AMC1306E05 Datasheet, PDF (22/40 Pages) Texas Instruments – Small, High-Precision, Reinforced Isolated Delta-Sigma Modulators with High CMTI

AMC1306E05, AMC1306E25, AMC1306M05, AMC1306M25
SBAS734 – MARCH 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 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 AMC1306 implements a fail-safe output function that ensures that the output DOUT of the device
offers a steady-state bitstream of logic 0's in case of a missing AVDD, as shown in Figure 48.
Additionally, 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 AMC1306 offers a steady-
state bitstream of logic 1's at the output DOUT, as also shown in Figure 48.
tISTART
tASTART
CLKIN
...
AVDD
AVDD GOOD
Missing AVDD
AVDD GOOD
VCM
VCM < VCMov
VCM • 9CMov
VCM < VCMov
DOUT Valid Bit Stream 1
0
Test Pattern
1
Bit Stream Not Valid Valid Bit Stream
Figure 48. Fail-Safe Output of the AMC1306
8.4.2 Output Behavior in Case of a Full-Scale Input
If a full-scale input signal is applied to the AMC1306 (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 AVDD and a full-scale input signal is possible on the system level.
CLKIN
DOUT
DOUT
...
...
VIN ” ±320 mV (AMC1306x05: ±64 mV)
...
...
...
...
VIN • 320 mV (AMC1306x05: 64 mV)
127 CLKIN Cycles
127 CLKIN Cycles
Figure 49. Overrange Output of the AMC1306
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