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 75 of 96
NXP Semiconductors
LPC11U6x
32-bit ARM Cortex-M0+ microcontroller
14. Application information
14.1 ADC usage notes
The following guidelines show how to increase the performance of the ADC in a noisy
environment beyond the ADC specifications listed in Table 22
:
• The ADC input trace must be short and as close as possible to the LPC11U6x chip.
• The ADC input traces must be shielded from fast switching digital signals and noisy
power supply lines.
• If the ADC and the digital core share a power supply, the power supply line must be
adequately filtered.
• To improve the ADC performance in a very noisy environment, put the device in Sleep
mode during the ADC conversion.
14.2 Typical wake-up times
[1] The wake-up time measured is the time between when a GPIO input pin is triggered to wake up the device
from the low-power modes and from when a GPIO output pin is set in the interrupt service routine (ISR)
wake-up handler.
[2] IRC enabled, all peripherals off.
[3] WatchDog oscillator disabled, Brown-Out Detect (BOD) disabled.
[4] Wake-up from deep power-down causes the part to go through entire reset process. The wake-up time
measured is the time between when a wake-up pin is triggered to wake up the device from the low-power
modes and when a GPIO output pin is set in the reset handler.
14.3 Suggested USB interface solutions
The USB device can be connected to the USB as self-powered device (see Figure 38) or
bus-powered device (see Figure 39
).
On the LPC11U6x, the PIO0_3/USB_VBUS pin is 5 V tolerant only when V
DD
is applied
and at operating voltage level. Therefore, if the USB_VBUS function is connected to the
USB connector and the device is self-powered, the USB_VBUS pin must be protected for
situations when V
DD
= 0 V.
If V
DD
is always at operating level while VBUS = 5 V, the USB_VBUS pin can be
connected directly to the VBUS pin on the USB connector.
For systems where V
DD
can be 0 V and VBUS is directly applied to the VBUS pin,
precautions must be taken to reduce the voltage to below 3.6 V, which is the maximum
allowable voltage on the USB_VBUS pin in this case.
Table 25. Typical wake-up times
V
DD
= 3.3 V; T
amb
= 25 °C
Power modes Wake-up time
Sleep mode (12 MHz)
[1][2]
2.6 s
Deep-sleep mode
[1][3]
4.4 s
Power-down mode
[1][3]
86.8 s
Deep Power-down mode
[4]
276 s