Datasheet

LPC408X_7X All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 3.1 — 1 September 2014 77 of 138
NXP Semiconductors
LPC408x/7x
32-bit ARM Cortex-M4 microcontroller
The second option uses two power supplies; a 3.3 V supply for the I/O pads (V
DD(3V3)
) and
a dedicated 3.3 V supply for the CPU (V
DD(REG)(3V3)
). Having the on-chip voltage regulator
powered independently from the I/O pad ring enables shutting down of the I/O pad power
supply “on the fly” while the CPU and peripherals stay active.
The VBAT pin supplies power only to the RTC domain. The RTC requires a minimum of
power to operate, which can be supplied by an external battery. The device core power
(V
DD(REG)(3V3)
) is used to operate the RTC whenever V
DD(REG)(3V3)
is present. There is no
power drain from the RTC battery when V
DD(REG)(3V3)
is available and V
DD(REG)(3V3)
>
V
BAT
.
Fig 11. Power distribution
REAL-TIME CLOCK
BACKUP REGISTERS
REGULATOR
32 kHz
OSCILLATOR
POWER
SELECTOR
ULTRA-LOW
POWER
REGULATOR
RTC POWER DOMAIN
MAIN POWER DOMAIN
002aag738
RTCX1
VBAT
(typical 3.0 V)
V
DD(REG)(3V3)
(typical 3.3 V)
RTCX2
V
DD(3V3)
V
SS
to memories,
peripherals,
oscillators,
PLLs
to core
to I/O pads
ADC
DAC
ADC POWER DOMAIN
V
DDA
VREFP
V
SSA
LPC408x/7x