Design and selection of MSP430 microcontroller peripheral crystal oscillator and precautions

火辣西米秀

Design and selection of MSP430 microcontroller peripheral crystal oscillator and precautions [Copy link]

The MSP430 series of microcontrollers is a 16-bit ultra-low MSP430 microcontroller that Texas Instruments (TI) began to market in 1996. It has low power consumption and is a mixed signal processor with a reduced instruction set (RISC). It is called a mixed signal processor because it integrates multiple analog circuits, digital circuit modules and microprocessors with different functions on one chip to provide a "single-chip" solution for practical application needs.
This series of microcontrollers is mostly used in portable instruments that require battery power. This article mainly explains the design selection and precautions of the MSP430 series chip peripheral crystal oscillator.
---MSP430F149
The MSP430 series chip generally has two external crystal oscillators: one main frequency crystal oscillator, usually selected from 4~16Mhz; the other clock crystal oscillator, that is, a 32.768Khz crystal oscillator, was selected in the early days of direct plug-in packaging, and now most of the products use chip packaging, one is easy to mount, and the other is the pursuit of product stability and quality reliability.
---Application Circuit
---MSP430 Development Board
1. Selection of main frequency crystal oscillator
The main frequency crystal oscillator of the MSP430 chip is usually selected as an integer multiple of 4Mhz, i.e. 4Mhz, 8Mhz, 16Mhz, 32Mhz, etc. In the early circuit design, the low-cost 49S package products were generally selected. At this stage, more and more people tend to prefer the patch 3225 package products with better stability, smaller size and easy mounting. Shanghai Tanghui Electronics** launched the DSX321G and DSX320G\DSX320GE products launched by Japan KDS Vacuum Company.
1. DSX321G 8Mhz for industrial and consumer products, as shown in the figure below:

The package of this model is 3.2mm*2.5mm, the volume is less than 1/5 of the traditional direct-insert 49S package, the accuracy can reach 20PPM, and the operating temperature reaches the industrial level of -40—+85°C, which can fully meet the requirements of customers.

2. DSX320G/DSX320GE is used for automotive electronics and industrial control products, as shown in the figure below:
The package of this model agrees to be 3.2*2.5mm, and the accuracy can reach 100ppm and 50ppm. In addition to the temperature that can meet the customer's requirements of -40-+125°C and -40-+150°C, it also meets the AEC-Q200 standard.
2. Selection of 32.768Khz clock crystal
There are many models in the 32.768Khz family, various direct plug-in and surface mount, various load capacitors, and various precisions.根据MSP430不同的系列做一下针对性的推荐：
IC name Quartz crystal CL(pF)
MSP430F169 32.768kHz 12.5
MSP430F2131 32.768kHz 12.5
MSP430F2131 32.768kHz 6
MSP430F413 32.768kHz 12.5
MSP430F413 32.768kHz 6
MSP430FG4619 32.768kHz 12.5
MSP430FG4619 32.768kHz 6
MSP430F1232IPW 32.768kHz 12.5
MSP430F1XX 32.768kHz 12.5
MSP430F2XX 32.768kHz 12.5
MSP430F4XX 32.768kHz 12.5
MSP430F4XX 32.768kHz 12.5
MSP430F5XX 32.768kHz 12.5
MSP430FE427 32.768kHz 6
MSP430P325 32.768kHz 6
1. Low load, low ESR value products:
Direct plug package DT-26 32.768Khz 20PPM 6PF SMD

package DMX-26S 32.768Khz 20PPM 6PF SMD

package NX3215SA 32.768Khz 20PPM 6PF

2. Conventional load products:
Direct plug package DT-26 32.768Khz 20PPM 12.5PF
SMD package DMX-26S 32.768Khz 20PPM 12.5PF
SMD package NX3215SA 32.768Khz 20PPM 12.5PF
32.768Khz crystal oscillator, please find Shanghai Tanghui Electronics, daily spot, original authentic.
Shanghai Tanghui Electronics, deeply involved in the crystal oscillator industry for 15 years, very professional, industry recognized!
KDS, NDK, EPSON, SEIKO, SITIME. Monthly throughput up to 100 million!
8M, 16M, 24M, 32M are often in stock!
The following article is very important, many R&D engineers are troubled here. The principle, basic application, and precautions for the use of
the 32.768Khz crystal oscillator (taking the cylindrical crystal oscillator as an example) with the MSP430 microcontroller . Precautions for the use of the tuning fork type crystal oscillator standard (32.768Khz cylindrical crystal oscillator) 1. Impact resistance After applying excessive impact, it will cause the characteristics to deteriorate or not vibrate. Pay full attention not to drop it. In addition, use it under non-impact conditions as much as possible. When automatically soldering or changing conditions, fully confirm before use. 2. Heat resistance and humidity resistance Long-term use and storage under high or low temperature or high humidity conditions will cause the vibrator to deteriorate. Use and store it under normal temperature and humidity conditions as much as possible. 3. Solder heat resistance Standard vibrators use solder with a melting point of 178℃. If the temperature inside the vibrator exceeds 150℃, it will cause the product characteristics to deteriorate or not vibrate. When assembling under conditions exceeding the above temperature, whether to use heat-resistant products or SMD vibrators.











When using flow solder for welding, please fully confirm or contact us.
Welding conditions, lead part, 280℃ or less within 5 seconds or 260℃ or less than 10 seconds.
Also, please do not directly weld at the root of the lead. This causes the characteristics to deteriorate.
4. Printed circuit board assembly method
When the tuning fork type vibrator is placed sideways, please fully fix it to the circuit board. Especially for the vibrating part, put a buffer material between the circuit board and the vibrator as shown in the figure, or fix it with an adhesive with good elasticity (silicone, etc.). In addition, please avoid applying adhesive to the base glass part.
When the vibrator is used upright, the distance between the vibrator and the circuit board is more than 3mm for DT-38 type and more than 2mm for DT-26 type.
5. Lead processing
When cutting the lead, the cutting knife should be fully prepared.
When processing the lead or correcting the lead bending, applying too much force to the root of the lead will cause the base glass to crack, etc., or applying too much force to the press-fit part will cause poor air leakage. In addition, a straight lead portion of more than 0.5mm should be left at the root of the lead.
6. Ultrasonic cleaning and ultrasonic soldering
Since the internal crystal plate resonates and causes no oscillation, we cannot guarantee whether ultrasonic soldering can be performed.
Regarding ultrasonic cleaning, please confirm with your company.
7. Excitation standard
If the vibrator is used at an excessively large excitation standard, the characteristics will deteriorate or no oscillation will occur.
For this type of vibrator, our company recommends using it below 1.0μW. It is not guaranteed to be used above 2.0μW.