PCM2704,PCM2705

PCM2706,PCM2707

SLES081A − JUNE 2003 – REVISED MAY 2004

www.ti.com

20

t(BCH)

DOUT (Output)

t(BCL)

t(BL)

t(BCY)

50% of VDD

50% of VDD

50% of VDD

LRCK (Output)

BCK (Output)

DIN (Input)

t(DH)

t(DS)

50% of VDD

t(BD)

t(LD)

SYMBOL

PARAMETER

MIN

MAX

UNIT

t(BCY)

BCK pulse cycle time

300

ns

t(BCH)

BCK pulse duration, HIGH

100

ns

t(BCL)

BCK pulse duration, LOW

100

ns

t(BL)

LRCK delay time from BCK falling edge

–20

40

ns

t(BD)

DOUT delay time from BCK falling edge

–20

40

ns

t(LD)

DOUT delay time from LRCK edge

–20

40

ns

t(DS)

DIN setup time

20

ns

t(DH)

DIN hold time

20

ns

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

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).