Broadcom ACPL-C799 User Manual

ACPL-C799 Evaluation Kit Board
Isloated Sigma-Delta Modulator
User Guide
Description
The Avago ACPL-C799 isolated sigma-delta (–) modulator converts an analog input signal into a high-speed (10 MHz typical)
single-bit data stream by means of a sigma-delta over-sampling modulator. The time average of the modulator data is directly
proportional to the input signal voltage. The modulator uses internal speed of 10 MHz. The modulator data are encoded and
transmitted across the isolation boundary where they are recovered and decoded into high-speed data stream of digital ones and
zeros. The original signal information is represented by the density of ones in the data output.
The input signal information is contained in the modulator output data stream, represented by the density of ones and zeros. The
density of ones is proportional to the input signal voltage, as shown in
data stream of ones 50 percent of the time and zeros 50 percent of the time. A differential input of –50 mV corresponds to 18.75
percent density of ones, and a differential input of +50 mV is represented by 81.25 percent density of ones in the data stream. A
differential input of +80 mV or higher results in ideally all ones in the data stream, while input of –80 mV or lower will result in all
zeros ideally. Table 1 shows this relationship.
Figure 1 Modulator Output vs. Analog Input
This User Guide is provided to assist you in the evaluation of product(s) currently under development. Until Broadcom releases this
product for general sales, Broadcom reserves the right to alter prices, specifications, features, capabilities, functions, release dates, and
remove availability of the product(s) at anytime
Figure 1. A differential input signal of 0 V ideally produces a
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