Datasheet

USB251xB/xBi
DS00001692C-page 28  2010 - 2015 Microchip Technology Inc.
5.1.26 REGISTER D0H: BATTERY CHARGING ENABLE
5.1.27 REGISTER F6H: BOOST_UP
Bit Number Bit Name Description
7:0 BC_EN Battery Charging Enable: enables the battery charging feature for the
corresponding port.
0 : battery charging support is not enabled
1 : battery charging support is enabled
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 : rsvd
Bit Number Bit Name Description
7:2 rsvd
1:0 BOOST_IOUT USB electrical signaling drive strength boost bit for the upstream port.
00 : normal electrical drive strength - no boost
01 : elevated electrical drive strength - low (~ 4% boost)
10 : elevated electrical drive strength - medium (~ 8% boost)
11 : 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
signalling levels.