Integrated USB 2.0 Compatible 4-Port Hub

Datasheet

 

 

5.3.9.17

Register 10h: Power-On Time (Reset = 0x00)

 

 

 

BIT

 

 

NUMBER

BIT NAME

DESCRIPTION

 

 

 

7:0

POWER_ON_TIME

Power On Time: The length of time that it takes (in 2 ms intervals) from the

 

 

time the host initiated power-on sequence begins on a port until power is

 

 

good on that port.

 

 

 

5.3.9.18Undefined Registers

The registers shown in Table 5.4 are the defined registers in the Hub. Reads to undefined registers return 00h. Writes to undefined registers have no effect and do not return an error.

5.3.9.19Reserved Registers

Unless otherwise instructed, only a ‘0’ may be written to all reserved registers or bits.

5.4Default Configuration Option:

The SMSC Hub can be configured via its internal default configuration. (please see for specific details on how to enable default configuration.

Please refer to Table 5.1 on page 20 for the internal default values that are loaded when this option is selected.

5.5Default Strapping Options:

The SMSC Hub can be configured via a combination of internal default values and pin strap options. Please see Table 4.1, "7-Port Hub Pin Descriptions" for specific details on how to enable the default/pin-strap configuration option.

The strapping option pins only cover a limited sub-set of the configuration options. The internal default values will be used for the bits & registers that are not controlled by a strapping option pin. Please refer to Table 5.1 on page 20 for the internal default values that are loaded when this option is selected.

The Amber and Green LED pins are sampled after RESET_N negation, and the logic values are used to configure the hub if the internal default configuration mode is selected. The implementation shown below (see Figure 5.1) shows a recommended passive scheme. When a pin is configured with a “Strap High” configuration, the LED functions with active low signalling, and the PAD will “sink” the current from the external supply. When a pin is configured with a “Strap Low” configuration, the LED functions with active high signalling, and the PAD will “source” the current to the external LED.

SMSC USB2504/USB2504A

33

Revision 2.3 (08-27-07)

 

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