AMC1303E0510 Datasheet, PDF (22/40 Pages) Texas Instruments – Small, High-Precision, Reinforced Isolated Delta-Sigma Modulators with Internal Clock

AMC1303E0510, AMC1303M0510, AMC1303E0520, AMC1303M0520
AMC1303E2510, AMC1303M2510, AMC1303E2520, AMC1303M2520
SBAS771 – JUNE 2017
www.ti.com
8.4 Device Functional Modes
8.4.1 Fail-Safe Output
In the case of a missing high-side supply voltage AVDD, the output of the ΔΣ modulator is not defined and can
cause a system malfunction. In systems with high safety requirements, this behavior is not acceptable.
Therefore, as shown in Figure 2, the AMC1303 implements a fail-safe output function that pulls the DOUT and
CLKOUT outputs (AMC1303Mx only) to a steady-state logic 1 in case of a missing AVDD.
Similarly, as also shown in Figure 43, if the common-mode voltage of the input reaches or exceeds the specified
common-mode overvoltage detection level V_CMov as defined in the Electrical Characteristics table, the AMC1303
generates a steady-state bitstream of logic 1's at the DOUT output.
In both cases, the steady-state logic 1 occurs on the DOUT output with a delay of two clock cycles after the
event of either exceeded common-mode input voltage or missing AVDD. Another 256 clock cycles are required
for the CLKOUT pin of the AMC1303Mx to be held at logic 1.
VCM
VCM < VCMov
VCM • 9CMov
VCM < VCMov
CLKOUT
(AMC1303Mx only)
4 cycles
256 cycles
...
µ1¶
4 cycles
DOUT
Valid bitstream
µ1¶
Valid bitstream
Figure 43. Fail-Safe Output of the AMC1303
8.4.2 Output Behavior in Case of a Full-Scale Input
If a full-scale input signal is applied to the AMC1303 (that is, |V_IN| ≥ |V_Clipping|), Figure 44 shows that the device
generates a single one or zero every 128 bits at DOUT, depending on the actual polarity of the signal being
sensed. In this way, differentiating between a missing AVDD and a full-scale input signal is possible on the
system level.
CLKOUT
(AMC1303Mx only)
DOUT
DOUT
...
...
VIN ” -320 mV (AMC1303x05x: ” -64 mV)
...
...
...
...
VIN • 320 mV (AMC1303x05x: H 64 mV)
127 CLK cycles
127 CLK cycles
Figure 44. Overrange Output of the AMC1303
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