LPC2470 NXP Semiconductors, LPC2470 Datasheet - Page 45

• Manufacturer Part Number: LPC2470
• Description: NXP Semiconductors designed the LPC2470 microcontroller, powered by theARM7TDMI-S core, to be a highly integrated microcontroller for a wide range ofapplications that require advanced communications and high quality graphic displays
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC2470
Product data sheet
7.25.4.4 Deep power-down mode
7.25.4.5 Power domains
7.26.1 Reset
7.26 System control
Deep power-down mode is similar to the Power-down mode, but now the on-chip
regulator that supplies power to the internal logic is also shut off. This produces the lowest
possible power consumption without removing power from the entire chip. Since the Deep
power-down mode shuts down the on-chip logic power supply, there is no register or
memory retention, and resumption of operation involves the same activities as a full chip
reset.
If power is supplied to the LPC2470 during Deep power-down mode, wake-up can be
caused by the RTC Alarm interrupt or by external Reset.
While in Deep power-down mode, external device power may be removed. In this case,
the LPC2470 will start up when external power is restored.
Essential data may be retained through Deep power-down mode (or through complete
powering off of the chip) by storing data in the Battery RAM, as long as the external power
to the VBAT pin is maintained.
The LPC2470 provides two independent power domains that allow the bulk of the device
to have power removed while maintaining operation of the RTC and the Battery RAM.
On the LPC2470, I/O pads are powered by the 3.3 V (V
V
the CPU and most of the peripherals.
Although both the I/O pad ring and the core require a 3.3 V supply, different powering
schemes can be used depending on the actual application requirements.
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
converter 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 and the Battery RAM. These two functions
require a minimum of power to operate, which can be supplied by an external battery.
When the CPU and the rest of chip functions are stopped and power removed, the RTC
can supply an alarm output that may be used by external hardware to restore chip power
and resume operation.
Reset has four sources on the LPC2470: the RESET pin, the Watchdog reset, power-on
reset, and the BrownOut Detection (BOD) circuit. The RESET pin is a Schmitt trigger input
pin. Assertion of chip Reset by any source, once the operating voltage attains a usable
DD(DCDC)(3V3)
DD(3V3)
and V
pins power the on-chip DC-to-DC converter which in turn provides power to
DD(DCDC)(3V3)
All information provided in this document is subject to legal disclaimers.
Rev. 4 — 8 September 2011
pins together. This approach requires only one 3.3 V power
DD(DCDC)(3V3)
Flashless 16-bit/32-bit microcontroller
). Having the on-chip DC-DC
DD(3V3)
) pins, while the
LPC2470
© NXP B.V. 2011. All rights reserved.
DD(3V3)
45 of 91
) and