AMC1304L05_15 Datasheet, PDF (22/39 Pages) Texas Instruments – AMC1304x High-Precision,Reinforced Isolated Delta-Sigma Modulators with LDO

AMC1304L05, AMC1304L25, AMC1304M05, AMC1304M25
SBAS655C – SEPTEMBER 2014 – REVISED SEPTEMBER 2015
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8.4 Device Functional Modes
8.4.1 Fail-Safe Output
In the case of a missing high-side supply voltage (LDOIN), the output of a ΔΣ modulator is not defined and can
cause a system malfunction. In systems with high safety requirements, this behavior is not acceptable.
Therefore, the AMC1304 implements a fail-safe output function that ensures the device maintains its output level
in case of a missing LDOIN, as shown in Figure 48.
CLKIN
LDOIN
LDOIN GOOD
LDOIN FAIL
DOUT
DOUT
Figure 48. Fail-Safe Output of the AMC1304
8.4.2 Output Behavior in Case of a Full-Scale Input
If a full-scale input signal is applied to the AMC1304 (that is, V_IN ≥ V_Clipping), the device generates a single one or
zero every 128 bits at DOUT, depending on the actual polarity of the signal being sensed, as shown in Figure 49.
In this way, differentiating between a missing LDOIN and a full-scale input signal is possible on the system level.
CLKIN
DOUT
DOUT
...
...
VIN ” -312.5 mV (AMC1304x05: -61.5 mV)
...
...
...
...
VIN • 312.5 mV (AMC1304x05: 61.5 mV)
127 CLKIN cycles
127 CLKIN cycles
Figure 49. Overrange Output of the AMC1304
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