signal.

Using the crystal oscillator (which requires a 12.288 MHz crystal) and the on-chip low jitter PLL, all standard audio sampling frequencies (f_s = 32, 44.1 and 48 kHz including half and double these frequencies) can be generated.

Features

1.1 General

• 2.7 to 3.6 V power supply
• Integrated digital interpolator filter and Digital-to-Analog Converter (DAC)
• 24-bit data path in interpolator
• No analog post filtering required for DAC
• Integrated Analog-to-Digital Converter (ADC), Programmable Gain Amplifier (PGA) and digital decimator filter
• 24-bit data path in decimator
• Master or slave mode for digital audio data I/O interface
• I²S-bus, MSB-justified, LSB-justified 16, 18, 20, and 24 bits formats supported on digital I/O interface.

1.2 Control

• Controlled by means of static pins or microcontroller (L3-bus or I²C-bus) interface.

1.3 IEC 60958 input

• On-chip amplifier for converting IEC 60958 input to CMOS levels
• Supports level I, II and III timing
• Selectable IEC 60958 input channel, one of four
• Supports input frequencies from 28 to 96 kHz
• Lock indication signal available on pin LOCK
• 40 status bits can be read for left and right channel via L3-bus or I²C-bus
• Channel status bits available via L3-bus or I²C-bus: lock, pre-emphasis, audio sample frequency, two channel Pulse Code Modulation (PCM) indication and clock accuracy
• Pre-emphasis information of incoming IEC 60958 bitstream available in register
• Detection of digital data preamble, such as AC3, available on pin in microcontroller mode.

1.4 IEC 60958 output

• CMOS output level converted to IEC 60958 output signal
• Full-swing digital signal, with level II timing using crystal oscillator clock
• 32, 44.1 and 48 kHz output frequencies supported in static mode
• 32, 44.1 and 48 kHz output frequencies (including double and half of these frequencies) supported in microcontroller mode
• Via microcontroller, 40 status bits can be set for left and right channel.

1.5 Digital I/O interface

• Supports sampling frequencies from 16 to 100 kHz
• Supported static mode:
• I²S-bus format
• LSB-justified 16 and 24 bits format
• MSB-justified format.
• Supported microcontroller mode:
• I²S-bus format
• LSB-justified 16, 18, 20 or 24 bits format
• MSB-justified format.
• BCK and WS signals can be slave or master, depending on application mode.

1.6 ADC digital sound processing

• Supports sampling frequencies from 16 to 100 kHz
• Analog front-end includes a 0 to +24 dB PGA in steps of 3 dB, selectable via microcontroller interface
• Digital independent left and right volume control of +24 to -63.5 dB in steps of 0.5 dB via microcontroller interface
• Bitstream ADC operating at 64f_s
• Comb filter decreases sample rate from 64f_s to 8f_s
• Decimator filter (8f_s to f_s ) made of a cascade of three FIR half-band filters.

1.7 DAC digital sound processing

• Digital de-emphasis for 32, 44.1, 48 and 96 kHz audio sampling frequencies
• Automatic de-emphasis when using IEC 60958 to DAC
• Soft mute made of a cosine roll-off circuit selectable via pin MUTE or L3-bus interface
• Programmable digital silence detector
• Interpolating filter (f_s to 64f_s or f_s to 128f_s ) comprising a recursive and a FIR filter in cascade
• Selectable fifth-order noise shaper operating at 64f_s or third-order noise shaper operating at 128f_s (specially for low sampling frequencies, e.g. 16 kHz) generating bitstream for DAC
• Filter Stream DAC (FSDAC)
• In microcontroller mode:
• Left and right volume control (for balance control) 0 to-78 dB and -∞
• Left and right bass boost and treble control
• Optional resonant bass boost control
• Mixing possibility of two data streams.

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