US-20260128611-A1 - INTEGRATED CIRCUIT WITH POWER LOSS PROTECTION FUNCTION

Abstract

An integrated circuit with power loss protection function, including a bus terminal configured to provide a bus voltage, an energy storage terminal configurable to be coupled to a power loss protection capacitor, a charging circuit coupled between the bus terminal and the energy storage terminal, and a capacitance monitoring circuit. The charging circuit includes a first charging path, and based on the bus voltage, provides a first constant charging current to charge the power loss protection capacitor during a first constant charging period in a startup process of the integrated circuit. The capacitance monitoring circuit monitors the voltage across the power loss protection capacitor in the charging period of the startup process of the integrated circuit to obtain a parameter for calculating the capacitance value of the power loss protection capacitor.

Inventors

• Hang Yang
• Bo Li
• Haitang Wang
• Pengjie Lai

Assignees

• CHENGDU MONOLITHIC POWER SYSTEMS CO., LTD.

Dates

Publication Date

20260507

Application Date

20251104

Priority Date

20241105

Claims (20)

1. 1 . An integrated circuit with power loss protection function, comprising: a bus terminal configured to provide a bus voltage; an energy storage terminal configurable to be coupled to a power loss protection capacitor; a charging circuit, coupled between the bus terminal and the energy storage terminal, configured to charge the power loss protection capacitor with the bus voltage when the power loss protection capacitor is coupled to the energy storage terminal, wherein the charging circuit comprises a first charging path configured to charge the power loss protection capacitor based on the bus voltage during a charging period in a startup process of the integrated circuit, and wherein the charging period includes at least a first constant charging period during which the first charging path is further configured to at least provide a first constant charging current to charge the power loss protection capacitor, such that a voltage across the power loss protection capacitor rises at a first fixed slop; and a capacitance monitoring circuit configured to monitor a voltage across the power loss protection capacitor when the power loss protection capacitor is coupled to the energy storage terminal, in the charging period of the startup process of the integrated circuit, to obtain a parameter for calculating a capacitance value of the power loss protection capacitor.
2. 2 . The integrated circuit of claim 1 , wherein the capacitance monitoring circuit is further configured to, during the first constant charging period, obtain a first time period for the voltage across the power loss protection capacitor to rise from a first threshold voltage to a second threshold voltage, and wherein the second threshold voltage is higher than the first threshold voltage, and wherein the parameter comprises the first time period.
3. 3 . The integrated circuit of claim 2 , wherein the capacitance monitoring circuit is further configured to obtain the capacitance value of the power loss protection capacitor at least based on the first time period, the first threshold voltage, the second threshold voltage, and the first constant charging current.
4. 4 . The power management circuit of claim 2 , wherein the capacitance monitoring circuit is configured to obtain the capacitance value of the power loss protection capacitor at least based on the following equation: C = I CH ⁢ 1 * T ⁢ 1 / ( V TH ⁢ 2 - V T ⁢ H ⁢ 1 ) , and wherein the C represents the capacitance value of the power loss protection capacitor, the I CH1 represents the first constant charging current value, the V TH1 represents the first threshold voltage, the V TH2 represents the second threshold voltage, and the T1 represents the first time period.
5. 5 . The integrated circuit of claim 1 , wherein the charging period further includes a second constant charging period; and wherein the first charging path is further configured to provide a second constant charging current during the second constant charging period to the power loss protection capacitor to charge the power loss protection capacitor such that the voltage across the power loss protection capacitor rises at a second fixed slope; and wherein the first constant charging current and the second constant charging current are unequal and proportional.
6. 6 . The integrated circuit of claim 5 , wherein the capacitance monitoring circuit is configured to obtain a first time period for the voltage across the power loss protection capacitor to rise from the first threshold voltage to the second threshold voltage during the first constant charging period, and obtain a second time period for the voltage across the power loss protection capacitor to rise from a third threshold voltage to a fourth threshold voltage during the second constant charging period, and wherein the parameter comprises the first time period and the second time period, and wherein the fourth threshold voltage is higher than the third threshold voltage, and the second threshold voltage is higher than the first threshold voltage.
7. 7 . The integrated circuit of claim 6 , wherein the third threshold voltage is equal to the first threshold voltage and the fourth threshold voltage is equal to the third threshold voltage.
8. 8 . The integrated circuit of claim 6 , wherein a difference between the second threshold voltage and the first threshold voltage is proportional to a difference between the fourth threshold voltage and the third threshold voltage.
9. 9 . The integrated circuit of claim 6 , wherein a difference between the second threshold voltage and the first threshold voltage is equal to a difference between the fourth threshold voltage and the third threshold voltage.
10. 10 . The integrated circuit of claim 9 , wherein the capacitance monitoring circuit is configured to obtain the capacitance value of the power loss protection capacitor at least based on: the first time, the second time, the first threshold voltage, the second threshold voltage, the first constant charging current, and a ratio of the first constant charging current to the second constant charging current.
11. 11 . The integrated circuit according of 9 , wherein the capacitance monitoring circuit is configured to obtain the capacitance value of the power loss protection capacitor based on the following equation: C = ( K ⁢ 1 - 1 ) * T ⁢ 1 * T ⁢ 2 * I CH ⁢ 1 / ( T ⁢ 1 - T ⁢ 2 ) * ( V TH ⁢ 2 - V TH ⁢ 1 ) , and wherein the C represents a capacitance value of the power loss protection capacitor, the I CH1 represents the first constant charging current value, the K1 represents a ratio of the second constant charging current to the first constant charging current, the T1 represents the first time period, the T2 represents the second time period, the V TH1 represents the first threshold voltage, and the V TH2 represents the second threshold voltage.
12. 12 . A capacitance monitoring method for a power loss protection capacitor, the method being performed by an integrated circuit with a power loss protection function and comprising: charging the power loss protection capacitor based on the bus voltage during a charging period in the startup process of the integrated circuit, and wherein the charging period includes at least a first constant charging period; providing a first constant charging current to the power loss protection capacitor to charge the power loss protection capacitor during the first constant charging period, such that a voltage across the power loss protection capacitor rises at a first fixed slope; and monitoring a voltage across the power loss protection capacitor in the charging period of the startup process of the integrated circuit, to obtain a parameter for calculating a capacitance value of the power loss protection capacitor.
13. 13 . The method of claim 12 , wherein the obtaining parameter for calculating the capacitance value of the power loss protection capacitor comprising: during the first constant charging period, obtaining a first time period for the voltage across the power loss protection capacitor to rise from a first threshold voltage to a second threshold voltage, and wherein the second threshold voltage is higher than the first threshold voltage, and wherein the parameter comprises the first time period.
14. 14 . The method of claim 13 , further comprising: obtaining the capacitance value of the power loss protection capacitor at least based on, the first time period, the first threshold voltage, the second threshold voltage, and the first constant charging current.
15. 15 . The method of claim 13 , further comprising: obtaining the capacitance value of the power loss protection capacitor at least based on the following equation: C = I CH ⁢ 1 * T ⁢ 1 / ( V TH ⁢ 2 - V T ⁢ H ⁢ 1 ) , wherein the C represents the capacitance value of the power loss protection capacitor, the I CH1 represents the first constant charging current value, the V TH1 represents the first threshold voltage, the V TH2 represents the second threshold voltage, and the T1 represents the first time period.
16. 16 . The method of claim 12 , wherein the charging period further includes a second constant charging period; and wherein the method further comprises: providing a second constant charging current during the second constant charging period to the power loss protection capacitor to charge the power loss protection capacitor such that the voltage across the power loss protection capacitor rises at a second fixed slope; and wherein the first constant charging current and the second constant charging current are unequal and proportional.
17. 17 . The method of claim 16 , further comprising: during the first constant charging period, obtaining the first time period for the voltage across the power loss protection capacitor to rise from the first threshold voltage to the second threshold voltage, and during the second constant charging period, obtaining a second time period for the voltage across the power loss protection capacitor to rise from the third threshold voltage to the fourth threshold voltage, wherein the parameter comprises the first time period and the second time period, and wherein the fourth threshold voltage is higher than the third threshold voltage, and the second threshold voltage is higher than the first threshold voltage.
18. 18 . The method of claim 17 , wherein the third threshold voltage is equal to the first threshold voltage and the fourth threshold voltage is equal to the third threshold voltage.
19. 19 . The method of claim 17 , wherein a difference between the second threshold voltage and the first threshold voltage is proportional to a difference between the fourth threshold voltage and the third threshold voltage.
20. 20 . The method of claim 17 , wherein a difference between the second threshold voltage and the first threshold voltage is equal to a difference between the fourth threshold voltage and the third threshold voltage.

Description

CROSS-REFERENCE The present application claims priority to, and the benefit of, Chinese Application No. 202411565018.6 filed on Nov. 5, 2024, which is incorporated herein by reference in its entirety. TECHNICAL FIELD This present application generally relates to electronic circuits, more particularly but not limited to integrated circuits with power loss protection function and methods for monitoring capacitance values of power loss protection capacitors. BACKGROUND In certain conventional power management circuits for uninterrupted power supply applications, a backup power source is typically provided to sustain power delivery to an application device during unexpected loss of external power supply. For example, in a conventional switching power supply for providing a bus voltage to a downstream device such as a DC-DC converter for supplying a Solid State Driver (SSD), a power loss protection capacitor with relatively high nominal voltage commonly serve as the backup power source when a preset condition is met (e.g., when the bus voltage drops to a release threshold). According to the energy storage principles of the capacitor, the energy stored in a capacitor is proportional to the capacitance value of the capacitor. However, as the capacitor ages over time, the capacitance value decreases and the energy it can store decreases accordingly. In some applications, when the energy stored in a power loss protection capacitor decreases to a certain level, it may no longer function as the backup power source. Therefore, it is necessary to effectively monitor the capacitance value of the power loss protection capacitor while reducing the interference with normal circuit operations. SUMMARY There has been provided, in accordance with an embodiment of the present invention, an integrated circuit with power loss protection function, including: a bus terminal, an energy storage terminal, a charging circuit and a capacitance monitoring circuit. The bus terminal is configured to provide a bus voltage. The energy storage terminal is configurable to be coupled to a power loss protection capacitor. The charging circuit is coupled between the bus terminal and the energy storage terminal and is configured to charge the power loss protection capacitor using the bus voltage when the power loss protection capacitor is coupled to the energy storage terminal. The charging circuit includes a first charging path configured to charge the power loss protection capacitor based on the bus voltage during a charging period in a startup process of the integrated circuit, and the charging period includes at least a first constant charging period during which the first charging path is further configured to at least provide a first constant charging current to charge the power loss protection capacitor, such that a voltage across the power loss protection capacitor rises at a first fixed slope. The capacitance monitoring circuit is configured to monitor a voltage across the power loss protection capacitor when the power loss protection capacitor is coupled to the energy storage terminal, in the charging period of the startup process of the integrated circuit, to obtain a parameter for calculating a capacitance value of the power loss protection capacitor. Another embodiment of the present invention provides a method for capacitance monitoring for a power loss protection capacitor. The method is executed by an integrated circuit with power loss protection function and includes the following steps. Charging the power loss protection capacitor based on the bus voltage during a charging period in the startup process of the integrated circuit, and the charging period includes at least a first constant charging period. Providing a first constant charging current to charge the power loss protection capacitor during the first constant charging period, such that a voltage across the power loss protection capacitor rises at the first fixed slope. Monitoring a voltage across the power loss protection capacitor in the charging period of the startup process of the integrated circuit, to obtain a parameter for calculating a capacitance value of the power loss protection capacitor. It should be understood that the description described in this section is not intended to identify key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will be easily understood from the following specification. BRIEF DESCRIPTION OF DRAWINGS For a better understanding of the present invention, embodiments thereof will be described with reference to below drawings, which are provided for illustrative purpose only. The drawings generally illustrate only certain features of the embodiments and are not necessarily drawn to scale. FIG. 1 illustrates a block diagram of a power management circuit with power loss protection function in accordance with an embo