SBASA51 May 2020 AMC1336-Q1
PRODUCTION DATA.
Use Ohm's Law to calculate the minimum total resistance of the resistive dividers to limit the cross current to the desired values:
Consider the following two restrictions to choose the proper value of the resistors RDC3 and RAC3:
Use similar approach for calculation of the shunt resistor values RSHUNT and see the AMC1305M05-Q1 for further details.
Table 12 lists examples of nominal E96-series (1% accuracy) resistor values for systems using 600 V and 800 V on the DC bus.
| PARAMETER | 600-V DC BUS | 800-V DC BUS | |
|---|---|---|---|
| Resistive divider resistor RDC1 | 3.01 MΩ | 4.22 MΩ | |
| Resistive divider resistor RDC2 | 3.01 MΩ | 4.22 MΩ | |
| Sense resistor RDC3 | 10 kΩ | 10.5 kΩ | |
| Resulting current through resistive divider IDC | 99.5 µA | 94.7 µA | |
| Resulting voltage drop on sense resistor VRDC3 | 0.995 V | 0.994 V | |
Table 13 lists examples of nominal E96-series (1% accuracy) resistor values for systems using 230 V and 690 V on the input or output phases.
| PARAMETER | ±400-VAC PHASE | ±690-VAC PHASE | |
|---|---|---|---|
| Resistive divider resistor RAC1 | 2.0 MΩ | 3.48 MΩ | |
| Resistive divider resistor RAC2 | 2.0 MΩ | 3.48 MΩ | |
| Sense resistor RAC3 | 10.0 kΩ | 10.0 kΩ | |
| Resulting current through resistive divider IAC | 99.8 µA | 99.0 µA | |
| Resulting voltage drop on sense resistor VRAC3 | ±0.998 V | ±0.990 V | |
Use a power supply with a nominal voltage of 3.3 V for DVDD to directly connect all modulators to the microcontroller.
For modulator output bitstream filtering, a device from TI's TMS320F2807x family of low-cost microcontrollers (MCUs) or TMS320F2837x family of dual-core MCUs is recommended. These MCU families support up to eight channels of dedicated hardwired filter structures called sigma-delta filter modules (SDFMs) that significantly simplify system level design by offering two filtering paths per channel: one providing high accuracy results for the control loop and one that offers a fast response path for overcurrent detection. Use one of the pulse-width modulation (PWM) sources inside the MCU to generate the clock for the modulators and for easy synchronization of all feedback signals and the switching control of the gate drivers.