UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
209 of 362
NXP Semiconductors
UM10208
Chapter 17: LPC2800 USB Device
4.
USB pin description
In addition to these signals there are 3 grounds, two 3.3V pads, and two 1.8V pads
associated with the USB and USB DMA facilities, with various pad names. In applications
that use the on-chip DC-DC converter, the power pads can be connected to outputs of the
DC-DC.
5.
Architecture
The architecture of the USB device controller is shown in
Table 231. USB interface pad description
Pin name
Type
Description
DP
I/O
USB D+ pin.
DM
I/O
USB D- pin.
VBUS
Input
USB VB+ sense. This pad acts as a voltage sensor rather than
a power pad.
CONNECT
Analog I/O
Used for signalling speed capability indication. For high speed
USB, connect a 1.5K resistor between this pad and 3.3V.
RREF
Reference
Transceiver reference. Connect a 12K 1% resistor between this
pad and ground.
DCDC_V
USB
Power
To use the DC-DC converter powered from the USB, connect
this pad directly to the USB VB+ line.
Fig 27. USB device controller block diagram
register
interface
(AHB slave)
DMA interface
(AHB master)
EP_RAM
(4K)
EP_RAM
ACCESS
CONTROL
REGISTER
INTERFACE
SERIAL
INTERFACE
ENGINE
DMA
ENGINE
USB DEVICE
BLOCK
US
B ATX
BUS
MASTER
INTERFACE
AH
B
BU
S