USB3503 datasheet(36/73 Pages) MICROCHIP

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USB3503

DS00001584B-page 36

 2011-2015 Microchip Technology Inc.

6.0

SERIAL SLAVE INTERFACE

6.1

Overview

The serial slave interface on USB3503 is implemented as I2C. It is a standard I2C slave interface that operates at the

standard (100Kbps), fast (400Kbps), and the fast mode plus (1Mbps) modes.

The USB3503 I2C slave interface address is 0x08h.

REFCLK must be running for I2C to operate. The register map is outlined in section Section 5.3.

The I2C Slave Base Address is 0x08. The interrupt pin INT_N is used to communicate status changes on selected

events that are mapped into the Serial Port Interrupt Status Register. INT_N is asserted low whenever an unmasked bit

is set in the Serial Port Interrupt Status Register. SOC must update the Serial Port Interrupt Status Register to negate

the interrupt high.

The SOC can mask events to not cause the interrupt pin to transition by updating the Serial Port Interrupt Mask Register.

The status events will still be captured in the status register even if the interrupt pin is not asserted. The serial port has

limited speed and latency capability so events mapped into the serial ports and its interrupt are not expected to be

latency critical.

6.2

Interconnecting the USB3503 to an I2C Master

Note 6-1

The largest pullup values which meet the customer application should be selected in order to

minimize power consumption. Pullup values must also have low enough resistance to support the

desired i2C operating speed with the expected total capacitance in the application. Typical

applications are expected to use pullup values between 220Ω and 2.7kΩ for operation at 1MHz on

SCL and SDA. Larger pullup resistors may be acceptable for operation at 400KHz or 100KHz.

FIGURE 6-1:

I2C CONNECTIONS

I2C

MASTER

CONTROLLER

USB3503

SCL

SDA

SOC

SCL

SDA

VDD

INT

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