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FDC2214: FDC2214 output rate

Part Number: FDC2214

您好,请问除了以下3个寄存器可以修改采样速率之外,还有其他的吗?

SETTLECOUNT_CHx
RCOUNT_CHx
CLOCK_DIVIDERS_CHx

目前通过这三个寄存器值的修改,可以实现100sps的采样速率,是否有其他寄存器可以调节速率,怎样能实现单通道1ksps的极值?

谢谢!!

  • 您好,

    FDC2214 采样阶段包括3部分:1. sensor activation time 2. conversion time 3. channel switch delay

    转换过程每个阶段时间加起来,得到的这个时间的倒数,即是采样速率

    看datasheet figure13和figure14,如果要工作在最快采样速率时,就需要工作在单通道连续转换模式下;

    因此 settling wait time计算公式:

    tSx = (CHX_SETTLECOUNTˣ16)/fREFx

    The SETTLECOUNT for any channel x must satisfy:

    CHx_SETTLECOUNT > Vpk × fREFx × C × π 2 / (32 × IDRIVEX)

    where

    • Vpk = Peak oscillation amplitude at the programmed IDRIVE setting

    • fREFx = Reference frequency for Channel x

    • C = sensor capacitance including parasitic PCB capacitance

    • IDRIVEX = setting programmed into the IDRIVE register in amps

    同时 conversion time计算公式:

    tCx = (CHx_RCOUNT ˣ 16 + 4) /fREFx

    因此还与reference frequency有关;

  • Amy 您好,感谢您的回复。

    reference frequency 是通过CLOCK_DIVIDERS_CHx寄存器调节的对吗?

    除了之前提到的三个寄存器

    SETTLECOUNT_CHx
    RCOUNT_CHx
    CLOCK_DIVIDERS_CHx

    是否还有其他的寄存器对提升采样速率有影响?谢谢啊~

  • 是的,通过REF_CLK_SRC选择时钟源;

    还有与传感器电流驱动有关的寄存器,如 datasheet Table 9中列出的 Current Drive Control Registers

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