The Smart Timing Choice™ 1 SiT-AN10037 Rev 1.3
Optimized SiT15xx Drive Settings for
32 kHz Crystal Inputs of Low Power MCUs
Table of Contents
1Introduction ............................................................................................................................................2
2MCU 32 kHz Oscillator Operating Modes..............................................................................................2
3SiT15xx Output Drive Levels .................................................................................................................4
3.1 NanoDrive Reduced Swing Mode.................................................................................................4
3.2 Full-Swing LVCMOS Drive............................................................................................................5
4Energy Micro EFM32.............................................................................................................................6
5STMicroelectronics STM32....................................................................................................................6
6Renesas Electronics RL78G13..............................................................................................................7
7Texas Instruments MSP430F2x ............................................................................................................7
8NXP LPC11xx........................................................................................................................................8
9Freescale Kinetis L4x/L5x......................................................................................................................8
10 Appendix A: Programming the EnergyMicro EFM32 LFXO..............................................................9
10.1 EFM32 Clock Management Unit...................................................................................................9
10.2 Configuring the LFXO .................................................................................................................12
11 Appendix B: Programming the STMicroelectronics STM32 LSE Oscillator....................................13
11.1 Low-speed External Clock Oscillator ..........................................................................................13
11.2 External Clock Source (LSE bypass)..........................................................................................14
11.3 Clock Security System on LSE ...................................................................................................14
11.4 Clock-out Capability ....................................................................................................................14
11.5 Configuring LSE..........................................................................................................................15
12 Appendix C: Programming the Renesas Electronics RL78G13 XT1 Oscillator..............................16
12.1 XT1 Oscillator..............................................................................................................................16
12.2 Configuration XT1 .......................................................................................................................16
13 Appendix D: Programming the Texas Instruments MSP430 Low Frequency Oscillator ................18
13.1 The MSP430 LFXT Oscillator .....................................................................................................18
13.2 Clock-out Capability ....................................................................................................................20
13.3 Low-power Modes.......................................................................................................................20
14 Appendix E: Programming the NXP LPC1100 RTC Oscillator.......................................................21
14.1 Configuring of the RTC Oscillator ...............................................................................................21
14.2 Clock Output Capability...............................................................................................................21
15 Appendix F: Programming the Freescale Kinetis L4x and L5x System Oscillator..........................28
15.1 Programming Model....................................................................................................................28
15.2 Clock Output Capability...............................................................................................................34
