Rectification step-down power supply module

Abstract

The utility model relates to the technical field of power supply modules, and discloses a rectification step-down power supply module, comprising a grounding pin PGND which is used for adjusting output voltage reference grounding. When the PCB is arranged, the GND is connected in a copper-clad mode with a via hole, an output pin SW is connected to an output capacitor COUT, an output pin OUT is connected to the output capacitor COUT, a bootstrap pin BST is arranged, the bootstrap capacitor is arranged between the SW and the BST pin, power is supplied to an internal upper tube switch drive, an enabling pin EN is arranged, a module can be enabled by pulling up the EN pin, when the module is suspended, the EN pin is pulled down to the GND through an internal 3.3 megohm resistor, and the GND is connected to the output capacitor COUT through the internal 3.3 megohm resistor. When the module is forbidden, a feedback pin is FB, and the FB is connected to an external resistance voltage divider between the output and the GND so as to set the output voltage, the module provided by the utility model provides a constant on-time control mode (COT), so that the frequency jitter can be improved, and the stability of the module can be improved by providing a fast transient response and a slope compensation function.

Description

Technical Field

[0001] The utility model relates to the technical field of power modules, and more specifically, to a rectifying and step-down power module. Background Art

[0002] Module power supply is a power supply that can be directly mounted on a printed circuit board, and can supply power to application-specific integrated circuits (ASICs), digital signal processors (DSPs), microprocessors, memories, field programmable gate arrays (FPGAs), and other digital or analog loads. Generally, such modules are called point-of-load (POL) power supply systems or point-of-use power supply systems (PUPS). Due to the obvious advantages of the modular structure, module power supplies are widely used in communication fields such as switching equipment, access equipment, mobile communication, microwave communication, optical transmission, routers, as well as automotive electronics and aerospace. However, in the prior art, although module power supplies have excellent load and linear regulation, due to the unstable operation of the circuits inside the existing modules, the load and linear regulation rate are reduced. Therefore, I propose a rectifying and step-down power module. Summary of the Utility Model

[0003] In order to solve the problems raised in the above background art, the utility model provides a rectifying and step-down power module.

[0004] The rectifying and step-down power module provided by the utility model adopts the following technical solutions:

[0005] A rectifying and step-down power module, comprising:

[0006] A ground pin PGND, which is used as a reference ground for adjusting the output voltage. When laying out the PCB, it should be noted that the GND is connected by means of copper plating with vias;

[0007] An output pin SW, connected to an output capacitor COUT;

[0008] An output pin OUT, connected to an output capacitor COUT;

[0009] A bootstrap pin BST, with a bootstrap capacitor built-in between the SW and BST pins to supply power to the internal upper transistor switch drive;

[0010] An enable pin EN, pulling up the EN pin can enable the module. When left floating, the internal 3.3 MΩ resistor pulls the EN pin down to GND, and the module is disabled.

[0011] A feedback pin FB, connecting the FB to an external resistor divider between the output and GND to set the output voltage;

[0012] Signal ground pin AGND. AGND is not internally connected to the system ground. Ensure that AGND is connected to the system ground during PCB layout;

[0013] Power supply voltage pin VIN. The input voltage range of this module is 2.75V to 17V. A 1μF input capacitor is required to decouple the input power rail and is connected using wide PCB traces.

[0014] Preferably, it also includes an internal power output bias pin VCC.

[0015] Preferably, it also includes a soft-start pin SS. Connect a capacitor between SS and GND to set the soft-start time to avoid inrush startup current.

[0016] Preferably, it also includes a power good indicator pin PG. The output of this pin is an open-drain output. When overcurrent protection (OCP), overtemperature protection (OTP), or overvoltage condition (OV) occurs, the pin status will change.

[0017] Preferably, the module has an under-voltage lockout protection function. Under-voltage lockout protection (UVLO) can cause the module to stop working when the supply voltage is insufficient.

[0018] In summary, the present utility model includes the following beneficial technical effects:

[0019] 1. The module of the present utility model uses the constant on-time control mode (COT) to provide fast transient response. The slope compensation function can improve frequency jitter and increase the stability of the module.

[0020] 2. The present utility model realizes the protection of the module through overcurrent protection function, overtemperature protection function, and under-voltage lockout protection function, reducing damage to the module. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the 1V output application circuit in the embodiment of the present utility model;

[0022] Figure 2 is a schematic diagram of the 1.8V output application circuit in the embodiment of the present utility model;

[0023] Figure 3 is a schematic diagram of the typical 3.3V output application circuit in the embodiment of the present utility model;

[0024] Figure 4 is a schematic diagram of the slope compensation function block diagram in the embodiment of the present utility model;

[0025] Figure 5 is a schematic diagram of the continuous conduction mode heavy load working structure in the embodiment of the present utility model;

[0026] Figure 6 It is a schematic diagram of the PG clamping voltage vs. the pull-up current in the embodiment of the present utility model. Detailed implementation manners

[0027] The following further elaborates on the present utility model in conjunction with the attached Figure 1-6 drawings.

[0028] It should be noted that the drawings are schematic and not drawn to scale. For the sake of clarity and convenience in the figures, the relative dimensions and ratios of the parts shown in the figures are exaggerated or reduced in size for illustration, and any dimensions are merely exemplary and not limiting. In addition, the same reference numerals are used for the same structures, elements, or fittings that appear in more than two figures to represent similar features.

[0029] The embodiment of the present utility model discloses a rectifier step-down power supply module. Referring to Figure 1-6 , a rectifier step-down power supply module can achieve a continuous output current of 5 A within a wide input operating voltage range of 2.75 V to 17 V, has excellent load and linear regulation rates, and adopts a synchronous working mode within the output load range to achieve higher efficiency;

[0030] The module adopts a space-saving QFN 24 4 mm x 6 mm package;

[0031] A rectifier step-down power supply module includes:

[0032] A ground pin PGND, which is the reference ground for adjusting the output voltage. Attention should be paid to connecting the GND in a copper-clad manner with vias during PCB layout;

[0033] An internal power output bias pin VCC;

[0034] A VCC regulator. Most of the internal circuits are powered by a 3.5 V internal regulator, which is powered by the VIN input and operates within the full V IN range. When V IN is greater than 3.5 V, the output of the regulator is in a fully regulated state. When V IN drops below 3.5 V, the output of the regulator also drops accordingly. The chip has a built-in 1 μF ceramic decoupling capacitor

[0035] An output pin SW, which is connected to the output capacitor COUT;

[0036] An output pin OUT, which is connected to the output capacitor COUT;

[0037] A bootstrap pin BST. A bootstrap capacitor is built in between the SW and BST pins to supply power to the internal upper transistor switch drive;

[0038] Enable pin EN. Pulling up the EN pin enables the module. When left floating, the internal 3.3 MΩ resistor pulls the EN pin down to GND and the module is disabled;

[0039] EN is the control pin for starting and shutting down the chip: driving EN above 1.23 V turns the chip on, and driving EN below 1 V turns the chip off;

[0040] When floating, the internal 3.3 MΩ resistor pulls the EN pin down to GND. The EN pin can be directly connected to V IN , and it can support an input voltage range of 17 V;

[0041] Feedback pin FB. Connect FB to an external resistor divider between the output and GND to set the output voltage;

[0042] Signal ground pin AGND. AGND is not internally connected to the system ground. Ensure that AGND is connected to the system ground during PCB layout;

[0043] Power supply voltage pin VIN. The input voltage range of this module is 2.75 V to 17 V. A 1 μF input capacitor is required to decouple the input power rail and is connected using wide PCB traces;

[0044] Power good indicator pin PG. The PG pin is the open-drain of the internal MOSFET and should be connected to VCC or other voltage source through a resistor (such as 100 kΩ),

[0045] This MOSFET is turned on after the input voltage is applied so that PG can be pulled to GND before the SS operation. After the FB voltage reaches 90% of the REF voltage, the PG pin is pulled high after a 50 μs delay. When the FB voltage drops to 80% of REF, PG is pulled low,

[0046] When under-voltage lockout protection (UVLO) or over-temperature protection (OTP) occurs, the PG pin will be immediately pulled low; when over-current protection (OC) occurs, after a 0.05 ms delay, the PG pin will be pulled low when VFB drops below 80% of VREF; when over-voltage protection (OV) occurs, after a 0.05 ms delay, the PG pin will be pulled low when VFB rises above 120% of VREF. If VFB drops to 110% of VREF, the PG pin will be pulled high after a 0.05 ms delay;

[0047] If the input power supply cannot power the module, even if PG is connected to an external DC source through a pull-up resistor, PG remains clamped at a low level. The relationship between the PG voltage and the pull-up current is as Figure 6 shown;

[0048] When overcurrent protection (OCP), overtemperature protection (OTP), or overvoltage (OV) occurs, the pin status will change;

[0049] Overcurrent protection (OCP) and short - circuit protection (SCP)

[0050] The module has a valley - current limit control function. The lower switch will monitor the current flowing through it. The upper switch will conduct again after the valley - current limit disappears. At the same time, the output voltage will continue to drop until VFB is lower than the undervoltage (UV) threshold - usually 50% lower than the reference value. Once UV is triggered, the module will enter the hiccup protection mode and automatically restart the chip regularly;

[0051] During overcurrent protection, the device attempts to recover from an overcurrent fault with hiccup protection. The chip will first turn off the output and discharge the soft - start capacitor. After a period of time, it will try to restart the soft - start again. If there is still an overcurrent situation after the soft - start ends, the chip will repeat this cycle of operations until the overcurrent situation disappears and the output voltage steadily rises back to the regulated level. Therefore, this type of overcurrent protection is non - locking protection;

[0052] Overtemperature shutdown protection

[0053] Overtemperature protection can stop the chip from working at too high a temperature. When the chip temperature is higher than 150 °C, the entire module shuts down. When the temperature is lower than the temperature - protection lower limit by 30 °C threshold, the module restarts;

[0054] Under - voltage lock - out protection (UVLO) can stop the module from working when the supply voltage is insufficient. The under - voltage lock - out protection (UVLO) comparator can monitor the output voltage of the internal VCC. The typical rising threshold of the VCC under - voltage lock - out protection (UVLO) is 2.5 V, and its typical falling threshold is 2.3 V. When the input voltage exceeds the rising threshold of the under - voltage lock - out protection (UVLO), power is applied to MAC1606. When the input voltage is lower than the falling threshold voltage of the under - voltage lock - out protection (UVLO), the chip shuts down. This protection is non - locking protection

[0055] The module test conditions are VIN = 5 V, TJ = - 40 °C to + 125 °C, and the typical value test conditions are TJ = + 25 °C:

[0056]

[0057]

[0058]

[0059] For the soft - start pin SS, connect a capacitor between SS and GND to set the soft - start time to avoid inrush current during startup;

[0060] Therefore, the module adopts the soft start (SS) function to ensure a stable power-on output voltage. When the EN pin is set high, the internal current source (6 μA) charges the SS capacitor. At this time, the SS capacitor voltage replaces the REF voltage and is sent to the PWM comparator. The output voltage will slowly rise with the SS voltage. Once the SS voltage rises above VREF, it will continue to rise, and REF is used as the reference value again. At this time, the soft start ends and the chip enters the steady-state operation;

[0061] The SS capacitor value is determined by the following formula:

[0062]

[0063] The module is built-in with a 22 nF SS capacitor.

[0064] If the output capacitor value is large, it is not recommended to set the SS time too short. Otherwise, the current limit is easily triggered during SS.

[0065] The module can also achieve a monotonic linear start in the pre-biased load state;

[0066] If the output is pre-biased with a fixed voltage at startup, the chip will first refresh the BST voltage to charge the BST capacitor and charge the soft start capacitor at the same time. If the BST voltage exceeds its rising threshold voltage and the soft start voltage exceeds the FB voltage of the output sampling, the chip starts to work normally;

[0067] The module provides fast transient response through the constant on-time control mode (COT) and makes the loop easier to stabilize;

[0068] Refer to Figure 4 , the simplified ramp compensation functional block diagram of the module. At the beginning of each cycle, once the feedback voltage (VFB) drops below the reference voltage (VREF), the high-side transistor (HS-FET) conducts, and the conduction duration is jointly determined by the output voltage and the input voltage to ensure that the switching frequency is quite constant within the full input voltage range;

[0069] When the conduction time ends, the high-side transistor turns off until the next cycle starts. When VFB drops below VREF, the high-side transistor conducts again. The converter adjusts the output voltage by repeating this operation. Only when the high-side transistor turns off, the integrated low-side transistor will conduct, which can minimize the conduction loss. If the high-side and low-side transistors conduct simultaneously, a short circuit will be formed between the input and GND. This situation is called shoot-through. To avoid shoot-through, a dead time (DT) needs to be generated internally when the high-side transistor turns off and the low-side transistor conducts or when the low-side transistor turns off and the high-side transistor conducts;

[0070] Using a ceramic output capacitor, the COT control mode with internal slope compensation function can also provide more stable operation. This internal compensation mode can improve frequency jitter without affecting linearity and load regulation ratio;

[0071] Refer to Figure 5 , which shows the continuous conduction mode (CCM). When the output current is large and the inductor current is always higher than zero amperes, it enters the continuous conduction mode (CCM). When VFB is lower than VEAO, the upper transistor will conduct for a fixed time, which is determined by the internal conduction timer. When the upper transistor is turned off, the lower transistor conducts until the next cycle starts;

[0072] Through the above structural design, fast transient response is achieved, and the loop is more easily stabilized;

[0073] If both VIN and EN exceed their respective thresholds, the chip starts. The reference module starts first, generating a stable reference voltage and current, and then enables the internal regulator. The LDO provides a stable power supply for the rest of the circuit;

[0074] The chip will be turned off in three cases: EN is low, VIN is low, and over-temperature shutdown protection. During the shutdown process, the signal loop is blocked first to avoid mis-triggering, and then the internal power supply is pulled down;

[0075] Through the above structural design, the protection of the module is achieved.

[0076] Finally, several points should be noted: First, in the description of the present utility model, it should be noted that unless otherwise specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense, which can be mechanical connection or electrical connection, or the internal connection of two components, and can be directly connected. "Up", "down", "left", "right", etc. are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship may change;

[0077] Second: In the attached drawings of the disclosed embodiments of the present utility model, only the structures related to the disclosed embodiments are involved. Other structures can refer to the usual designs. Without conflict, the same embodiment and different embodiments of the present utility model can be combined with each other;

[0078] Finally: The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A rectifier and step-down power supply module, characterized in that: include: Ground pin PGND, this pin is used to adjust the output voltage reference ground. When laying out the PCB, it should be noted that GND should be connected by copper with vias; The output pin SW is connected to the output capacitor COUT; The output pin OUT is connected to the output capacitor COUT; Bootstrap pin BST, with built-in bootstrap capacitor between SW and BST pins, to power the internal top switch driver; Enable pin EN, pull the EN pin high to enable the module. When it is left floating, the internal 3.3MΩ resistor pulls the EN pin down to GND and the module is disabled; Feedback pin FB, connect FB to an external resistor divider between the output and GND to set the output voltage; Signal ground pin AGND, AGND is not internally connected to the system ground. Make sure to connect AGND to the system ground during PCB layout. Supply voltage pin VIN, the module's input voltage range is 2.75V to 17V, a 1μF input capacitor is required to decouple the input power rail, use wide PCB traces to connect.

2. A rectifier and step-down power supply module according to claim 1, characterized in that: An internal power supply output bias pin VCC is also included.

3. The rectifier and step-down power supply module according to claim 1, characterized in that: A soft-start pin SS is also included. Connect a capacitor between SS and GND to set the soft-start time to avoid startup inrush current.

4. The rectifier and step-down power supply module according to claim 1, characterized in that: It also includes a power normal indication pin PG. The output of this pin is an open-drain output. When over-current protection (OCP), over-temperature protection (OTP) or over-voltage protection (OV) occurs, the pin state will change.

5. The rectifier and step-down power supply module according to claim 1, characterized in that: The module has an under-voltage lockout protection function. The under-voltage lockout protection (UVLO) can stop the module from working when the supply voltage is insufficient.

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