Switching converter deadtime control
A circuit includes a controller configured to control switching of a first transistor and a second transistor in switching converter. The controller includes a compensation loop and a deadtime circuit. The compensation loop is configured to provide a compensation value. The deadtime circuit is configured to determine a deadtime value based on the compensation value. The deadtime value defines an interval between turn-off of the first transistor and turn-on of the second transistor.
1 . A circuit comprising:
a controller configured to control switching of a first transistor and a second transistor in a switching converter, the controller including:
a compensation loop including a voltage loop filter configured to provide a compensation value based on an output voltage of the switching converter; and
a deadtime circuit configured to determine a deadtime value based on the compensation value, the deadtime value defining an interval between turn-off of the first transistor and turn-on of the second transistor.
2 . The circuit of claim 1 , wherein the deadtime circuit includes a lookup table storing the deadtime value, and the deadtime circuit is configured to retrieve the deadtime value from the lookup table based on the compensation value.
3 . The circuit of claim 2 , wherein the deadtime circuit includes a shifter circuit configured to right-shift the compensation value by a selected number of bits to produce a shifted compensation value.
4 . The circuit of claim 3 , wherein the deadtime circuit is configured to apply the shifted compensation value to select the deadtime value stored in the lookup table.
5 . The circuit of claim 3 , wherein the selected number of bits is nine.
6 . The circuit of claim 1 , wherein the first transistor is coupled between a power terminal and a switching node, and the second transistor is coupled between the switching node and a reference voltage terminal.
7 . The circuit of claim 1 , wherein the controller is configured to delay turn-on of the second transistor, by a time represented by the deadtime value, after turn-off of the first transistor.
8 . A method, comprising:
calculating a compensation value based on an output voltage of a switching converter by a voltage loop filter of a compensation loop of the switching converter;
selecting a deadtime value based on the compensation value, the deadtime value defining an interval between turn-off of a first transistor and turn-on of a second transistor of the switching converter; and
applying the deadtime value to control switching of the first transistor and the second transistor.
9 . The method of claim 8 , further comprising storing the deadtime value in a lookup table of a controller of the switching converter.
10 . The method of claim 8 , further comprising retrieving the deadtime value from a lookup table of a controller of the switching converter.
11 . The method of claim 10 , further comprising right shifting, by the controller, the compensation value to produce a shifted compensation value.
12 . The method of claim 11 , further comprising applying the shifted compensation value to access the deadtime value stored in the lookup table.
13 . The method of claim 11 , wherein the compensation value is right shifted by nine bits.
14 . The method of claim 8 , further comprising:
turning off the first transistor;
delaying by a time defined by the deadtime value; and
turning on the second transistor after expiration.
15 . A switching converter comprising:
a first transistor and a second transistor coupled in series;
a controller coupled to the first transistor and the second transistor, the controller including:
a compensation loop including a voltage loop filter coupled to a voltage output terminal of the switching converter, the voltage loop filter configured to provide a compensation value based on an output voltage of the switching converter provided at the voltage output terminal; and
a deadtime circuit configured to determine a deadtime value based on the compensation value, the deadtime value defining an interval between turn-off of the first transistor and turn-on of the second transistor.
16 . The switching converter of claim 15 , wherein the deadtime circuit includes a lookup table storing the deadtime value, and the deadtime circuit is configured to retrieve the deadtime value from the lookup table based on the compensation value.
17 . The switching converter of claim 16 , wherein the deadtime circuit includes a shifter circuit configured to right-shift the compensation value by a selected number of bits to produce a shifted compensation value.
18 . The switching converter of claim 17 , wherein the deadtime circuit is configured to apply the shifted compensation value to select the deadtime value stored in the lookup table.
19 . The switching converter of claim 17 , wherein the selected number of bits is nine.
20 . The switching converter of claim 15 , wherein the first transistor is coupled between a power terminal and a switching node, and the second transistor is coupled between the switching node and a reference voltage terminal.