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EP-4738705-A1 - A SWITCHED MODE POWER SUPPLY, SMPS, CIRCUIT HAVING AN ELECTROSTATIC DISCHARGE, ESD, PROTECTION CIRCUIT, AS WELL AS A CORRESPONDING METHOD

EP4738705A1EP 4738705 A1EP4738705 A1EP 4738705A1EP-4738705-A1

Abstract

A Switched Mode Power Supply, SMPS, circuit, comprising an SMPS comprising a driver and a low-side switch responsible for regulating power flow to an output of said SMPS circuit, wherein said driver is arranged for controlling said low-side switch and wherein said SMPS operates in a second power domain, a level-shifter circuit arranged for translating signals from a first power domain to the second power domain, an ElectroStatic Discharge, ESD, protection circuit arranged for detecting an ESD event and for enabling said low-side switch upon detection of said ESD event, wherein said ESD protection circuit is implemented in said level-shifter circuit and is connected to a voltage supply in said first power domain.

Inventors

  • OLIVARES, JAIRO
  • VERA, ALEJANDRO
  • MURTAZA, SYED SUHAIL

Assignees

  • Nexperia B.V.

Dates

Publication Date
20260506
Application Date
20251031

Claims (15)

  1. A Switched Mode Power Supply, SMPS, circuit, comprising: - an SMPS comprising a driver and a low-side switch responsible for regulating power flow to an output of said SMPS circuit, wherein said driver is arranged for controlling said low-side switch and wherein said SMPS operates in a second power domain; - a level-shifter circuit arranged for translating signals from a first power domain to the second power domain; - an ElectroStatic Discharge, ESD, protection circuit arranged for detecting an ESD event and for enabling said low-side switch upon detection of said ESD event, wherein said ESD protection circuit is implemented in said level-shifter circuit and is connected to a voltage supply in said first power domain.
  2. An SMPS circuit in accordance with claim 1, wherein the ESD protection circuit comprises: - a Field Effect Transistor, FET, connected in series with a resistor, wherein a gate of said FET is connected to said voltage supply in said first power domain.
  3. An SMPS circuit in accordance with claim 2, wherein the level-shifter circuit comprises a cross-coupled inverter, wherein the ESD protection circuit is connected to an output of the cross-coupled inverter.
  4. An SMPS circuit in accordance with claim 3, wherein the ESD protection circuit is connected to a ground corresponding to said first power domain.
  5. An SMPS circuit in accordance with claim 4, wherein the ESD protection circuit is arranged for pulling said output of said cross-coupled inverters to said ground during said ESD event.
  6. An SMPS circuit in accordance with any of the previous claims, wherein the level-shifter circuit is arranged to receive a control signal, in said first power domain, for controlling said low-side switch and for translating said control signal to said second power domain.
  7. An SMPS circuit in accordance with any of the previous claims, wherein said low-side switch is a Field Effect Transistor, FET.
  8. An SMPS circuit in accordance with any of the previous claims, wherein said SMPS is any of a synchronous buck converter, boost converter, flyback converter.
  9. A method of controlling a Switched Mode Power Supply, SMPS, circuit in accordance with any of the previous claims, wherein said method comprises the steps of: - detecting, by said ESD protection circuit, said ESD event, and - enabling, by said ESD protection circuit upon detection of said ESD event, said low-side switch.
  10. A method in accordance with claim 9, wherein the ESD protection circuit comprises: - a Field Effect Transistor, FET, connected in series with a resistor, wherein a gate of said FET is connected to said voltage supply in said first power domain.
  11. A method in accordance with claim 10, wherein the level-shifter circuit comprises a cross-coupled inverter, wherein the ESD protection circuit is connected to an output of the cross-coupled inverter.
  12. A method in accordance with claim 11, wherein the ESD protection circuit is connected to a ground corresponding to said first power domain.
  13. A method in accordance with claim 12, wherein the ESD protection circuit is arranged for pulling said output of said cross-coupled inverters to said ground during said ESD event.
  14. A method in accordance with any of the claims 9 - 13, wherein the method comprises the steps of: - receiving, by the level-shifter circuit, a control signal, in said first power domain, and - translating, by the level-shifter circuit, said received control signal to said second power domain.
  15. A method in accordance with any of the claims 9 - 14, wherein said SMPS is any of a buck converter, boost converter, flyback converter.

Description

Technical field The present disclosure generally relates to the field of Switched Mode Power Supplies, SMPS, and, more specifically, to an SMPS having an efficient ElectroStatic Discharge, ESD, protection circuit. Background A switched-mode power supply, SMPS, is an electronic power converter that uses a switching regulator to convert electrical power. It is widely used in various applications, including computers, telecommunications, and industrial systems, because of its high efficiency and compact design. Unlike linear power supplies, which operate continuously in their linear region, SMPS works by rapidly switching the load on and off using semiconductor devices like Metal Oxide Semiconductor Field Effect Transistors, MOSFETs, to control the input and output voltage. This high-speed switching allows SMPS to maintain high efficiency while regulating voltage levels for various electronic devices. In a buck converter, which is a specific type of switched-mode power supply, the design incorporates typically large MOSFETs that alternately conduct current from the input to the output or from ground to the output during each switching cycle. This converter is primarily used to step down a higher input voltage to a lower output voltage by switching at a high frequency. Components such as inductors and capacitors are utilized to smooth out the output voltage. However, the rapid switching involved in this process introduces certain challenges, including electromagnetic interference, EMI, voltage spikes, and susceptibility to electrostatic discharge, ESD, events. An ESD event occurs when a sudden discharge of static electricity takes place between two objects with differing electrical potentials. Such events can be caused by human contact, handling of sensitive components, or even environmental conditions. In the context of an SMPS, ESD may pose a risk to the large (power) MOSFETs and other internal circuitry. The voltage buildup between the switch node pin and ground during an ESD event can exceed the rated voltage of the MOSFETs, leading to permanent damage. This failure may manifest as a short circuit or complete breakdown of the MOSFET, which in turn compromises the functionality of the power supply. Additionally, other components like gate drivers, capacitors, and control circuits may also be vulnerable to damage during such events. To mitigate the risk of ESD in a switched-mode power supply, several protection strategies are commonly implemented. One widely used approach is the incorporation of transient voltage suppression, TVS, diodes. These diodes are designed to clamp high-voltage transients, absorbing the excess energy generated during an ESD event and preventing it from reaching critical components like the MOSFETs. When an ESD event occurs, the TVS diode temporarily switches to a lowresistance state, diverting the transient energy to ground and protecting the sensitive components. Once the event passes, the diode returns to its high-resistance state, allowing normal operation to resume. Another common technique is the use of snubber circuits, which consist of resistors and capacitors placed across the MOSFETs. Snubber circuits help absorb voltage spikes that occur due to parasitic inductance during switching. Since the rapid current changes during switching can generate voltage spikes across the MOSFETs, these spikes become more pronounced during an ESD event. By absorbing these spikes, snubber circuits ensure that the voltage across the MOSFETs remains within safe limits. Downsides of the known techniques is that they are either large or cumbersome of not suitable to be implemented on a semiconductor device. Summary It would be advantageous to achieve a Switched Mode Power Supply, SMPS, that has an efficient ElectroStatic Discharge, ESD, protection circuit. It would further be advantageous to achieve a corresponding method. In a first aspect of the present disclosure, there is provided a Switched Mode Power Supply, SMPS, circuit. The SMPS circuit comprising: an SMPS comprising a driver and a low-side switch responsible for regulating power flow to an output of said SMPS circuit, wherein said driver is arranged for controlling said low-side switch and wherein said SMPS operates in a second power domain;a level-shifter circuit arranged for translating signals from a first power domain to the second power domain;an ElectroStatic Discharge, ESD, protection circuit arranged for detecting an ESD event and for enabling said low-side switch upon detection of said ESD event, wherein said ESD protection circuit is implemented in said level-shifter circuit and is connected to a voltage supply in said first power domain. In the SMPS circuit, a level-shifter circuit is used to interface between the two power domains that operate at different, or the same, voltage levels. Its primary function is to translate the voltage level of signals from the first power domain to a compatible voltage level for the second power