AMC3306M25 datasheet(13/29 Pages) TI1

13 / 29 page

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AMC3306M25

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7.3 Feature Description

7.3.1 Analog Input

The AMC3306M25 incorporates front-end circuitry that contains a differential amplifier and a sampling stage,

followed by a ΔΣ modulator. The gain of the differential amplifier is set by internal precision resistors to a factor of

4, resulting in a differential input impedance of RIND, as specified in the Electrical Characteristics table. For

reduced offset and offset drift, the differential amplifier is chopper-stabilized with the chopping frequency set at

fCLKIN / 32. Figure 6 shows the spur that is generated by the switching frequency.

sinc3 filter, OSR = 2, fCLKIN = 20 MHz, fIN = 1 kHz

Figure 6. Quantization Noise Shaping

There are two restrictions on the analog input signals (INP and INN). First, if the input voltage exceeds the range

HGND – 6 V to VHLDO_OUT + 0.5 V, the input current must be limited to 10 mA because the device input

electrostatic discharge (ESD) diodes turn on. In addition, the linearity and noise performance of the device are

ensured only when the differential analog input voltage remains within the specified linear full-scale range (FSR)

of ±250 mV, and within the specified input common-mode voltage range.

AMC3306M25 데이터시트(PDF) 13 Page - Texas Instruments