ꢀ ꢁꢂ ꢃ ꢄ ꢅ ꢆꢇ ꢀꢁ ꢂ ꢃ ꢄ ꢅ ꢈ
ꢂ
ꢀ
ꢁꢂ
ꢃ
ꢄ
ꢅ
ꢉ
ꢇ
ꢀ
ꢁ
ꢃ
ꢄ
ꢅ
ꢄ
www.ti.com
50% of V
SLES081A − JUNE 2003 – REVISED MAY 2004
LRCK (Output)
DD
DD
DD
t
(BCL)
t
t
t
(BCH)
(BL)
50% of V
BCK (Output)
t
(BCY)
t
(BD)
(LD)
DOUT (Output)
50% of V
t
(DS)
t
(DH)
DIN (Input)
SYMBOL
50% of V
DD
PARAMETER
MIN
300
MAX
UNIT
t
BCK pulse cycle time
ns
ns
ns
ns
ns
ns
ns
ns
(BCY)
t
BCK pulse duration, HIGH
BCK pulse duration, LOW
100
100
–20
–20
–20
20
(BCH)
t
(BCL)
t
LRCK delay time from BCK falling edge
DOUT delay time from BCK falling edge
DOUT delay time from LRCK edge
DIN setup time
40
40
40
(BL)
t
(BD)
t
(LD)
(DS)
(DH)
t
t
DIN hold time
20
NOTE: Load capacitance is 20 pF.
Figure 23. Audio Interface Timing
EXTERNAL ROM DESCRIPTOR (PCM2704/6)
The PCM2704/6 supports an external ROM interface to override internal descriptors. Pin 3 (for PCM2704)/pin 15
(for PCM2706) is assigned as DT (serial data) and pin 2 (for PCM2704)/pin 14 (for PCM2706) is assigned as CK
2
(serial clock) of the I C interface when using the external ROM descriptor. Descriptor data is transferred from the
2
external ROM to the PCM2704/6 through the I C interface the first time when the device activates after power-on
reset. Before completing a read of the external ROM, the PCM2704/6 replies with NACK for any USB command
request from the host to the device itself. The descriptor data, which can be in external ROM, are as follows. String
descriptors must be described in ANSI ASCII code (1 byte for each character). String descriptors are automatically
converted to unicode strings for transmission to the host. The device address of the external ROM is fixed as 0xA0.
The data must be stored from address 0x00 and must consist of 57 bytes as described in the following items. Read
operation is performed at a cycle of XTI/384 (approximately 30 kHz).
D
D
D
D
D
D
D
Vendor ID (2 bytes)
Product ID (2 bytes)
Device string (16 bytes in ANSI ASCII code)
Vendor string (32 bytes in ANSI ASCII code)
Maximum power (1 byte)
Power attribute (1 byte)
Auxiliary HID usage ID in report descriptor (3 bytes)
20
TI [ TEXAS INSTRUMENTS ]
