Schematic (power path displayed above, full schematic and PCB layout below)
To convert the ideal schematic described in the About page to a functional circuit, additional components are required: sensors, EMI filtering, and a gate drive. The selection of these (among the remainder) components described below.
Resonant Switch Diode (D1=IDK08G65C5)
While this circuit does not require nanosecond reverse recovery on the diodes due to the addition of the resonant inductor, this application still benefits from using SiC diodes. Infineon parts were selected for optimum capacitance. The resonant switch diode is a 650V diode (450v reverse max ideal) rated for 8A continuous.
Buck Diode (D2=IDH10S120)
The addition of the resonant cap C1 slows the transition of D2, hence this application also does not require nanosecond switching. However,to minimize losses, we spec a 10A Infineon SiC diode. At least 900v reverse voltage is required, a 1200v part is used.
Inductors
Inductor specs were generated from the operating point analysis and simulations. Off-the-shelf availability ended up being rather small, thus we chose parts with the lowest losses without significantly increasing volume.
FET (Q1=IPL65R070C7)
This topology has small switching losses and is dominated by conduction losses. We chose a 70mΩ part that was a reasonably tradeoff between area (lower Rdson FETS become physically huge) and conduction loss. This is a 650v part.
EMI Filter (C5=C1812V104KDRACTU L1,L2=35F0121-0SR-10)
This filter consists of a 100nF 1kV ceramic input capacitor and a pair of SMD ferrite beads in front of the input capacitors.
Current Sensing (U3=ACS713ELCTR-20A-T)
This design uses a high-side hall effect current sense. Due to limited bandwidth in the sensor (400khz max), we are unable to perform 'fast' current sense (intra-cycle), and thus we further compromise the bandwidth (down to approximately 100khz) to achieve better noise margins.
Voltage Sensing
Three resistor dividers connected to the MCU's ADC provide voltage measurement.
Gate Drive (Si8233BB-D-IS1)
This design is unusual in that it only requires a single switch (no synchronous rectification), but must be isolated to over 1kv. In order to drive such a large FET, a high-current gate drive is necessary. The selected part has two outputs which are ganged together for double drive current (2x4A=8A) and was chosen as the option with the lowest propagation time across the isolation barrier (around 60ns).
MCU (STM32F3Discovery)
This power converter attaches as a shield on top of a stm32f3discovery board. We had worked with this platform during EE152 and is suits the needs of performance math, ADC resolution/speed, and timer accuracy.
Full Schematic and PCB layout (might be helpful to download images)
To convert the ideal schematic described in the About page to a functional circuit, additional components are required: sensors, EMI filtering, and a gate drive. The selection of these (among the remainder) components described below.
Resonant Switch Diode (D1=IDK08G65C5)
While this circuit does not require nanosecond reverse recovery on the diodes due to the addition of the resonant inductor, this application still benefits from using SiC diodes. Infineon parts were selected for optimum capacitance. The resonant switch diode is a 650V diode (450v reverse max ideal) rated for 8A continuous.
Buck Diode (D2=IDH10S120)
The addition of the resonant cap C1 slows the transition of D2, hence this application also does not require nanosecond switching. However,to minimize losses, we spec a 10A Infineon SiC diode. At least 900v reverse voltage is required, a 1200v part is used.
Inductors
Inductor specs were generated from the operating point analysis and simulations. Off-the-shelf availability ended up being rather small, thus we chose parts with the lowest losses without significantly increasing volume.
FET (Q1=IPL65R070C7)
This topology has small switching losses and is dominated by conduction losses. We chose a 70mΩ part that was a reasonably tradeoff between area (lower Rdson FETS become physically huge) and conduction loss. This is a 650v part.
EMI Filter (C5=C1812V104KDRACTU L1,L2=35F0121-0SR-10)
This filter consists of a 100nF 1kV ceramic input capacitor and a pair of SMD ferrite beads in front of the input capacitors.
Current Sensing (U3=ACS713ELCTR-20A-T)
This design uses a high-side hall effect current sense. Due to limited bandwidth in the sensor (400khz max), we are unable to perform 'fast' current sense (intra-cycle), and thus we further compromise the bandwidth (down to approximately 100khz) to achieve better noise margins.
Voltage Sensing
Three resistor dividers connected to the MCU's ADC provide voltage measurement.
Gate Drive (Si8233BB-D-IS1)
This design is unusual in that it only requires a single switch (no synchronous rectification), but must be isolated to over 1kv. In order to drive such a large FET, a high-current gate drive is necessary. The selected part has two outputs which are ganged together for double drive current (2x4A=8A) and was chosen as the option with the lowest propagation time across the isolation barrier (around 60ns).
MCU (STM32F3Discovery)
This power converter attaches as a shield on top of a stm32f3discovery board. We had worked with this platform during EE152 and is suits the needs of performance math, ADC resolution/speed, and timer accuracy.
Full Schematic and PCB layout (might be helpful to download images)
Full Schematic (might be helpful to download)
Full PCB (might be helpful to download)