SLAA423A December   2009  – November 2018 MSP430F4132 , MSP430F4152 , MSP430F47126 , MSP430F47127 , MSP430F47163 , MSP430F47166 , MSP430F47167 , MSP430F47173 , MSP430F47176 , MSP430F47177 , MSP430F47183 , MSP430F47186 , MSP430F47187 , MSP430F47193 , MSP430F47196 , MSP430FG4616 , MSP430FG4617 , MSP430FG4618

 

  1.   XOSC8 Guidance
    1.     Trademarks
    2. 1 Introduction
    3. 2 Contribution of ESR, Load Capacitance, VCC, and Temperature
      1. 2.1 Crystal ESR
        1. 2.1.1 ESR and Start-up Reliability
        2. 2.1.2 ESR Specification
      2. 2.2 Load Capacitance
      3. 2.3 Temperature and VCC
    4. 3 Using a Shunt Resistor From XIN to GND
    5. 4 Failsafe Mechanisms
      1. 4.1 2xx Family
      2. 4.2 4xx Family
    6. 5 Summary
    7. 6 References
  2.   Revision History

3 Using a Shunt Resistor From XIN to GND

An alternative to increasing the ESR or load capacitance to increase the power output of the oscillator is to apply a shunt resistance between the oscillator input pin (XIN) and ground (AVSS). Retesting crystal 1a (ESR = 14 kΩ) with a load capacitance of 6 pF, the failure rate was improved to 0% with the addition of a 750-kΩ shunt resistor. The addition of the shunt resistance had very little impact and the safety factor was still "very safe" (greater than 5).

Generally, the impedance of the shunt resistance should increase with the ESR of the crystal until the crystal exceeds 40 kΩ, at which point the shunt resistance should be removed (infinite impedance).