LPC5411x
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet
Rev. 2.1 — 9 May 2018
21 of 105
NXP Semiconductors
LPC5411x
32-bit ARM Cortex-M4/M0+ microcontroller
6.2.1 Termination of unused pins
shows how to terminate pins that are
not
used in the application. In many cases,
unused pins should be connected externally or configured correctly by software to
minimize the overall power consumption of the part.
Unused pins with GPIO function should be configured as outputs set to LOW with their
internal pull-up disabled. To configure a GPIO pin as output and drive it LOW, select the
GPIO function in the IOCON register, select output in the GPIO DIR register, and write a 0
to the GPIO PORT register for that pin. Disable the pull-up in the pin’s IOCON register.
In addition, it is recommended to configure all GPIO pins that are not bonded out on
smaller packages as outputs driven LOW with their internal pull-up disabled.
[1]
I = Input, IA = Inactive (no pull-up/pull-down enabled), PU = Pull-Up enabled, F = Floating
6.2.2 Pin states in different power modes
[1]
Default and programmed pin states are retained in sleep and deep-sleep modes.
Table 5.
Termination of unused pins
Pin
Default
state
Recommended termination of unused pins
RESET
I; PU
The RESET pin can be left unconnected if the application does not use it.
all PIOn_m (not open-drain) I; PU
Can be left unconnected if driven LOW and configured as GPIO output with pull-up
disabled by software.
PIOn_m (I2C open-drain)
IA
Can be left unconnected if driven LOW and configured as GPIO output by software.
USB_DP
F
If USB interface is not used, pin can be left unconnected except in deep
power-down mode where it must be externally pulled low.
USB_DM
F
If USB interface is not used, pin can be left unconnected except in deep
power-down mode where it must be externally pulled low.
RTCXIN
-
Connect to ground. When grounded, the RTC oscillator is disabled.
RTCXOUT
-
Can be left unconnected.
VREFP
-
Tie to V
DD
.
VREFN
-
Tie to V
SS
.
V
DDA
-
Tie to V
DD
.
V
SSA
-
Tie to V
SS
.
Table 6.
Pin states in different power modes
Pin
Active
Sleep
Deep-sleep
Deep power-down
PIOn_m pins (not I2C)
As configured in the IOCON
. Default: internal pull-up enabled. Floating.
PIO0_23 to PIO0_26 (open-drain
I2C-bus pins)
As configured in the IOCON
. Floating.
RESET
Reset function enabled. Default: input, internal pull-up enabled.