A DCDC power module pre-charge circuit for large array image sensors

Abstract

The application relates to a DCDC power module pre-charging circuit for a large-array image sensor, belonging to the technical field of integrated circuits, which comprises a pre-charging core module, a control switch, multiple groups of parallel current mirrors, a feedback control module and an auxiliary control module; the pre-charging core module is used for generating a fixed charging current and copying the fixed charging current to an output end; the control switch is used for controlling the pre-charging core module to be opened and closed; the current mirror is used for providing a static reference current for the whole pre-charging circuit; the feedback control module is used for continuously and stably providing the charging current when the output current fluctuates; and the auxiliary control module is used for pulling up the control signal when the input voltage is too low, so as to prevent pre-charging failure.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuits and relates to a DCDC power module precharging circuit for a large area array image sensor. Background Art

[0002] In large-area image sensor chips and integrated systems, the pre-charge module in the DCDC power subsystem is a critical component. In the boost circuit, during the initial startup of the circuit, the input voltage of the system is much greater than the output voltage in multiple cycles. This will cause the inductor current to accumulate continuously in multiple cycles. Excessive inductor current will generate surges, thereby endangering the stability of the system. The surge current diagram is shown in the figure below. Figure 1 As shown, a pre-charge circuit is designed to suppress the inrush current, alleviate the possible harm caused by the inrush current, and ensure the stability of the system.

[0003] The traditional charging method is to charge the output capacitor directly through the freewheeling tube, which can be equivalent to an RC circuit. At this time, the converter can be considered to be working in the discharge stage. The inductor current at time t is It can be expressed as , in the absence of loss, the final current is a sine wave, and the peak current is , if the input voltage As can be seen from the formula, a large inrush current will still be generated. Therefore, a pre-charge module is needed to ensure that the inductor current does not exceed the initial startup level until the output voltage rises above the input voltage, at which point the system enters normal amplification mode.

[0004] Therefore, designing a pre-charge module suitable for power supply becomes a key issue in DCDC power supply design. Summary of the Invention

[0005] In view of this, the present invention aims to address the startup stability issue of the DCDC power supply and provide a DCDC power supply module pre-charging circuit for large-area image sensors. By using an amplifier to obtain a reference current, the inductor current does not accumulate continuously during the early stages of system startup, thereby effectively suppressing the inrush current during the initial startup period and ensuring the startup stability of the DCDC power supply.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A DCDC power module pre-charging circuit for large-area array image sensors includes a pre-charging core module, a control switch, multiple sets of parallel current mirrors, a feedback control module, and an auxiliary control module.

[0008] The pre-charging core module is used to generate a fixed charging current and copy the fixed charging current to the output end;

[0009] The control switch is used to control the pre-charging core module to be turned on and off;

[0010] The current mirror is used to provide a static reference current for the entire pre-charging circuit;

[0011] The feedback control module is used to ensure that the charging current can be continuously and stably provided when the output current fluctuates;

[0012] The auxiliary control module is used to prevent pre-charging failure by pulling up the control signal when the input voltage is too low.

[0013] Furthermore, the pre-charging core module includes a transistor M10, a resistor R0 and an amplifier;

[0014] The source of transistor M10 is connected to the input voltage V CC The drain is connected to the reverse input terminal of the amplifier after passing through two sets of current mirrors and is grounded through resistor R0. The gate of M10 is connected to the system power tube M after passing through the control switch. P The gate;

[0015] The amplifier copies the reference current through a current mirror Get the reference voltage , its positive input voltage Equal to the reference voltage , its inverting input terminal is grounded through resistor R0, and its output terminal is connected to the control switch.

[0016] Furthermore, the control switch includes a shielding module Switch, which realizes, through a group of switch tubes, that the pre-charging module is turned on when the control level PG is low, and the pre-charging module is turned off when the control level PG is high.

[0017] Furthermore, the current mirror includes transistors M1 to M9, wherein

[0018] The source of M1 is connected to the operating voltage V int , drain connected reference current , the gate is connected to the gate of M2, and the drain and gate of M1 are short-circuited;

[0019] The source of M2 is connected to the operating voltage V int , the drain is connected to the source of M3;

[0020] The gate of M3 is connected to the control level PG, and the drain of M3 is connected to the drain of M6 and the positive input terminal of the amplifier;

[0021] The source connection resistor R F , resistor R FThe other end of the output voltage , thereby forming a feedback control module, the drain of M4 is connected to the source of M8, and the gate of M4 is connected to the control level PG;

[0022] The source of M5 is connected to the drain of M10, the drain of M5 is connected to the source of M9, and the gate of M5 is connected to the control level PG;

[0023] The source of M6 is connected to the ground, the drain is connected to the positive input of the amplifier, the gate is connected to the gate of M7, and the drain and gate of M6 are short-circuited;

[0024] The source of M7 is connected to the ground, the drain is connected to the drain of M8, and the gate of M7 is connected to the positive input terminal of the amplifier;

[0025] The drain and gate of M8 are short-circuited, and the gate of M8 is connected to the gate of M9;

[0026] The drain of M9 is connected to the inverting input terminal of the amplifier and the resistor R0; the other end of the resistor R0 is connected to the ground.

[0027] Furthermore, the feedback control module is composed of a transistor M4 and a resistor R F Composition, output voltage By R F Generate feedback current Then it is superimposed on the reference voltage generated by R0 through M4, and the feedback current along with Increase Increase, so that the current on M10 Increase to maintain charging current Stablize.

[0028] Furthermore, the amplifier copies the reference current through a current mirror Get the reference voltage , due to the virtual short of the amplifier, the voltage at point A is Equal to the reference voltage , at this time the current on M10 is: ;

[0029] M10 and The current mirror formed by the charging current : ,in Indicates the width-to-length ratio of the P-type power tube. Indicates the width-to-length ratio of the PMOS tube M10.

[0030] Furthermore, the auxiliary control module includes transistors M11 and M12, wherein the source of M11 is connected to the ground line, the gate is connected to the control signal Ctrl, and the drain is connected to the shielding module Switch; the source of M12 is connected to the working voltageV int , the gate is connected to the control signal SSA, and the drain is connected to the shielding module Switch.

[0031] Furthermore, when the input voltage <1.2V, the control signal Ctrl is high, M11 is turned on, and the input voltage Directly charge the output capacitor, and after charging is completed, enter the soft start mode, the SSA signal is pulled low, the PG signal is pulled high, the switch gate is closed, and the pre-charge module enters the sleep mode; when the input voltage When >1.2V, Ctrl is low, M11 is dormant, and the pre-charge circuit works normally.

[0032] The beneficial effect of the present invention is that the present invention reduces the accumulation of inductive current in the initial startup phase through the pre-charging circuit design, thereby suppressing the inrush current during the startup of the DCDC power supply and solving the stability problem of the traditional DCDC power supply during startup.

[0033] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0035] Figure 1 is the surge current diagram;

[0036] Figure 2 This is the pre-charging structure diagram;

[0037] Figure 3 It is a pre-charging circuit;

[0038] Figure 4 This is a simulation diagram of 2V input voltage;

[0039] Figure 5 This is a simulation diagram for 1V input voltage. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0041] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0042] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the embodiments of the present invention.

[0043] Example 1:

[0044] The present invention provides a DC-DC power module precharging circuit for a large-area array image sensor, comprising a precharging core module, a control switch, multiple sets of parallel current mirrors, a feedback control module, and an auxiliary control module. The precharging core module is used to generate a fixed charging current and copy the fixed charging current to an output end. The control switch is used to control the on and off of the precharging core module. The current mirror is used to provide a static reference current for the entire precharging circuit. The feedback control module is used to ensure that the charging current can be continuously and stably provided when the output current fluctuates. The auxiliary control module is used to prevent precharging failure by pulling up a control signal when the input voltage is too low.

[0045] In a specific embodiment, the current mirror includes transistors M1 to M9, wherein the source of M1 is connected to the operating voltage V int , drain connected reference current , the drain and gate are short-circuited, and the gate of M1 is connected to the gate of M2; the source of M2 is connected to the operating voltage V int, the drain is connected to the source of M3; the gate of M3 is connected to the control level PG, the drain of M3 is connected to the drain of M6 and the positive input of the amplifier; the source of M4 is connected to the resistor RF, and the other end of the resistor RF is connected to the output voltage , thereby forming a feedback control module, the drain of M4 is connected to the source of M8, and the gate of M4 is connected to the control level PG; the source of M5 is connected to the drain of M10, the drain of M5 is connected to the source of M9, and the gate of M5 is connected to the control level PG; the source of M6 is connected to the ground, the drain is connected to the positive input of the amplifier, the drain and the gate are short-circuited, and the gate of M6 is connected to the gate of M7; the source of M7 is connected to the ground, the drain is connected to the drain of M8, and the gate of M7 is connected to the positive input of the amplifier; the drain and the gate of M8 are short-circuited, and the gate of M8 is connected to the gate of M9; the drain of M9 is connected to the reverse input of the amplifier and the resistor R0; one end of the resistor R0 is connected to the ground, and the other end is also connected to the reverse input of the amplifier. The auxiliary control module includes transistors M11~M12, among which the source of M11 is connected to the ground, the gate is connected to the control signal Ctrl, and the drain is connected to the shielding module Switch; the source of M12 is connected to the working voltage V int , the gate is connected to the control signal SSA, and the drain is connected to the shielding module Switch.

[0046] Example 2:

[0047] The pre-charge module is used to solve the inrush current at the start-up stage. The charging current is controlled by the reference current through the current mirror. The pre-charge structure is as follows: Figure 2 shown.

[0048] To adapt to low voltage environment, the pre-charge circuit is susceptible to interference and loses its normal function in low voltage environment. Therefore, the pre-charge structure is modified and optimized, and a control module is added to it to reduce the power consumption of DCDC power supply as much as possible. The optimized pre-charge circuit is as follows Figure 3 shown. Figure 3 Medium M P It is the system power tube, Switch is the control switch, and the control switch and its left side are the pre-charge module.

[0049] The working principle of the pre-charge circuit is as follows:

[0050] When the control level PG is low, the switch Switch is turned on, M3, M4, and M5 are turned on, and the pre-charge module starts working. M10, R0, and the amplifier form the pre-charge core module, where R0 and the amplifier are used to generate a fixed charging current, which is then copied to the output end through M10. Vint is the system operating power supply. M1-M9 form a current mirror to provide a static reference current for the entire pre-charge module. The amplifier copies the reference current through the current mirror. Get the reference voltage , due to the virtual short of the amplifier, the voltage at point A is Equal to the reference voltage , at this time the current on M10 is: . By M10 and The current mirror formed can obtain the charging current :

[0051]

[0052] in Indicates the width-to-length ratio of the P-type power tube. Indicates the width-to-length ratio of the PMOS tube M10.

[0053] M4 and RF form the feedback control module of the entire system, which enables the charging current to be continuously and stably provided when the output current fluctuates. The output voltage generates feedback current through RF and then is superimposed on the reference voltage generated by R0 through M4. Gradually increase to near When the power tube It will inevitably enter the linear region, causing the charging current to Drop, introduce feedback current in the pre-charge circuit ,along with Increase Increase, so that the current on M10 Increase to maintain charging current Stable. M11 and M12 form the auxiliary control module of the pre-charge module. In extremely low conditions, the charging current is too small to cause pre-charging failure. In the design of the present invention, the input voltage When <1.2V, the control signal Ctrl is high, M11 is turned on, This causes the potential at point B to be pulled down, and the input voltage Directly charge the output capacitor, and after charging is completed, enter the soft start mode, the SSA signal is pulled low, and the pull-up current This causes the potential of point B to rise, and at the same time PG is pulled high, the switch gate is closed, and the pre-charge module enters sleep mode; the input voltage When the voltage is >1.2V, Ctrl is low, M11 is dormant, and the pre-charge module enters normal working state. , To ensure , in order to ensure that the potential of point B is pulled high during the soft start time. Only exists in low pressure environment, It is a low voltage signal. After the circuit is started Much greater than , which can ensure that the pull-up current is much greater than the pull-down current. The potential at point B is pulled high, and the pre-charge module enters sleep mode. Switch is a pre-charge shielding module. Through a set of switching tubes, the pre-charge module is turned on when the PG voltage is low and turned off when the PG voltage is high, so that the charging current of the pre-charge module no longer affects the system power tube.

[0054] The present invention is simulated under the conditions of 2V input voltage and 1V input voltage, and the simulation results are as follows:

[0055] like Figure 4 As shown, in the case of 2V voltage input, the control signal Ctrl is low, the potential of point B is pulled low, and pre-charging is normal. When the SSA signal is pulled low, the potential of point B is quickly pulled high, and the pre-charging module enters sleep mode.

[0056] like Figure 5 As shown in the figure, when the voltage input is 1V, the control signal Ctrl is high, the potential of point B is pulled down to close to 0V, and the input directly charges the output. When the SSA signal is pulled low and the system potential is high, the potential of point B can still be pulled up to make the pre-charge module enter sleep mode.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A DC-DC power module pre-charging circuit for a large-area image sensor, characterized by: It includes a pre-charging core module, a control switch, multiple sets of parallel current mirrors, a feedback control module and an auxiliary control module; The pre-charging core module is used to generate a fixed charging current and copy the fixed charging current to the output end; The control switch is used to control the pre-charging core module to be turned on and off; The current mirror is used to provide a static reference current for the entire pre-charging circuit; The feedback control module is used to ensure that the charging current can be continuously and stably provided when the output current fluctuates; The auxiliary control module is used to prevent pre-charging failure by pulling up the control signal when the input voltage is too low; The pre-charge core module includes a transistor M10, a resistor R0 and an amplifier; The source of transistor M10 is connected to the input voltage V CC The drain is connected to the resistor R0 and the inverting input terminal of the amplifier after passing through two sets of current mirrors, and is grounded through the resistor R0. The gate of M10 is connected to the system power tube M after passing through the control switch. P The gate; The amplifier copies the reference current through a current mirror Get the reference voltage , its positive input voltage Equal to the reference voltage , its inverting input terminal is grounded through resistor R0, and its output terminal is connected to the control switch; The control switch includes a shielding module Switch, which realizes that the pre-charging module is turned on when the control level PG is low, and the pre-charging module is turned off when PG is high, through a group of switch tubes; The current mirror includes transistors M1 to M9, wherein The source of M1 is connected to the operating voltage V int , drain connected reference current , the gate is connected to the gate of M2, and the drain and gate of M1 are short-circuited; The source of M2 is connected to the operating voltage V int , the drain is connected to the source of M3; The gate of M3 is connected to the control level PG, and the drain of M3 is connected to the drain of M6 and the positive input terminal of the amplifier; The source connection resistor R F , resistor R F The other end of the output voltage , thereby forming a feedback control module, the drain of M4 is connected to the source of M8, and the gate of M4 is connected to the control level PG; The source of M5 is connected to the drain of M10, the drain of M5 is connected to the source of M9, and the gate of M5 is connected to the control level PG; The source of M6 is connected to the ground, the drain is connected to the positive input of the amplifier, the gate is connected to the gate of M7, and the drain and gate of M6 are short-circuited; The source of M7 is connected to the ground, the drain is connected to the drain of M8, and the gate of M7 is connected to the positive input terminal of the amplifier; The drain and gate of M8 are short-circuited, and the gate of M8 is connected to the gate of M9; The drain of M9 is connected to the inverting input terminal of the amplifier and the resistor R0; the other end of the resistor R0 is connected to the ground.

2. The DCDC power module pre-charging circuit for a large area array image sensor according to claim 1, characterized in that: The feedback control module consists of transistor M4 and resistor R F Composition, output voltage By R F Generate feedback current Then it is superimposed on the reference voltage generated by R0 through M4, and the feedback current along with Increase Increase, so that the current on M10 Increase to maintain charging current Stablize.

3. The DCDC power module pre-charging circuit for a large area array image sensor according to claim 2, characterized in that: The amplifier copies the reference current through a current mirror Get the reference voltage , due to the virtual short of the amplifier, the voltage at point A is Equal to the reference voltage , at this time the current on M10 is: ; M10 and The current mirror formed by the charging current : ,in Indicates the width-to-length ratio of the P-type power tube. Indicates the width-to-length ratio of the PMOS tube M10.

4. The DCDC power module pre-charging circuit for a large area array image sensor according to claim 3, characterized in that: The auxiliary control module includes transistors M11 and M12, wherein the source of M11 is connected to the ground line, the gate is connected to the control signal Ctrl, and the drain is connected to the shielding module Switch; the source of M12 is connected to the working voltage V int , the gate is connected to the control signal SSA, and the drain is connected to the shielding module Switch.

5. The DCDC power module pre-charging circuit for a large area array image sensor according to claim 4, characterized in that: When the input voltage <1.2V, the control signal Ctrl is high, M11 is turned on, and the input voltage Directly charge the output capacitor, and after charging is completed, enter the soft start mode, the SSA signal is pulled low, the PG signal is pulled high, the switch gate is closed, and the pre-charge module enters the sleep mode; when the input voltage When >1.2V, Ctrl is low, M11 is dormant, and the pre-charge circuit works normally.

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