USB4624 datasheet(30/58 Pages) MICROCHIP

30 / 58 page

USB 2.0 HSIC Hi-Speed 4-Port Hub Controller

Datasheet

DS00001717A-page 30

 2014 Microchip Technology Inc.

6.2.2

SMBus Accessible Functions

6.2.2.1

OTP Access over SMBus

The device’s OTP ROM is accessible over SMBus. All OTP parameters can modified via the SMbus

Host. The OTP can be programmed to operate in Single-Ended, Differential, Redundant, or Differential

Redundant mode, depending on the level of reliability required. The supported commands are:



Enable OTP reset



Set OTP operating mode



Set OTP read mode



Program OTP



Get OTP Status



Program OTP control parameters

6.2.2.2

Configuration Access over SMBus

The following functions are available over SMBus prior to the hub attaching to the USB host:



Program Configuration parameters.



Program descriptor fields:

—Language ID

—Manufacturer string

—Product string

—idVendor

—idProduct

—bcdDevice



Program Control Register

6.3

Device Configuration Straps

Configuration straps are multi-function pins that are driven as outputs during normal operation. During

a Power-On Reset (POR) or an External Chip Reset (RESET_N), these outputs are tri-stated. The high

or low state of the signal is latched following de-assertion of the reset and is used to determine the

default configuration of a particular feature. Configuration straps are latched as a result of a Power-On

Reset (POR) or a External Chip Reset (RESET_N). Configuration strap signals are noted in Chapter 3,

"Pin Descriptions," on page 11 and are identified by an underlined symbol name. The following sub-

sections detail the various configuration straps.

Configuration straps include internal resistors in order to prevent the signal from floating when

unconnected. If a particular configuration strap is connected to a load, an external pull-up or pull-down

should be used to augment the internal resistor to ensure that it reaches the required voltage level

prior to latching. The internal resistor can also be overridden by the addition of an external resistor.

Note: The system designer must guarantee that configuration straps meet the timing requirements

specified in Section 9.5.2, "Reset and Configuration Strap Timing," on page 51 and Section

9.5.1, "Power-On Configuration Strap Valid Timing," on page 50. If configuration straps are not

at the correct voltage level prior to being latched, the device may capture incorrect strap

values.

Note: Configuration straps must never be driven as inputs. If required, configuration straps can be

augmented, or overridden with external resistors.

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