CS4201 Datasheet, PDF (61/68 Pages) Cirrus Logic – CrystalClear Audio Codec 97 with headphone Amplifier

CS4201
Clock and Configuration Pins
XTL_IN - Crystal Input/Clock Input, Pin 2
This pin requires either a 24.576 MHz crystal, with the other pin attached to XTL_OUT, or an external
CMOS clock. XTL_IN must have a crystal or clock source attached for proper operation except when
operating in secondary codec mode. The crystal frequency must be 24.576 MHz and designed for
fundamental mode, parallel resonance operation. If an external CMOS clock is used to drive this pin, it
must run at one of these acceptable frequencies: 14.31818. 24.576, 27, or 48 MHz. When configured as
a secondary codec, all timing is derived from the BIT_CLK input signal and this pin should be left
floating. See Section 9, Clocking, for additional details.
XTL_OUT - Crystal Output/ PLL Loop Filter, Pin 3
This pin is used for a crystal placed between this pin and XLT_IN. If an external 24.576 MHz clock is
used on XTL_IN, this pin must be left floating with no traces or components connected to it. If one of
the other acceptable clocks is used on XTL_IN, this pin must be connected to a loop filter circuit. See
Section 9, Clocking, for additional details.
ID1#, ID0# - Codec ID, Inputs, Pins 45 and 46
These pins select the Codec ID for the CS4201, as well as determine the rate of the incoming clock in
PLL mode. They are only sampled after the rising edge of RESET#. These pins are internally pulled up
to the digital supply voltage and should be left floating for logic ‘0’ or tied to digital ground for logic ‘1’.
Misc. Digital Interface Pins
SPDO/SDO2 - Sony/Philips Digital Interface / Serial Data Output 2,Output, Pin 48
This pin generates the S/PDIF digital output from the CS4201 when the SPEN bit in the S/PDIF Control
Register (Index 68h) is ‘set’. This output may be used to directly drive a resistive divider and coupling
transformer to an RCA-type connector for use with consumer audio equipment. This pin also provides
the serial data for the second serial data port when the SDO2 bit in the Serial Port Control Register
(Index 6Ah) is ‘set’. These two functions are mutually exclusive. When neither function is being used
this output is driven to a logic ‘0’.
EAPD/SCLK - External Amplifier Powerdown / Serial Clock, Output, Pin 47
This pin is used to control the powerdown state of an audio amplifier external to the CS4201. The
output is controlled by the EAPD bit in the Powerdown Ctrl/Stat Register (Index 26h). It is driven as a
normal CMOS output and defaults low (‘0’) upon power-up. This pin also provides the serial clock for
both serial data ports when the SDSC bit in the Serial Port Control Register (Index 6Ah) is ‘set’.
GPIO0/LRCLK - General Purpose I/O / Left-Right Clock, Input/Output, Pin 43
This pin is a general purpose I/O pin that can be used to interface with various external circuitry. When
configured as an input, it functions as a Schmitt triggered input with 350 mV hysteresis at 5 V and 220
mV hysteresis at 3.3 V. When configured as an output, it can function as a normal CMOS output (4 mA
drive) or as an open drain output. This pin also provides the L/R clock for both serial data ports when
the SDEN bit in the Serial Port Control Register (Index 6Ah) is ‘set’. This bit powers up in the high
impedance state for backward compatibility.
DS483PP3
61