10.5 Power-Class Programming

The PC0–PC2 terminals are programmed to set the default value of the power-class indicated in the pwr field (bits 21–23) of the transmitted self-ID packet. Table 10−9 shows the descriptions of the various power classes. The default power-class value is loaded following a system (hardware) reset, but is overridden by any value subsequently loaded into the Pwr_Class field in register 4.

 

Table 10−9. Power Class Descriptions

PC0–PC2

DESCRIPTION

 

 

000

Node does not need power and does not repeat power.

 

 

001

Node is self-powered and provides a minimum of 15 W to the bus.

 

 

010

Node is self-powered and provides a minimum of 30 W to the bus.

 

 

011

Node is self-powered and provides a minimum of 45 W to the bus.

 

 

100

Node may be powered from the bus and is using up to 3 W. No additional power is needed to enable the link.

 

 

101

Reserved

 

 

110

Node is powered from the bus and uses up to 3 W. An additional 3 W is needed to enable the link.

 

 

111

Node is powered from the bus and uses up to 3 W. An additional 7 W is needed to enable the link.

 

 

10−7

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Texas Instruments PCI7611, PCI7411, PCI7621 Power-Class Programming, 9. Power Class Descriptions, PC0-PC2 Description, 10−7