lpc1756 NXP Semiconductors, lpc1756 Datasheet - Page 33

• Manufacturer Part Number: lpc1756
• Description: 32-bit Arm Cortex-m3 Mcu Up To 512 Kb Flash And 64 Kb Sram With Ethernet, Usb 2.0 Host/device/otg, Can
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC1758_56_54_52_51_2
Objective data sheet
7.29.8 Power domains
The LPC1758/56/54/52/51 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 LPC1758/56/54/52/51, I/O pads are powered by the 3.3 V (V
the V
the CPU and most of the peripherals.
Depending on the LPC1758/56/54/52/51 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(3V3)
DD(REG)(3V3)
DD(REG)(3V3)
and V
) is used to operate the RTC whenever V
DD(REG)(3V3)
pin powers the on-chip voltage regulator which in turn provides power to
Rev. 02 — 11 February 2009
pins together. This approach requires only one 3.3 V power
DD(REG)(3V3)
LPC1758/56/54/52/51
32-bit ARM Cortex-M3 microcontroller
). Having the on-chip voltage regulator
DD(REG)(3V3)
DD(REG)(3V3)
is available.
is present. Therefore,
DD(3V3)
© NXP B.V. 2009. All rights reserved.
) pins, while
DD(3V3)
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) and