QT2022/32 - Data Sheet: DS3051
Figure 30: QT2022/32 DOM Application Diagram
3.3 V
EEPROM_SDA
EEPROM_SCL
address
1010000
QT2032/
QT2022
EEPROM
DOM
device
address
1010xxx
The EEPROM and DOM are at different device addresses.
The current 256 NVR registers will continue to be read from an external EEPROM with device address 1010000.
NVR register mapping and update control conform to the XENPAK MSA.
MDIO device number 1 is used for the NVR registers and DOM registers on QT2022/32.
The presence of an external DOM device is indicated by NVR register 1.807Ah.6. This bit must be set to 1 to
enable the QT2022/32 DOM logic. The lower 3 bits of the DOM device address are read from NVR register
1.807Ah.2:0 (defaults to 001 after reset). The upper 4 device address bits are hardwired to 1010. The DOM device
address must be in the range 1010001x to 1010111x.
The default frequency of the serial interface clock, EEPROM_SCL, is 37kHz. This will result in an upload time of
approximately 62ms for 256 bytes assuming for no wait times for the DOM device to respond. Clock stretching is
supported.
Refer to Section 18.10, “DOM Memory Behavior,” on page 216 for details on DOM Memory usage.
10.5.1 DOM Upload on Reset
Both the NVR and DOM registers are set to their default values by a hardware or software reset. The NVR regis-
ters are automatically uploaded after a reset is applied to the QT2022/32. The upload begins 250 ms after the reset
function is completed. This delay is to allow the external devices time to stabilize after power up. After the NVR reg-
isters are successfully uploaded, and if a DOM device is present, the DOM registers will be uploaded. The DOM
update frequency defaults to a single upload (1.A100h.1:0=00). If a reset occurs in the middle of a DOM or
EEPROM transaction, the transaction is stopped immediately, the QT2022/32 releases the EEPROM_SDA pin and
drives the EEPROM_SCL pin high.
The EEPROM and DOM upload sequence is presented in figure 36 on page 92.
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