lpc1778 NXP Semiconductors, lpc1778 Datasheet - Page 68

• Manufacturer Part Number: lpc1778
• Description: 32-bit Arm Cortex-m3 Microcontroller; Up To 512 Kb Flash And 96 Kb Sram; Usb Device/host/otg; Ethernet; Lcd; Emc
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC178x_7x
Objective data sheet
7.32.7 Power domains
The LPC178x/7x provide two independent power domains that allow the bulk of the
device to have power removed while maintaining operation of the RTC and the backup
Registers.
On the LPC178x/7x, I/O pads are powered by the 3.3 V (V
V
CPU and most of the peripherals.
Depending on the LPC178x/7x application, a design can use two power options to
manage power consumption.
The first option assumes that power consumption is not a concern and the design ties the
V
supply for both pads, the CPU, and peripherals. While this solution is simple, it does not
support powering down the I/O pad ring “on the fly” while keeping the CPU and
peripherals alive.
The second option uses two power supplies; a 3.3 V supply for the I/O pads (V
a dedicated 3.3 V supply for the CPU (V
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
there is no power drain from the RTC battery when V
DD(REG)(3V3)
DD(3V3)
DD(REG)(3V3)
and V
pin powers the on-chip voltage regulator which in turn provides power to the
) is used to operate the RTC whenever V
DD(REG)(3V3)
All information provided in this document is subject to legal disclaimers.
Rev. 00.04 — 8 July 2010
pins together. This approach requires only one 3.3 V power
DD(REG)(3V3)
32-bit ARM Cortex-M3 microcontroller
). Having the on-chip voltage regulator
DD(REG)(3V3)
DD(REG)(3V3)
DD(3V3)
LPC178x/7x
) pins, while the
is available.
is present. Therefore,
© NXP B.V. 2010. All rights reserved.
DD(3V3)
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) and