7.3 Feature Description

7.3.1 Analog Input

The high-impedance input buffer on the INP pin feeds a second-order, switched-capacitor, feed-forward ΔΣ

modulator. The modulator converts the analog signal into a bitstream that is transferred across the isolation

barrier, as described in the Isolation Channel Signal Transmission section.

There are two restrictions on the analog input signal. First, if the input voltage exceeds the value specified

in the Absolute Maximum Ratings table, the input current must be limited to 10mA. This limitation is caused

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

are specified only when the input voltage is within the linear full-scale range (VFSR). VFSR is specified in the

Recommended Operating Conditions table.

7.3.2 Isolation Channel Signal Transmission

As shown in Figure 7-1, the AMC0x00D uses an on-off keying (OOK) modulation scheme to transmit the

modulator output bitstream across the SiO2-based isolation barrier. The transmit driver (TX) is illustrated in the

Functional Block Diagram . TX transmits an internally generated, high-frequency carrier across the isolation

barrier to represent a digital one. However, TX does not send a signal to represent a digital zero. The nominal

frequency of the carrier used inside the AMC0x00D is 480MHz.

The receiver (RX) on the other side of the isolation barrier recovers and demodulates the signal and provides

the input to the analog filter. The AMC0x00D transmission channel is optimized to achieve the highest level of

common-mode transient immunity (CMTI) and the lowest level of radiated emissions. The high-frequency carrier

and RX/TX buffer switching cause these emissions.

Modulator Bitstream

on High-side

Internal Clock

Signal Across Isolation Barrier

Recovered Sigal

on Low-side

Figure 7-1. OOK-Based Modulation Scheme

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AMC0200D, AMC0300D

SBASAR7A – SEPTEMBER 2025 – REVISED JUNE 2026

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