AMC1304L05_15 Datasheet, PDF (21/39 Pages) Texas Instruments – AMC1304x High-Precision,Reinforced Isolated Delta-Sigma Modulators with LDO

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AMC1304L05, AMC1304L25, AMC1304M05, AMC1304M25
SBAS655C – SEPTEMBER 2014 – REVISED SEPTEMBER 2015
Feature Description (continued)
8.3.3 Digital Output
A differential input signal of 0 V ideally produces a stream of ones and zeros that are high 50% of the time. A
differential input of 250 mV (for the AMC1304x25) or 50 mV (for the AMC1304x05) produces a stream of ones
and zeros that are high 90% of the time. A differential input of –250 mV (–50 mV for the AMC1304x05) produces
a stream of ones and zeros that are high 10% of the time. These input voltages are also the specified linear
ranges of the different AMC1304 versions with performance as specified in this data sheet. If the input voltage
value exceeds these ranges, the output of the modulator shows non-linear behavior when the quantization noise
increases. The output of the modulator clips with a stream of only zeros with an input less than or equal to
–312.5 mV (–62.5 mV for the AMC1304x05) or with a stream of only ones with an input greater than or equal to
312.5 mV (62.5 mV for the AMC1304x05). In this case, however, the AMC1304 generates a single 1 (if the input
is at negative full-scale) or 0 every 128 clock cycles to indicate proper device function (see the Fail-Safe Output
section for more details). The input voltage versus the output modulator signal is shown in Figure 47.
The density of ones in the output bit-stream for any input voltage value (with the exception of a full-scale input
signal, as described in the Output Behavior in Case of a Full-Scale Input section) can be calculated using
Equation 1:
V _IN
V _Clipping
2 * V _Clipping
(1)
The AMC1304 system clock is typically 20 MHz and is provided externally at the CLKIN pin. Data are
synchronously provided at 20 MHz at the DOUT pin. Data change at the CLKIN falling edge. For more details,
see the Switching Characteristics table.
Modulator Output
+FS (Analog Input)
-FS (Analog Input)
Analog Input
Figure 47. Analog Input versus AMC1304 Modulator Output
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