7.3.1 Insulation Characteristics

7.3.2 IEC 61000-4-5 Ratings

7.3.3 IEC 60664-1 Ratings⁽¹⁾

7.3.4 Package Characteristics⁽¹⁾

7.3.5 IEC Safety Limiting Values

Safety limiting intends to prevent potential damage to the isolation barrier upon failure of input or output (I/O) circuitry. A failure of the I/O circuitry can allow low resistance to ground or the supply and, without current limiting, dissipate sufficient power to overheat the die and damage the isolation barrier, potentially leading to secondary system failures.

The safety-limiting constraint is the operating virtual junction temperature range specified in the Absolute Maximum Ratings table. The power dissipation and junction-to-air thermal impedance of the device installed in the application hardware determine the junction temperature. The assumed junction-to-air thermal resistance in the Thermal Information table is that of a device installed in the JESD51-3, Low Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages and is conservative. The power is the recommended maximum input voltage times the current. The junction temperature is then the ambient temperature plus the power times the junction-to-air thermal resistance.

7.3.6 Regulatory Information

7.3.7 Isolation Amplifier

The AMC1200 device consists of a second order delta-sigma modulator input stage including an internal reference and clock generator. The output of the modulator and clock signal are differentially transmitted over the integrated capacitive isolation barrier that separates the high- and low-voltage domains. The received bitstream and clock signals are synchronized and processed by a third-order analog filter with a nominal gain of 8 on the low-side and presented as a differential output of the device, as shown in Functional Block Diagram section.

7.3.8 Analog Input

The analog input range is tailored to directly accommodate a voltage drop across a shunt resistor used for current sensing. However, there are two restrictions on the analog input signals, VINP and VINN. If the input voltage exceeds the range AGND – 0.5 V to AVDD + 0.5 V, the input current must be limited to 10 mA to prevent the implemented input protection diodes from damage. In addition, the linearity and the noise performance of the device are ensured only when the differential analog input voltage remains within ±250 mV.

The differential analog input of the AMC1200 and AMC1200B devices is a switched-capacitor circuit based on a second-order modulator stage that digitizes the input signal into a 1-bit output stream. These devices compare the differential input signal (V_IN = VINP – VINN) against the internal reference of 2.5 V using internal capacitors that are continuously charged and discharged with a typical frequency of 10 MHz. With the S1 switches closed, C_IND charges to the voltage difference across VINP and VINN. For the discharge phase, both S1 switches open first and then both S2 switches close. C_IND discharges to approximately AGND + 0.8 V during this phase. Figure 31 shows the simplified equivalent input circuitry.

Figure 31. Equivalent Input Circuit