LPC1786FBD208,551 NXP Semiconductors, LPC1786FBD208,551 Datasheet - Page 63

• Manufacturer Part Number: LPC1786FBD208,551
• Description: Processors - Application Specialized CORTEX-M3 256KB FL 80KB SRAM 4KB EE USB
• Manufacturer: NXP Semiconductors
• Series: LPC17xxr

Specifications of LPC1786FBD208,551

• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 120MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, Microwire, MMC, SPI, SSI, SSP, UART/USART, USB OTG
• Peripherals: Brown-out Detect/Reset, DMA, I²S, LCD, Motor Control PWM, POR, PWM, WDT
• Number Of I /o: 165
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 80K x 8
• Voltage - Supply (vcc/vdd): 2.4 V ~ 3.6 V
• Data Converters: A/D 8x12b, D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 208-LQFP
• Lead Free Status / Rohs Status: Details
• Other names: 935291855551

NXP Semiconductors
LPC178X_7X
Objective data sheet
7.33.4.1 Sleep mode
7.33.3 Wake-up timer
7.33.4 Power control
The LPC178x/7x begin operation at power-up and when awakened from Power-down
mode by using the 12 MHz IRC oscillator as the clock source. This allows chip operation
to resume quickly. If the main oscillator or the PLL is needed by the application, software
will need to enable these features and wait for them to stabilize before they are used as a
clock source.
When the main oscillator is initially activated, the wake-up timer allows software to ensure
that the main oscillator is fully functional before the processor uses it as a clock source
and starts to execute instructions. This is important at power on, all types of reset, and
whenever any of the aforementioned functions are turned off for any reason. Since the
oscillator and other functions are turned off during Power-down mode, any wake-up of the
processor from Power-down mode makes use of the wake-up Timer.
The wake-up timer monitors the crystal oscillator to check whether it is safe to begin code
execution. When power is applied to the chip, or when some event caused the chip to exit
Power-down mode, some time is required for the oscillator to produce a signal of sufficient
amplitude to drive the clock logic. The amount of time depends on many factors, including
the rate of V
characteristics (if a quartz crystal is used), as well as any other external circuitry (e.g.,
capacitors), and the characteristics of the oscillator itself under the existing ambient
conditions.
The LPC178x/7x support a variety of power control features. There are four special
modes of processor power reduction: Sleep mode, Deep-sleep mode, Power-down mode,
and Deep power-down mode. The CPU clock rate may also be controlled as needed by
changing clock sources, reconfiguring PLL values, and/or altering the CPU clock divider
value. This allows a trade-off of power versus processing speed based on application
requirements. In addition, the peripheral power control allows shutting down the clocks to
individual on-chip peripherals, allowing fine tuning of power consumption by eliminating all
dynamic power use in any peripherals that are not required for the application. Each of the
peripherals has its own clock divider which provides even better power control.
Integrated PMU (Power Management Unit) automatically adjust internal regulators to
minimize power consumption during Sleep, Deep sleep, Power-down, and Deep
power-down modes.
The LPC178x/7x also implement a separate power domain to allow turning off power to
the bulk of the device while maintaining operation of the RTC and a small set of registers
for storing data during any of the power-down modes.
When Sleep mode is entered, the clock to the core is stopped. Resumption from the Sleep
mode does not need any special sequence other than re-enabling the clock to the ARM
core.
In Sleep mode, execution of instructions is suspended until either a Reset or interrupt
occurs. Peripheral functions continue operation during Sleep mode and may generate
interrupts to cause the processor to resume execution. Sleep mode eliminates dynamic
power used by the processor itself, memory systems and related controllers, and internal
buses.
DD(3V3)
All information provided in this document is subject to legal disclaimers.
ramp (in the case of power on), the type of crystal and its electrical
Rev. 2 — 27 May 2011
32-bit ARM Cortex-M3 microcontroller
LPC178x/7x
© NXP B.V. 2011. All rights reserved.
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