USB5533B datasheet(18/71 Pages) MICROCHIP

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USB5533B

DS00001680C-page 18

 2012 - 2015 Microchip Technology Inc.

4.2

SMBus Slave Interface

Next, the USB5533B will look to receive configuration and commands from an optional SMBus master (if present). When

SMBus is enabled, the SMBus can operate in either legacy (USB 2.0 only) or advanced mode (access to both USB 2.0

and 3.0 registers). Next, the USB5533B will look for (optional) configuration present in the internal OTP memory. Any

The SMBus slave interface is enabled when pull-up resistors are detected on both SM_DAT and SM_CLK for the first

millisecond after reset. For operation in SMBus Legacy Mode, an additional pull-up resistor is required on TRST. If the

SMBus interface is enabled, then the USB5533B will wait indefinitely for the SMBus host to configure the device. Once

SMBus configuration is complete, device initialization will proceed. To disable the SMBus, a pull-down resistor of 10 K



must be applied to either SM_DAT, SM_CLK, or both SM_DAT and SM_CLK if desired. If SMBus is disabled, the device

proceeds directly to device initialization using the internal OTP ROM.

4.2.1

PULL-UP RESISTOR FOR SMBUS

External pull-up resistors (10 k

 recommended) are required on the SM_DAT and SM_CLK pins when implementing

either SMBus mode.

FIGURE 4-9:

SPI JEDEC-ID SEQUENCE

SPI_CEN

SPI_CLK

SPI_DO

SPI_DI

MSB

HIGH IMPEDANCE

11 12 13 14 15 16

12 3 4

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

MSB

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