Table 7-15. Bias Register (Channel register base + Offset = 0x06) (continued)

Bit

Field

Type

Reset

Description

7,6,2-0

Reserved

R/W

0x00000

Reserved

7.5.3 SMBus/I2C Primary Mode Configuration (EEPROM Self Load)

The DS320PR810 can also be configured by reading from EEPROM. To enter into this mode MODE pin

must be set to L1. The EEPROM load operation only happens once after the device's initial power-up. If the

DS320PR810 is configured for SMBus Primary mode, then it will remain in the SMBus IDLE state until the

READ_EN_N pin is asserted to LOW. After the READ_EN_N pin is driven LOW, the DS320PR810 becomes an

SMBus primary and attempts to self-configure by reading the device settings stored in an external EEPROM

(SMBus 8-bit address 0xA0). When the DS320PR810 has finished reading from the EEPROM successfully, it

will drive the ALL_DONE_N pin LOW. SMBus/I2C secondary operation is available in this mode before, during,

or after EEPROM reading. Note: during EEPROM reading, if the external SMBus/I2C primary wants to access

DS320PR810 registers, then it must support arbitration.

When designing a system for using the external EEPROM, the user must follow these specific guidelines:

• EEPROM size of 2 kb (256 × 8-bit) is recommended.

• Set MODE = L1, configure for SMBus Primary mode.

• The external EEPROM device address byte must be 0xA0 and capable of 400 kHz operation at 3.3 V supply

• In SMBus/I2C modes the SCL and SDA pins must be pulled up to a 3.3 V supply with a pull-up resistor.

The value of the resistor depends on total bus capacitance. 4.7 kΩ is a good first approximation for a bus

capacitance of 10 pF.

Figure 7-1 shows a use case with four DS320PR810 to implement a PCIe x16 configuration, but the user can

cascade any number of DS320PR810 devices in a similar way. Tie the READ_EN_N pin of the first device low to

automatically initiate EEPROM read at power up. Alternatively, the READ_EN_N pin of the first device can also

be controlled by a micro-controller to initiate the EEPROM read manually. Leave the ALL_DONE_N pin of the

final device floating, or connect the pin to a micro-controller input to monitor the completion of the final EEPROM

read.

Figure 7-1. Daisy Chain Four DS320PR810 Devices to Read from Single EEPROM in x16 Configuration

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DS320PR810

SNLS668 – AUGUST 2022

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