MSP430F6638 Datasheet, PDF (66/126 Pages) Texas Instruments – Mixed-Signal Microcontrollers

MSP430F6638, MSP430F6637, MSP430F6636, MSP430F6635
MSP430F6634, MSP430F6633, MSP430F6632, MSP430F6631, MSP430F6630
SLAS566E – JUNE 2010 – REVISED DECEMBER 2015
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6.12.3 Oscillator and System Clock (Link to User's Guide)
The clock system is supported by the Unified Clock System (UCS) module that includes support for a 32-
kHz watch crystal oscillator (in XT1 LF mode; XT1 HF mode is not supported), an internal very-low-power
low-frequency oscillator (VLO), an internal trimmed low-frequency oscillator (REFO), an integrated internal
digitally controlled oscillator (DCO), and a high-frequency crystal oscillator XT2. The UCS module is
designed to meet the requirements of both low system cost and low power consumption. The UCS module
features digital frequency locked loop (FLL) hardware that, in conjunction with a digital modulator,
stabilizes the DCO frequency to a programmable multiple of the watch crystal frequency. The internal
DCO provides a fast turnon clock source and stabilizes in 3 µs (typical). The UCS module provides the
following clock signals:
• Auxiliary clock (ACLK), sourced from a 32-kHz watch crystal (XT1), a high-frequency crystal (XT2), the
internal low-frequency oscillator (VLO), the trimmed low-frequency oscillator (REFO), or the internal
digitally-controlled oscillator DCO.
• Main clock (MCLK), the system clock used by the CPU. MCLK can be sourced by same sources
available to ACLK.
• Sub-Main clock (SMCLK), the subsystem clock used by the peripheral modules. SMCLK can be
sourced by same sources available to ACLK.
• ACLK/n, the buffered output of ACLK, ACLK/2, ACLK/4, ACLK/8, ACLK/16, ACLK/32.
6.12.4 Power-Management Module (PMM) (Link to User's Guide)
The PMM includes an integrated voltage regulator that supplies the core voltage to the device and
contains programmable output levels to provide for power optimization. The PMM also includes supply
voltage supervisor (SVS) and supply voltage monitoring (SVM) circuitry, as well as brownout protection.
The brownout circuit is implemented to provide the proper internal reset signal to the device during power-
on and power-off. The SVS and SVM circuitry detects if the supply voltage drops below a user-selectable
level and supports both supply voltage supervision (the device is automatically reset) and supply voltage
monitoring (the device is not automatically reset). SVS and SVM circuitry is available on the primary
supply and core supply.
6.12.5 Hardware Multiplier (MPY) (Link to User's Guide)
The multiplication operation is supported by a dedicated peripheral module. The module performs
operations with 32-, 24-, 16-, and 8-bit operands. The module supports signed and unsigned multiplication
as well as signed and unsigned multiply-and-accumulate operations.
6.12.6 Real-Time Clock (RTC_B) (Link to User's Guide)
The RTC_B module can be configured for real-time clock (RTC) or calendar mode providing seconds,
minutes, hours, day of week, day of month, month, and year. Calendar mode integrates an internal
calendar which compensates for months with less than 31 days and includes leap year correction. The
RTC_B also supports flexible alarm functions and offset-calibration hardware. The implementation on this
device supports operation in LPM3.5 mode and operation from a backup supply.
The application report Using the MSP430 RTC_B Module With Battery Backup Supply (SLAA665)
describes how to use the RTC_B with battery backup supply functionality to retain the time and keep the
RTC counting through loss of main power supply, and how to perform correct reinitialization when the
main power supply is restored.
6.12.7 Watchdog Timer (WDT_A) (Link to User's Guide)
The primary function of the WDT_A module is to perform a controlled system restart after a software
problem occurs. If the selected time interval expires, a system reset is generated. If the watchdog function
is not needed in an application, the module can be configured as an interval timer and can generate
interrupts at selected time intervals.
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Detailed Description
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MSP430F6632 MSP430F6631 MSP430F6630