DC to DC converter and method to transition the DC to DC converter from a buck mode to a boost mode
A DC to DC converter including a buck converter, a boost converter, and a control unit, wherein the control unit is arranged to calculate an error voltage of the buck converter Verr_buck based on a feedback output voltage Vout_FB of the DC to DC converter and a reference voltage of the buck converter Vref_buck, and wherein the control unit is arranged to calculate an error voltage of the boost converter Verr_boost based on the feedback output voltage Vout_FB of the DC to DC converter and a reference voltage of the boost converter Vref_boost, wherein the reference voltage of the boost converter Vref_boost is shifted by an offset Voffset as compared to the reference voltage of the buck converter Vref_buck.
1. A DC to DC converter comprising
a buck converter;
a boost converter; and
a control unit,
wherein the control unit is configured to calculate an error voltage of the buck converter Verr_buck based on a feedback output voltage Vout_FB of the DC to DC converter and a reference voltage of the buck converter Vref_buck, and
wherein the control unit is configured to calculate an error voltage of the boost converter Verr_boost based on the feedback output voltage Vout_FB of the DC to DC converter and a reference voltage of the boost converter Vref_boost, wherein the reference voltage of the boost converter Vref_boost is shifted by an offset Voffset as compared to the reference voltage of the buck converter Vref_buck, and
wherein the control unit is configured to calculate a control signal to engage and disengage the boost converter based on the error voltage of the buck converter Verr_buck, and
wherein the control unit is configured to engage the boost converter when the error voltage of the buck converter Verr_buck is higher than a threshold voltage Vout_of_range, and to disengage the boost converter when the error voltage of the buck converter Verr_buck is lower than the threshold voltage Vout_of_range.
2. The DC to DC converter as claimed in claim 1 ,
wherein the control unit is configured to provide a time-dependent sensing voltage V sens based on an input voltage V in of the DC to DC converter and a pulsating voltage V puls , and
wherein the control unit is further configured to provide a first PWM signal by comparing the time-dependent sensing voltage V sens with the error voltage of the buck converter V err _ buck and to provide a second PWM signal by comparing the time-dependent sensing voltage V sens with the error voltage of the boost converter V err _ boost .
3. The DC to DC converter as claimed in claim 2 , wherein the control unit is configured to provide the first PWM signal and a clock signal as input signals for a HS control circuit that triggers a HS driver circuit for controlling a HS switching element of the buck converter.
4. The DC to DC converter as claimed in claim 2 , wherein the control unit is configured to provide the second PWM signal, a clock signal and the control signal as input signals for a LS control circuit that triggers a LS driver circuit for controlling a LS switching element of the boost converter.
5. A system on a die comprising a DC to DC converter as claimed claim 1 .
6. The DC to DC converter as claimed in claim 1 , wherein the control unit is configured to increase a duty cycle of the buck converter in response to an increase in the error voltage of the buck converter V err _ buck .
7. A method to operate a DC to DC converter including a buck converter, a boost converter, and a control unit, the method comprising:
providing, by the control unit, an error voltage of the buck converter Verr_buck based on a feedback output voltage Vout_FB of the DC to DC converter and a reference voltage of the buck converter Vref_buck;
providing, by the control unit, an error voltage of the boost converter Verr_boost based on the feedback output voltage Vout_FB of the DC to DC converter and a reference voltage of the boost converter Vref_boost, wherein the reference voltage of the boost converter Vref_boost is shifted by an offset Voffset as compared to the reference voltage of the buck converter Vref_buck;
calculating a control signal to engage and disengage the boost converter based on the error voltage of the buck converter Verr_buck;
engaging, by the control unit, the boost converter when the error voltage of the buck converter Verr_buck is higher than a threshold voltage Vout_of_range; and
disengaging, by the control unit, the boost converter when the error voltage of the buck converter Verr_buck is lower than the threshold voltage Vout_of_range.
8. The method as claimed in claim 7 , further comprising:
providing, by the control unit, a time-dependent sensing voltage V sens based on an input voltage V in of the DC to DC converter and a pulsating voltage V puls ;
providing, by the control unit, a first PWM signal by comparing the time-dependent sensing voltage V sens with the error voltage of the buck converter V err _ buck ; and
providing, by the control unit, a second PWM signal by comparing the time-dependent sensing voltage V sens with the error voltage of the boost converter V err _ boost .
9. The method as claimed in claim 8 , further comprising: providing the first PWM signal and a clock signal as input signals for a HS control circuit that triggers a HS driver circuit for controlling a HS switching element of the buck converter.
10. The method as claimed in claim 8 , further comprising: providing the second PWM signal, a clock signal and the control signal as input signals for a LS control circuit that triggers a LS driver circuit for controlling a LS switching element of the boost converter.
11. The method as claimed in claim 7 , further comprising:
increasing a duty cycle of the buck converter in response to an increase in the error voltage of the buck converter V err _ buck .
12. The method as claimed in claim 11 , further comprising:
increasing a duty cycle of the buck converter in response to an increase in the error voltage of the buck converter V err _ buck .
13. A method to operate a DC to DC converter including a buck converter, a boost converter, and a control unit, the method comprising:
providing, by the control unit, an error voltage of the buck converter V err _ buck based on a feedback output voltage V out _ FB of the DC to DC converter and a reference voltage of the buck converter V ref _ buck ;
providing, by the control unit, an error voltage of the boost converter V err _ boost based on the feedback output voltage V out _ FB of the DC to DC converter and a reference voltage of the boost converter V ref _ boost , wherein the reference voltage of the boost converter V ref _ boost is shifted by an offset V offset as compared to the reference voltage of the buck converter V ref _ buck ;
engaging, by the control unit, the boost converter when the error voltage of the buck converter V err _ buck is higher than a threshold voltage V out _ of _ range ; and
disengaging, by the control unit, the boost converter when the error voltage of the buck converter V err _ buck is lower than the threshold voltage V out _ of _ range .
14. The method as claimed in claim 13 , further comprising:
providing, by the control unit, a time-dependent sensing voltage V sens based on an input voltage V in of the DC to DC converter and a pulsating voltage V puls ;
providing, by the control unit, a first pulse width modulated (PWM) signal by comparing the time-dependent sensing voltage V sens with the error voltage of the buck converter V err _ buck ; and
providing, by the control unit, a second PWM signal by comparing the time-dependent sensing voltage V sens with the error voltage of the boost converter V err _ boost .
15. The method as claimed in claim 14 , further comprising:
providing the first PWM signal and a clock signal as input signals for a high side (HS) control circuit that triggers a HS driver circuit for controlling a HS switching element of the buck converter.
16. The method as claimed in claim 15 , wherein the duty cycle of the buck converter is 100 percent before the error voltage of the buck converter V err _ buck is higher than the threshold voltage V out _ of _ range , in response to a value of the threshold voltage V out _ of _ range .
17. The method as claimed in claim 15 , wherein the duty cycle of the boost converter is above 0 percent when the boost converter is engaged in response to a value of the error voltage of the boost converter V err _ boost .
18. The method as claimed in claim 14 , further comprising:
providing the second PWM signal, a clock signal and the control signal as input signals for a low side (LS) control circuit that triggers a LS driver circuit for controlling a LS switching element of the boost converter.