Buck Converter | PartQuest™ Explore

Application Area

mike.zeng
Designer232739

mike.zeng

Member for

4 years 4 months

6

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

This design is a detailed circuit implementation of the more abstract "state-average" buck converter model shown in the companion design example: “Step-Down (Buck) DC to DC Converter - Continuous”. This example includes the low-pass voltage sense circuit, an op-amp implementation of the difference amplifier and the lead-lag compensator, as well as PWM switching control of a power MOSFET. Simulation results for the line and load transients are very similar to the results from the continuous model.

This design uses a number of "datasheet characterized" components, including the power MOSFET (MCH6337), freewheel diode (NRVTS560EMFS) and op-amps (MC33272A), as well as the soft-saturation inductor (XAL6060-223) and capacitor (PEG127KA3110Q) of the power stage . The parameter values of these devices were entered directly from the datasheet for the corresponding part, including the "Maximum Ratings" information.

While the simulation time for this switching circuit is significantly longer than for the abstract model, more detailed information about the circuit’s signals and components is available. This includes the component stress levels, which are monitored within all the "datasheet" models.

The companion design, "TDFS Loop Stability for Step-Down (Buck) DC to DC Converter - Switching", demonstrates a method to directly assess the open-loop frequency response, and hence the stability margin, of this converter. The TDFS (Time Domain Frequency Sweep) method circumvents the need for state-average models of the switching elements.

About text formats

Copy of C-7. Buck Converter 2-Phase Vo=250V Io=40A - on Fri, 06/26/2020 - 16:54

Takayuki
Designer224194

Takayuki

Member for

5 years 1 month

492

designs

4

groups

A member of the PartQuest Explore community.

Copy of C-7. Buck Converter 2-Phase Vo=250V Io=40A - on Fri, 06/26/2020 - 16:28

Takayuki
Designer224194

Takayuki

Member for

5 years 1 month

492

designs

4

groups

A member of the PartQuest Explore community.

Copy of C-7. Buck Converter 2-Phase Vo=250V Io=40A - on Fri, 06/26/2020 - 15:53

HA_1
Designer225347

HA_1

Member for

5 years

28

designs

1

groups

Copy of C-7. Buck Converter 2-Phase Vo=250V Io=40A - on Fri, 06/26/2020 - 15:53

HA_1
Designer225347

HA_1

Member for

5 years

28

designs

1

groups

Copy of C-7. Buck Converter 2-Phase Vo=250V Io=40A - on Fri, 06/26/2020 - 15:53

HA_1
Designer225347

HA_1

Member for

5 years

28

designs

1

groups

Copy of C-7. Buck Converter 2-Phase Vo=250V Io=40A - on Fri, 06/26/2020 - 15:53

HA_1
Designer225347

HA_1

Member for

5 years

28

designs

1

groups

Copy of NCV891930MW01 Virtual Demo Board - on Fri, 05/29/2020 - 13:06

Devon Johnson
Designer250

Devon Johnson

Member for

9 years 7 months

49

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

This version of the NCV891930MW01 "Virtual Evaluation Board" represents most of the features of the 3.65 V/4.0V output part. By changing various input stimulus and loading conditions, you can test these capabilities in the context of their intended usage.

For the nominal configuration, the input voltage is set to 12V, the synci source is delayed for 10 msec (well beyond the simulation end-time), and the load resistance is fixed at 1 Ohm until 500 us, then it jumps to 10 kOhm for 100 us, then back to 1 Ohm. The soft-start operates normally, but during the high resistance operation of the load transient, a single pulse-skip interval is observed. You can zoom in on the PWM signal and see that only two 500 kHz pulses were applied during the “burst” interval, but it will generate 3 pulses under other operating conditions. You can also see that the PWM frequency is spread-spectrum after the soft-start is complete, by measuring the clock frequency (as a waveform) in the main waveform viewer.

To test the “GH continuous ON” behavior, you can select the “DC” option in the load resistance function generator to set the value to a fixed 1 Ohm, and set the input voltage to 5.5V. In the simulation you'll observe several long periods of "continuous GH" operation, with 200 ns boost recharge windows every 16 us, after soft-start has finished.

To test SYNCI operation, set the input voltage to 12V and the load resistance to “Pulse” (i.e. back to their original values), and then change the synci source delay to 10 ns (instead of 10 ms). Then the device will operate in forced PWM mode, with negative inductor currents allowed during the high load resistance period (i.e. not diode-emulation), and no pulse-skip.

Other features can also be tested (high voltage frequency fold-back, output voltage select, LDO bypass jumper removed, etc.). In addition, you can force abnormal operating states using the two fixed logic sources available in the lower left corner of the schematic. For example, if the controller signal “d_spread_spectrum” is disconnected right at the input to the oscillator, and then a new net is connected from “d_set0” to that open input port, then the oscillator's spread-spectrum function will be disabled regardless of the normal controller commanded behavior.

Notes:

(1) Because a simplified version of the resistor divider network and compensation is used, the model will regulate above the target output voltage at light loads. The the real IC will regulate within specifications.

(2) In order to reduce the simulation time, the softstart capacitor value has been adjusted to reduce the softstart time. The value used in this project does not reflect the suggested value from the evaluation board schematic. The desired capacitor value should be selected based on the equation provided in the datasheet.

About text formats

Copy of Step-Down (Buck) DC to DC Converter - Switching - on Fri, 05/22/2020 - 11:42

ivanildosistema
Designer232022

ivanildosistema

Member for

4 years 6 months

3

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

This design is a detailed circuit implementation of the more abstract "state-average" buck converter model shown in the companion design example: “Step-Down (Buck) DC to DC Converter - Continuous”. This example includes the low-pass voltage sense circuit, an op-amp implementation of the difference amplifier and the lead-lag compensator, as well as PWM switching control of a power MOSFET. Simulation results for the line and load transients are very similar to the results from the continuous model.

This design uses a number of "datasheet characterized" components, including the power MOSFET (MCH6337), freewheel diode (NRVTS560EMFS) and op-amps (MC33272A), as well as the soft-saturation inductor (XAL6060-223) and capacitor (PEG127KA3110Q) of the power stage . The parameter values of these devices were entered directly from the datasheet for the corresponding part, including the "Maximum Ratings" information.

While the simulation time for this switching circuit is significantly longer than for the abstract model, more detailed information about the circuit’s signals and components is available. This includes the component stress levels, which are monitored within all the "datasheet" models.

The companion design, "TDFS Loop Stability for Step-Down (Buck) DC to DC Converter - Switching", demonstrates a method to directly assess the open-loop frequency response, and hence the stability margin, of this converter. The TDFS (Time Domain Frequency Sweep) method circumvents the need for state-average models of the switching elements.

About text formats

Copy of C-6. Buck Converter Vo=250V Io=20A - on Mon, 05/18/2020 - 11:57

Shin_1
Designer224531

Shin_1

Member for

5 years 1 month

107

designs

2

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Terms of Use Cookie Notice Data Privacy Notice

mike.zengDesigner232739

Member for

TakayukiDesigner224194

Member for

TakayukiDesigner224194

Member for

HA_1Designer225347

Member for

HA_1Designer225347

Member for

HA_1Designer225347

Member for

HA_1Designer225347

Member for

Devon JohnsonDesigner250

Member for

ivanildosistemaDesigner232022

Member for

Shin_1Designer224531

Member for

mike.zeng
Designer232739

Takayuki
Designer224194

Takayuki
Designer224194

HA_1
Designer225347

HA_1
Designer225347

HA_1
Designer225347

HA_1
Designer225347

Devon Johnson
Designer250

ivanildosistema
Designer232022

Shin_1
Designer224531