Datasheet

LPC11U6x All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 1.2 — 26 May 2014 76 of 96
NXP Semiconductors
LPC11U6x
32-bit ARM Cortex-M0+ microcontroller
One method is to use a voltage divider to connect the USB_VBUS pin to the VBUS on the
USB connector. The voltage divider ratio should be such that the USB_VBUS pin is
greater than 0.7 V
DD
to indicate a logic HIGH while below the 3.6 V allowable maximum
voltage.
For the following operating conditions
VBUS
max
= 5.25 V
V
DD
= 3.6 V,
the voltage divider should provide a reduction of 3.6 V/5.25 V or ~0.686 V.
The USB_CONNECT function can be enabled internally by setting the DCON bit in the
DEVCMDSTAT register to prevent the USB from timing out when there is a significant
delay between power-up and handling USB traffic. External circuitry is not required for the
USB_CONNECT functionality.
Fig 38. USB interface on a self-powered device where USB_VBUS = 5 V
LPC1xxx
V
DD
R1
1.5 kΩ
aaa-010820
USB-B
connector
USB_DP
USB_DM
USB_VBUS
V
SS
R
S
= 33 Ω
R
S
= 33 Ω
USB
USB_CONNECT
R2
R3
D+
D-