8.4.2 SMBus Master Mode

SMBus master mode allows the DS250DF210 to program itself by reading directly from an external EEPROM. When using the SMBus master mode, the DS250DF210 reads directly from specific location in the external EEPROM. When designing a system for using the external EEPROM, the user must follow these specific guidelines:

• Maximum EEPROM size is 2048 Bytes
• Minimum EEPROM size for a single DS250DF210 with individual channel configuration is 305 Bytes (3 base header bytes + 12 address map bytes + 4 x 72 channel register bytes + 2 share register bytes; bytes are defined to be 8-bits)
• Set ENSMB = Float, for SMBus master mode
• The external EEPROM device address byte must be 0xA0
• The external EEPROM device must support 400kHz operation at 2.5V or 3.3V supply
• Set the SMBus address of the DS250DF210 by configuring the ADDR0 and ADDR1 pins

When loading multiple DS250DF210 devices from the same EEPROM, use these guidelines to configure the devices:

• Configure the SMBus addresses for each DS250DF210 to be sequential. The first device in the sequence must have an address of 0x30
• Daisy chain READ_EN_N and ALL_DONE_N from one device to the next device in the sequence so that they do not compete for the EEPROM at the same time.
• If all of the DS250DF210 devices share the same EEPROM channel and share register settings, configure the common channel bit in the base header to 1. With common channel configuration enabled, each DS250DF210 device configures all channels with the same settings.

When loading a single DS250DF210 from an EEPROM, use these guidelines to configure the device:

• Set the common channel bit to 0 to allow for individual channel configuration, or set the common channel bit to 1 to load the same configuration settings to all channels.
• When configuring individual channels, a 1024 or 2048 Byte EEPROM must be used.
• If there are more than three DS250DF210 devices on a PCB that require individual channel configuration, then each device must have its own EEPROM.