7.3 Feature Description

7.3.1 Analog Input

The high-impedance input stage of the AMC3336 feeds a second-order, switched-capacitor, feed-forward ΔΣ

modulator. The modulator converts the analog signal into a bitstream that is transferred over the isolation barrier,

as described in the Isolation Channel Signal Transmission section. The high-impedance, and low bias-current

input makes the AMC3336 suitable for isolated, high-voltage-sensing applications that typically employ high

impedance resistor dividers.

For reduced offset and offset drift, the input buffer is chopper-stabilized with the chopping frequency set at

clock of 20 MHz.

Frequency (kHz)

0.1

1

10

100

1000

10000

-160

-140

-120

-100

-80

-60

-40

-20

0

Figure 7-1. Quantization Noise Shaping

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

range specified in the Absolute Maximum Ratings table, the input current must be limited to 10 mA because the

device input electrostatic discharge (ESD) diodes turn on. Second, the linearity and noise performance of the

device are ensured only when the differential analog input voltage remains within the specified linear full-scale

Operating Conditions table.

AMC3336

SBASA70 – APRIL 2021

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