USB2512B datasheet(29/57 Pages) MICROCHIP

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 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 29

USB251xB/xBi

5.1.28

5.1.29

Bit Number

Bit Name

Description

7:6

BOOST_IOUT_4

USB electrical signaling drive strength boost bit for downstream port 4.

: normal electrical drive strength - no boost

: elevated electrical drive strength - low (~4% boost)

: elevated electrical drive strength - medium (~ 8% boost)

: elevated electrical drive strength - high (~12% boost)

5:4

BOOST_IOUT_3

USB electrical signaling drive strength boost bit for downstream port 3.

: normal electrical drive strength - no boost

: elevated electrical drive strength - low (~4% boost)

: elevated electrical drive strength - medium (~ 8% boost)

: elevated electrical drive strength - high (~12% boost)

3:2

BOOST_IOUT_2

USB electrical signaling drive strength boost bit for downstream port 2.

: normal electrical drive strength - no boost

: elevated electrical drive strength - low (~4% boost)

: elevated electrical drive strength - medium (~ 8% boost)

: elevated electrical drive strength - high (~12% boost)

1:0

BOOST_IOUT_1

USB electrical signaling drive strength boost bit for downstream port 1.

: normal electrical drive strength - no boost

: elevated electrical drive strength - low (~4% boost)

: elevated electrical drive strength - medium (~ 8% boost)

: elevated electrical drive strength - high (~12% boost)

Note:

Boost could result in non-USB compliant parameters. Therefore, a value of 00 should be implemented

unless specific implementation issues require additional signal boosting to correct for degraded USB sig-

naling levels.

Bit Number

Bit Name

Description

7:0

PRTSP

Port Swap: swaps the upstream USBDP/USBDM pins (USBDP_UP and

USBDM_UP) and the downstream USBDP/USBDM pins (USBDP_DN[x:1] and

USBDP_DN[x:1]) for ease of board routing to devices and connectors.

: USB D+ functionality is associated with the DP pin and D- functionality is

associated with the DM pin.

: USB D+ functionality is associated with the DM pin and D- functionality is

associated with the DP pin.

Bit 7 : rsvd

Bit 6 : rsvd

Bit 5 : rsvd

Bit 4 : controls port 4

Bit 3 : controls port 3

Bit 2 : controls port 2

Bit 1 : controls port 1

Bit 0 : when set to 1, the upstream port DP/DM is swapped.

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