
Philips Semiconductors
PNX15xx Series
Volume 1 of 1
Chapter 18: SPDIF Input
PNX15XX_SER_3
Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet
Rev. 3 — 17 March 2006
18-14
SWS (Last subframe) - this event signal indicates that a single 32-bit subframe
corresponding to the last sample in the currently lling memory buffer has been
received at the input to SPDIF Input. The event is NOT qualied with a particular
block boundary. This represents a precise, periodic event for use by system
software to achieve audio/video synchronization.
All SPDI_STATUS register bits (except LOCK) - these events can be used by
software to either count or timestamp any interrupt generated by SPDIF Input.
Refer to
Table 6 for details regarding SPDIF Input interrupt sources.
4.
Signal Descriptions
4.1 External Interface Pins
The SPDIF Input module has a single input pin. The signal applied to this pin must
have TTL level voltage swing.
For the commonly found 0.5 Vpp SPDIF signal (IEC60958 consumer mode), the user
must externally restore the signal to TTL voltage levels. In all cases, external isolation
of the input signal is recommended.
4.1.1
System Interface Requirements
IEC60958 species that consumer systems have a 0.5 Vpp signal driven from the
transmitter into an unbalanced cable with a 75 ohm nominal impedance. The load
side must present a 75-ohm resistive impedance over the frequency band of
0.1 to 6 MHz.
Figure 8 presents an input circuit that satises the load requirements.
The circuit presents a simple RS422 differential receiver. The chosen receiver should
have good input hysteresis. Also, the signal applied to the SPDIF Input input pin
should ideally have a 50% duty cycle. It is recommended that the system designer
add an isolation transformer to the input circuit. Other consumer input circuits may be
possible.
Table 5: SPDIF Input Pin Summary
Signal
Type
Description
SPDI_IN
IN
Single-ended SPDIF Input pin. Input sample rate can be 32 kHz,
44.1 kHz, 48 kHz or 96 kHz. Input signal must be TTL compatible.
Figure 8:
SPDIF Input Consumer interface
SPDIF Input
RCA
0v
Vdd
Phono
+v
-v
+
-
RS-422 receiver
TTL output
with good input hysteresis
differential voltage swing is 0.5Vpp
75 ohm
0v
need 50% duty cycle