Gate driver, insulation module, low-voltage circuit unit, and high-voltage circuit unit

1. A gate driver that is configured to apply a drive voltage signal to a gate of a switching element, the gate driver comprising:

a low-voltage circuit chip including a low-voltage circuit configured to be actuated by application of a first voltage;

a high-voltage circuit chip including a high-voltage circuit configured to be actuated by application of a second voltage that is higher than the first voltage; and

multiple transformer chips connected in series to each other, wherein

the low-voltage circuit chip and the high-voltage circuit chip are connected by the multiple transformer chips and configured to transmit a signal through the multiple transformer chips, and

each of the multiple transformer chips includes

an insulation layer, and

a first coil and a second coil embedded in the insulation layer and opposed to each other in a thickness-wise direction of the insulation layer.

2. The gate driver according to claim 1 , wherein the multiple transformer chips are arranged next to each other between the low-voltage circuit chip and the high-voltage circuit chip.

3. The gate driver according to claim 1 , further comprising:

a low-voltage die pad on which the low-voltage circuit chip is mounted; and

a high-voltage die pad on which the high-voltage circuit chip is mounted, wherein

the multiple transformer chips include a first transformer chip and a second transformer chip,

the first transformer chip is mounted on the low-voltage die pad, and

the second transformer chip is mounted on the high-voltage die pad.

4. The gate driver according to claim 3 , wherein the first transformer chip and the second transformer chip are separated from each other by a distance that is greater than each of a distance between the first transformer chip and the low-voltage circuit chip and a distance between the second transformer chip and the high-voltage circuit chip.

5. The gate driver according to claim 1 , wherein

the multiple transformer chips include three or more transformer chips,

the gate driver further includes a floating die pad that is electrically floating, and

at least one of the three or more transformer chips is mounted on the floating die pad.

6. The gate driver according to claim 1 , wherein the multiple transformer chips are equal to each other in a distance between the first coil and the second coil.

7. The gate driver according to claim 1 , wherein the first coil and the second coil are formed from a material including Cu.

8. The gate driver according to claim 1 , wherein

each of the transformer chips includes a chip main surface and a chip back surface facing opposite directions in the thickness-wise direction of the insulation layer, and

a dummy pattern is formed around one of the first coil and the second coil that is located closer to the chip main surface.

9. The gate driver according to claim 1 , wherein the multiple transformer chips are identical to each other in structure.

10. The gate driver according to claim 1 , wherein

the signal includes a first signal,

the low-voltage circuit is configured to output the first signal for generating the drive voltage signal based on an external instruction,

the first signal output from the low-voltage circuit is transmitted through the multiple transformer chips to the high-voltage circuit, and

the high-voltage circuit is configured to generate the drive voltage signal based on the first signal from the low-voltage circuit.

11. The gate driver according to claim 1 , wherein

the signal includes a first signal and a second signal,

the multiple transformer chips include

multiple first signal transformer chips connected in series to each other, and

multiple second signal transformer chips connected in series to each other,

the first signal is transmitted from the low-voltage circuit to the high-voltage circuit through the multiple first signal transformer chips, and

the second signal is transmitted from the high-voltage circuit to the low-voltage circuit through the multiple second signal transformer chips.

12. The gate driver according to claim 1 , wherein

one coil of the first and second coils in a first transformer chip of the multiple transformer chips is connected to the low-voltage circuit, and

one coil of the first and second coils in a second transformer chip of the multiple transformer chips is connected to the high-voltage circuit.

13. An insulation module used to insulate a low-voltage circuit from a high-voltage circuit, the low-voltage circuit and the high-voltage circuit being included in a gate driver that is configured to apply a drive voltage signal to a gate of a switching element, the insulation module comprising:

multiple transformer chips connected in series to each other, wherein

the low-voltage circuit and the high-voltage circuit are configured to be connected by the multiple transformer chips,

the multiple transformer chips are used to transmit a signal between the low-voltage circuit and the high-voltage circuit, and

each of the multiple transformer chips includes

an insulation layer, and

a first coil and a second coil embedded in the insulation layer and opposed to each other in a thickness-wise direction of the insulation layer.

14. A low-voltage circuit unit, comprising:

the insulation module according to claim 13 ; and

the low-voltage circuit.

15. A high-voltage circuit unit, comprising:

the insulation module according to claim 13 ; and

the high-voltage circuit.