Auto mode change in buck-boost converter
Various embodiments relate to a buck-boost converter controller configured to control a buck-boost controller, wherein the buck-boost converter has a buck mode of operation, a boost mode of operation, and a buck-boost mode of operation, including: a phase controller configured to produce phase control signals to control switching in the buck-boost converter, wherein the phase control signals are based on a mode of operation of the buck-boost converter; and an automatic mode selector configured to indicate to the phase controller the mode of operation of the buck-boost controller based upon a buck on-time TON_bk or a buck off-time TOFF_bk, a boost on-time TON_bst or a boost off-time TOFF_bst, and a control configuration on-time TPI 3 , where TON_bk is the on-time during the buck mode of operation, TOFF_bk is the off-time during the buck mode operation, TON_bst is the on-time during the boost mode of operation, TOFF_bk is the off-time during the boost mode operation, and TPI 3 is the time where a second high-side transistor is on and a first low side transistor is on.
1. A buck-boost converter controller configured to control a buck-boost controller, wherein the buck-boost converter has a buck mode of operation, a boost mode of operation, and a buck-boost mode of operation, comprising:
a phase controller configured to produce phase control signals to control switching in the buck-boost converter, wherein the phase control signals are based on a mode of operation of the buck-boost converter; and
an automatic mode selector configured to indicate to the phase controller the mode of operation of the buck-boost controller based upon a buck on-time TON_bk or a buck off-time TOFF_bk, a boost on-time TON_bst or a boost off-time TOFF_bst, and a control configuration on-time TPI 3 , wherein TON_bk is an on-time during the buck mode of operation, TOFF_bk is the off-time during the buck mode operation, TON_bst is an on-time during the boost mode of operation, TOFF_bk is the off-time during the boost mode operation, and TPI 3 is a time where a second high-side transistor is on and a first low side transistor is on.
2. The buck-boost converter controller of claim 1 , wherein the automatic mode selector is configured to indicate a change from the buck mode to the buck-boost mode when TON_bk is greater than a buck mode threshold or TOFF_bk is less than the buck mode threshold.
3. The buck-boost converter controller of claim 1 , wherein the automatic mode selector is configured to indicate a change from the boost mode to the buck-boost mode when TON_bst is less than a boost mode threshold or TOFF_bk is greater than the boost mode threshold.
4. The buck-boost converter controller of claim 1 , wherein the automatic mode selector is configured to indicate a change from the buck-boost mode to the buck mode when TPI 3 is greater than a first buck-boost mode threshold.
5. The buck-boost converter controller of claim 1 , wherein the automatic mode selector is configured to indicate a change from the buck-boost mode to the boost mode when TPI 3 is less than a second buck-boost mode threshold.
6. The buck-boost converter controller of claim 1 , wherein the automatic mode selector is configured to:
indicate a change from the buck mode to the buck-boost mode when TON_bk is greater than a buck mode threshold or TOFF_bk is less than the buck mode threshold;
indicate a change from the boost mode to the buck-boost mode when TON_bst is less than a boost mode threshold or TOFF_bst is greater than the boost mode threshold;
indicate a change from the buck-boost mode to the buck mode when TPI 3 is greater than a first buck-boost mode threshold; and
indicate a change from the buck-boost mode to the boost mode when TPI 3 is less than a second buck-boost mode threshold.
7. The buck-boost converter controller of claim 1 , further comprising:
a TON_bk generator configured to generate a value of TON_bk based upon an input voltage (Vin) of the buck-boost controller and an output voltage (Vout) of the buck-boost controller; and
a TON_bst generator configured to generate a value of TON_bst based upon Vin and Vout.
8. A buck-boost converter having a buck mode of operation, a boost mode of operation, and a buck-boost mode of operation, comprising:
an H-bridge including a first high-side transistor (HS 1 ), a first low-side transistor (LS 1 ), a second high-side transistor (HS 2 ), and a second low-side transistor (LS 1 );
a first driver configured to drive HS 1 and LS 1 ;
a second driver configured to drive HS 2 and LS 2 ;
a phase controller configured to produce phase control signals including a first driver control signal and a second driver control signal to control switching of HS 1 , LS 1 , HS 2 , and LS 2 , wherein the phase control signals are based on a mode of operation of the buck-boost converter; and
an automatic mode selector configured to indicate to the phase controller the mode of operation of the buck-boost controller based upon a buck on-time TON_bk or a buck off-time TOFF_bk, a boost on-time TON_bst or boost off-time TOFF_bst, and a control configuration on-time TPI 3 , wherein TON_bk is an on-time during the buck mode of operation, TOFF_bk is the off-time during the buck mode operation, TON_bst is an on-time during the boost mode of operation, TOFF_bk is the off-time during the boost mode operation, and TPI 3 is a time where the HS 2 is on and the LS 1 is on.
9. The buck-boost converter of claim 8 , wherein the automatic mode selector is configured to indicate a change from the buck mode to the buck-boost mode when TON_bk is greater than a buck mode threshold or TOFF_bk is less than the buck mode threshold.
10. The buck-boost converter of claim 8 , wherein the automatic mode selector is configured to indicate a change from the boost mode to the buck-boost mode when TON_bst is less than a boost mode threshold of TOFF_bst is greater than the boost mode threshold.
11. The buck-boost converter of claim 8 , wherein the automatic mode selector is configured to indicate a change from the buck-boost mode to the buck mode when TPI 3 is greater than a first buck-boost mode threshold.
12. The buck-boost converter of claim 8 , wherein the automatic mode selector is configured to indicate a change from the buck-boost mode to the boost mode when TPI 3 is less than a second buck-boost mode threshold.
13. The buck-boost converter of claim 8 , wherein the automatic mode selector is configured to:
indicate a change from the buck mode to the buck-boost mode when TON_bk is greater than a buck mode threshold or TON_bk is less than the buck mode threshold;
indicate a change from the boost mode to the buck-boost mode when TON_bst is less than a boost mode threshold or TOFF_bst is greater than the boost mode threshold;
indicate a change from the buck-boost mode to the buck mode when TPI 3 is greater than a first buck-boost mode threshold; and
indicate a change from the buck-boost mode to the boost mode when TPI 3 is less than a second buck-boost mode threshold.
14. The buck-boost converter of claim 8 , further comprising:
a TON_bk generator configured to generate a value of TON_bk based upon an input voltage (Vin) of the buck-boost controller and an output voltage (Vout) of the buck-boost controller; and
a TON_bst generator configured to generate a value of TON_bst based upon Vin and Vout.
15. A method for controlling a buck-boost converter, wherein the buck-boost converter has a buck mode of operation, a boost mode of operation, and a buck-boost mode of operation, comprising:
producing phase control signals, by a phase controller, to control switching in the buck-boost converter, wherein the phase control signals are based on a mode of operation of the buck-boost converter; and
indicating to the phase controller the mode of operation of the buck-boost controller based upon a buck on-time TON_bk or a buck off-time TOFF_bk, a boost on-time TON_bst or a boost off-time TOFF_bst, and a control configuration on-time TPI 3 , wherein TON_bk is an on-time during the buck mode of operation, TOFF_bk is the off-time during the buck mode operation, TON_bst is an on-time during the boost mode of operation, TOFF_bk is the off-time during the boost mode operation, and TPI 3 is a time where a second high-side transistor is on and a first low side transistor is on.
16. The method of claim 15 , further comprises indicating a change from the buck mode to the buck-boost mode when TON_bk is greater than a buck mode threshold or TOFF_off is less than the buck mode threshold.
17. The method of claim 15 , further comprises indicating a change from the boost mode to the buck-boost mode when TON_bst is less than a boost mode threshold or TOFF_bst is greater than the boost mode threshold.
18. The method of claim 15 , further comprises indicating a change from the buck-boost mode to the buck mode when TPI 3 is greater than a first buck-boost mode threshold.
19. The method of claim 15 , further comprises indicating a change from the buck-boost mode to the boost mode when TPI 3 is less than a second buck-boost mode threshold.
20. The method of claim 15 , further comprising:
indicating a change from the buck mode to the buck-boost mode when TON_bk is greater than a buck mode threshold or TOFF_bk is less than the buck mode threshold;
indicating a change from the boost mode to the buck-boost mode when TON_bst is less than a boost mode threshold or TON_bst is greater than the boost mode threshold;
indicating a change from the buck-boost mode to the buck mode when TPI 3 is greater than a first buck-boost mode threshold; and
indicating a change from the buck-boost mode to the boost mode when TPI 3 is less than a second buck-boost mode threshold.