LPC11U13FBD48 NXP Semiconductors, LPC11U13FBD48 Datasheet - Page 25

• Manufacturer Part Number: LPC11U13FBD48
• Description: The LPC11U13FBD48 is a ARM Cortex-M0 based, low-cost 32-bit MCU, designed for 8/16-bit microcontroller applications, offering performance, low power, simple instruction set and memory addressing together with reduced code size compared to existing 8/
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC11U1X
Product data sheet
7.16.1.2 System oscillator
7.16.1.3 Watchdog oscillator
7.16.2 System PLL and USB PLL
7.16.3 Clock output
7.16.4 Wake-up process
7.16.5 Power control
The system oscillator can be used as the clock source for the CPU, with or without using
the PLL. On the LPC11U1x, the system oscillator must be used to provide the clock
source to USB.
The system oscillator operates at frequencies of 1 MHz to 25 MHz. This frequency can be
boosted to a higher frequency, up to the maximum CPU operating frequency, by the
system PLL.
The watchdog oscillator can be used as a clock source that directly drives the CPU, the
watchdog timer, or the CLKOUT pin. The watchdog oscillator nominal frequency is
programmable between 7.8 kHz and 1.7 MHz. The frequency spread over processing and
temperature is 40 % (see also
The LPC11U1x contain a system PLL and a dedicated PLL for generating the 48 MHz
USB clock. The system and USB PLLs are identical.
The PLL accepts an input clock frequency in the range of 10 MHz to 25 MHz. The input
frequency is multiplied up to a high frequency with a Current Controlled Oscillator (CCO).
The multiplier can be an integer value from 1 to 32. The CCO operates in the range of
156 MHz to 320 MHz, so there is an additional divider in the loop to keep the CCO within
its frequency range while the PLL is providing the desired output frequency. The output
divider may be set to divide by 2, 4, 8, or 16 to produce the output clock. The PLL output
frequency must be lower than 100 MHz. Since the minimum output divider value is 2, it is
insured that the PLL output has a 50 % duty cycle. The PLL is turned off and bypassed
following a chip reset and may be enabled by software. The program must configure and
activate the PLL, wait for the PLL to lock, and then connect to the PLL as a clock source.
The PLL settling time is 100 s.
The LPC11U1x features a clock output function that routes the IRC oscillator, the system
oscillator, the watchdog oscillator, or the main clock to an output pin.
The LPC11U1x begin operation at power-up and when awakened from Deep 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.
The LPC11U1x 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, a register is provided for shutting down the clocks to individual
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 11 January 2012
Table
13).
32-bit ARM Cortex-M0 microcontroller
LPC11U1x
© NXP B.V. 2012. All rights reserved.
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