DC/DC converter
View Patent ↗In a non-isolated DC/DC converter, a reference potential for a low-side pre-driver which drives a gate of a low-side MOSFET is applied from a portion except for a main circuit passing through a high-side MOSFET and the low-side MOSFET so that a parasitic inductance between a source of the low-side MOSFET and the pre-driver is increased without increasing the sum of parasitic inductances in the main circuit and negative potential driving of the gate of the low-side MOSFET can be performed and a self turn-on phenomenon can be prevented without adding any member and changing drive system.
1. A non-isolated DC/DC converter comprising:
a high-side switch;
a low-side switch;
a high-side pre-driver which drives the high-side switch; and
a low-side pre-driver which drives the low-side switch,
wherein a reference potential for the high-side pre-driver which drives a gate of the high-side switch is applied from a potential coupled to between the high-side switch and the low-side switch,
wherein a reference potential for the low-side pre-driver which drives the low-side switch is applied from a reference voltage potential other than said potential coupled to the high-side switch and the low-side switch, and
wherein the reference potential for the low-side pre-driver is applied from a logic ground.
2. The DC/DC converter according to claim 1 ,
wherein said logic ground is connected to a PWM (Pulse Width Modulation) controller coupled to each of the high-side pre-driver and the low-side pre-driver.
3. The DC/DC converter according to claim 1 ,
wherein a Schottky barrier diode is connected between a gate and a source of the low-side switch.
4. The DC/DC converter according to claim 3 ,
wherein the Schottky barrier diode is built-in in a chip on which the low-side switch is disposed.
5. The DC/DC converter according to claim 1 ,
wherein the high-side switch and the low-side switch each comprises a power MOSFET.
6. A non-isolated DC/DC converter using a system-in-package constituted with a high-side switch; a low-side switch; and a driver IC including a high-side pre-driver which drives the high-side switch and a low-side pre-driver which drives the low-side switch in one chip,
wherein a reference potential for the low-side pre-driver which drives the low-side switch is applied from a reference voltage potential other than a potential coupled to the high-side switch and the low-side switch, and
wherein the reference potential for the low-side pre-driver is applied from a logic ground.
7. The DC/DC converter according to claim 6 ,
wherein the reference potential for the low-side pre-driver is applied from a logic ground connected to said low-side driver via a wiring inside the driver IC.
8. The DC/DC converter according to claim 6 ,
wherein the reference potential for the low-side pre-driver is applied from a logic ground connected to said low-side driver by connecting the reference potential and the driver IC with wire bonding.
9. The DC/DC converter according to claim 6 ,
wherein said logic ground is connected to a PWM (Pulse Width Modulation) controller coupled to each of the high-side pre-driver and the low-side pre-driver.
10. The DC/DC converter according to claim 6 ,
wherein a Schottky barrier diode is connected between a gate and a source of the low-side switch.
11. The DC/DC converter according to claim 10 ,
wherein the Schottky barrier diode is built-in on a chip on which the low-side switch is disposed.
12. The DC/DC converter according to claim 6 ,
wherein the high-side switch and the low-side switch each comprises a power MOSFET.
13. A non-isolated DC/DC converter comprising:
a high-side switch;
a low-side switch;
a high-side pre-driver which drives the high-side switch; and
a low-side pre-driver which drives the low-side switch,
wherein a reference potential for the high-side pre-driver which drives a gate of the high-side switch is applied from a potential between the high-side switch and the low-side switch, and
wherein a reference potential for the low-side pre-driver which drives a gate of the low-side switch is applied from a ground terminal of an input capacitor of the DC/DC converter through a wiring pattern on a printed circuit board.
14. The DC/DC converter according to claim 13 ,
wherein a Schottky barrier diode is connected between a gate and a source of the low-side switch.
15. The DC/DC converter according to claim 14 ,
wherein the Schottky barrier diode is built-in in a chip on which the low-side switch is disposed.
16. The DC/DC converter according to claim 13 ,
wherein the high-side switch and the low-side switch each comprises a power MOSFET.
17. A non-isolated DC/DC converter comprising:
a high-side switch;
a low-side switch comprised of a MOSFET;
a high-side pre-driver which drives the high-side switch; and
a low-side pre-driver which drives the low-side switch,
wherein a reference potential for the high-side pre-driver which drives a gate of the high-side switch is applied from a potential coupled to the high-side switch and the low-side switch, and
means for preventing self-turn-on of the low-side switch when the high-side switch is turned ON, said means including means for increasing parasitic inductance between a source of the low-side switch and a reference potential input of the low-side pre-driver by providing a reference potential to the low-side pre-driver other than the reference potential applied from the potential coupled to the high-side switch and the low-side switch, and
wherein the reference potential for the low-side pre-driver is applied from a logic ground.
18. The DC/DC converter according to claim 17 ,
wherein said logic ground is connected to a PWM (Pulse Width Modulation) controller coupled to each of the high-side pre-driver and the low-side pre-driver.