Datasheet

Product data sheet Rev. 1.2 — 21 May 2014 76 of 89

NXP Semiconductors

LPC11E6x

32-bit ARM Cortex-M0+ microcontroller

14.7 Termination of unused pins

Table 28 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, O = Output, IA = Inactive (no pull-up/pull-down enabled), F = floating, PU = Pull-Up.

Table 28. Termination of unused pins

Pin Default

state

[1]

Recommended termination of unused pins

RESET

/PIO0_0 I; PU In an application that does not use the RESET pin or its GPIO function, the

termination of this pin depends on whether Deep power-down mode is used:

• Deep power-down used: Connect an external pull-up resistor and keep pin in

default state (input, pull-up enabled) during all other power modes.

• Deep power-down not used and no external pull-up connected: can be left

unconnected if internal pull-up is disabled and pin is driven LOW and

configured as output by software.

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.

RSTOUT

IA; O Can be left unconnected. Not configurable by software.

RTCXIN - Connect to ground. When grounded, the RTC oscillator is disabled.

RTCXOUT - Can be left unconnected.

VREFP - Tie to VDD.

VREFN - Tie to VSS.

VDDA - Tie to VDD.

VBAT - Tie to VDD if no external battery connected.

VSSA - Tie to VSS.