XR21V1412IL-0A Datasheet, PDF (8/32 Pages) Exar Corporation – 2-CH FULL-SPEED USB UART

XR21V1412
2-CH FULL-SPEED USB UART
REV. 1.3.0
TABLE 2: REMOTE WAKEUP AND POWER MODES
SDA
SCL
REMOTE WAKE-UP
SUPPORT
POWER MODE
1
1
No
Self-Powered
1
0
No
Bus-Powered
0
1
Yes
Self-Powered
0
0
Yes
Bus-Powered
1.3.1 EEPROM Contents
If SDA and SCL are both logic ’1’, the V1412 device will first confirm if there is an external EEPROM attached
by attempting to read the first 8 locations of the ROM. If address 0x07 of the ROM contains the value 0x58 (as
specified in Table 3), the contents of the ROM are assumed to be valid. Otherwise the EEPROM will be
ignored and the SDA / SCL bits are used to indicate remote wakeup support and device power mode.
The I²C address must be 0xA0. An EEPROM can be used to override default Vendor IDs and Device IDs, as
well as other attributes and maximum power consumption. Exar provides an in-circuit EEPROM programming
utility through the USB interface using UART Control block 0x65. Refer to Table 5, “Control Blocks,” on
page 15. The EEPROM programming utility can be downloaded from the Exar website. These values are
uploaded from the EEPROM to the corresponding USB Standard Device Descriptor or Standard Configuration
Descriptor. For details of the USB Descriptors, refer to the USB 2.0 specifications.
TABLE 3: EEPROM CONTENTS
EEPROM
ADDRESS
CONTENTS
0
Vendor ID (LSB)
1
Vendor ID (MSB)
2
Product ID (LSB)
3
Product ID (MSB)
4
Device Attributes
5
Device Maximum Power
6
Reserved
7
Signature of 0x58 (’X’). If the signature is not correct, the contents of the EEPROM are ignored.
1.3.1.1 Vendor ID
The Vendor ID value replaces the idVendor field in the USB Standard Device Descriptor.
1.3.1.2 Product ID
The Product ID value replaces the idProduct field in the USB Standard Device Descriptor.
1.3.1.3 Device Attributes
The Device Attributes value replaces the bmAttributes field in the USB Standard Configuration Descriptor. The
default setting in the V1412 device is 0xA0. The bit field definitions are:
• Bit 7 is reserved - set to ’1’
8