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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
644 of 1441
NXP Semiconductors
UM10503
Chapter 25: LPC43xx/LPC43Sxx USB0 Host/Device/OTG controller
25.5.1 Requirements for connecting the USB0_VBUS/USB1_VBUS signal
The USB0_VBUS and USB1_VBUS pins are only 5 V tolerant when VDDIO is present.
Therefore, special precautions are necessary when the USB0 controller is implemented
as a USB-powered USB device or an OTG product.
For a USB OTG product, it is important to be able to detect the VBUS level and to charge
and discharge VBUS. This requires adding active devices that disconnect the link when
VDDIO is not present.
For self-powered USB products that only use USB0 and that do not run in OTG mode,
USB0_VBUS can be left disconnected as long as the VC bit in the OTGSC register is set.
When this bit is set a voltage is applied to the USB0_VBUS pin internally which is the
equivalent of connecting the pin to a 5 V VBUS supply. Keeping the USB0_VBUS
disconnected, ensures that OTG VBUS line pulsing does not go towards the cable.
25.6 Register description
USB0_VBUS
I
VBUS pin (power on USB cable). This pin includes an internal pull-down resistor of
64 kOhm (typical) ± 16 kOhm. For maximum load C
L
= 6.5 uF and maximum
pull-down resistor R
pd
= 80 kOhm, the VBUS signal takes about 2 s to fall from
VBUS = 5 V to VBUS = 0.2 V when it is no longer driven.
Remark:
This input is only 5 V tolerant when VDDIO is present.
USB0_ID
I
Indicates to the transceiver whether connected as an A-device (USB0_ID LOW) or
B-device (USB0_ID HIGH). For OTG this pin has an internal pull-up resistor.
USB0_RREF
-
12.0 k
(accuracy 1%) on-board resistor to ground for current reference;
USB0_VDDA3V3_
DRIVER
-
Separate analog 3.3 V power supply for driver.
USB0_VDDA3V3
-
USB 3.3 V separate power supply voltage
USB0_VSSA_TERM
-
Dedicated analog ground for clean reference for termination resistors.
USB0_VSSA_REF
-
Dedicated clean analog ground for generation of reference currents and voltages.
Table 460. USB0 pin description
Pin function
Direction
Description
Table 461. Register access abbreviations
Abbreviation
Description
R/W
Read/Write
R/WC
Read/Write one to Clear
R/WO
Read/Write Once
RO
Read Only
WO
Write Only
R/WS
Read/Write one to Set