Starting circuit suitable for double NPN sealing
By designing a dual NPN co-packaged startup circuit, the problem of high drive loss of a single NPN power transistor is solved, achieving precise power range output and cost savings, thus enhancing product competitiveness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2026-03-06
AI Technical Summary
In the existing technology, the use of a single NPN power transistor requires a large drive base current, resulting in high drive losses. In addition, there are few suppliers of high-voltage Darlington devices and their prices are high, which limits the use of NPN in the high-power range.
The startup circuit employs a dual NPN co-package, which combines the startup unit with the control unit and transformer to achieve the combination of two single NPN power transistors, accurately subdividing the 18-65W power range output, reducing drive losses and saving system costs.
It achieves an output power range of 18-65W, reduces drive losses, saves system costs, and enhances product competitiveness.
Smart Images
Figure CN223978576U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of circuit design technology, specifically a startup circuit suitable for dual NPN co-packages. Background Technology
[0002] With the development of modern fast charging power supply technology, the output voltage and current have gradually increased. From the previous single 5W output, it has become common to 65W, and a few power supply manufacturers have increased it to 120W. Chargers with a power output of less than 65W are the absolute mainstream at present. In the 20W to 65W range, the power transistors driven are all NMOS or gallium nitride, which are at least twice as expensive as power transistors. Furthermore, chargers with a power output of 36W or above mostly use external power cool MOS or encapsulated gallium nitride, which greatly increases the cost of the whole device.
[0003] To reduce system costs, most manufacturers have begun using single NPN power transistors or integrated Darlington transistors. However, using a single NPN power transistor requires a very large drive base current. For example, with IC = 1200mA and a high-voltage NPN amplification factor β = 10, the required current is Ib = 1200 / 10 = 120mA, increasing the average drive current to 40mA. Furthermore, this drive current needs to be continuous. If the system operates at 40V Vcc and the input line voltage is 90V, the drive loss reaches 40*40 = 1.2W. Such high power consumption severely restricts the use of NPN transistors in high-power applications. Using Darlington transistors can increase the output power to 30W, but suppliers of high-voltage 700V Darlington transistors are extremely rare, and their prices are relatively high. There are no Darlington power devices available in large quantities for systems above 30W. Utility Model Content
[0004] In view of this, the purpose of this utility model is to provide a startup circuit suitable for dual NPN co-packaged circuits to solve the above-mentioned technical problems.
[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0006] A startup circuit suitable for dual NPN co-packaged circuits includes a startup unit, a control unit, and a transformer; the startup unit is electrically connected to the control unit and the transformer respectively.
[0007] The startup unit includes a first power transistor NPN1, a second power transistor NPN2, and a third power transistor N1; the control unit is electrically connected to the base of the first power transistor NPN1, the base of the second power transistor NPN2, and the gate of the third power transistor N1, respectively; the collector of the first power transistor NPN1 and the collector of the second power transistor NPN2 are electrically connected to a transformer, respectively.
[0008] Preferably, it also includes a start-up resistor Rs and a diode D2;
[0009] The two ends of the starting resistor Rs are electrically connected to the base and collector of the first power transistor NPN1, respectively. The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2, respectively. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0010] Preferably, it also includes a start-up resistor Rs and a diode D2;
[0011] The two ends of the starting resistor Rs are electrically connected to the collector of the first power transistor NPN1 and the base of the second power transistor NPN2, respectively. The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2, respectively. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0012] Preferably, it also includes a start-up resistor Rs and a diode D2;
[0013] One end of the start-up resistor Rs is connected to the collector of the first power transistor NPN1, and the other end of the start-up resistor Rs serves as a flexible configuration port.
[0014] The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0015] Preferably, it also includes a start-up resistor Rs and a diode D2;
[0016] The two ends of the starting resistor Rs are electrically connected to the collector of the first power transistor NPN1 and the negative terminal of the diode D2, respectively.
[0017] The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0018] Preferably, it also includes a first capacitor C1, the path between the start-up unit and the control unit is electrically connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is grounded.
[0019] Preferably, it also includes a diode D1 and a second capacitor C2; the transformer includes a primary winding Lp and a secondary winding Ls;
[0020] The starting unit is electrically connected to the primary winding Lp, one end of the secondary winding Ls is electrically connected to the positive terminal of diode D1, the negative terminal of diode D1 is electrically connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is electrically connected to the other end of the secondary winding Ls.
[0021] The beneficial effects of this utility model are:
[0022] This invention provides a startup circuit suitable for dual NPN co-packaged transistors, comprising a startup unit, a control unit, and a transformer. The startup unit is electrically connected to both the control unit and the transformer. The startup unit includes a first power transistor NPN1, a second power transistor NPN2, and a third power transistor N1. The control unit is electrically connected to the base of the first power transistor NPN1, the base of the second power transistor NPN2, and the gate of the third power transistor N1. The collectors of the first power transistor NPN1 and the second power transistor NPN2 are electrically connected to the transformer. By combining two single NPN power transistors, a precise 18-65W power range can be achieved, realizing a power range of 18-65W that previously required expensive CoolMOS and Gallium Nitride, significantly reducing system costs and enhancing product competitiveness. Furthermore, using the first power transistor NPN1 to drive the second power transistor NPN2 greatly reduces drive losses, lowering the original 1.2W to 1.2W / 20 = 60mW, achieving the drive current losses required by a power CoolMOS. When heated to 100℃, the equivalent internal resistance is between 0.35 and 1 ohm, reaching the equivalent internal resistance of a power coolmos. Attached Figure Description
[0023] Figure 1 This is a connection diagram of a startup circuit suitable for dual NPN co-packages according to this utility model;
[0024] Figure 2 This is the first circuit connection diagram of the starting unit of this utility model;
[0025] Figure 3 This is a second circuit connection diagram of the starting unit of this utility model;
[0026] Figure 4 This is the third circuit connection diagram of the starting unit of this utility model;
[0027] Figure 5 This is the fourth circuit connection diagram of the starting unit of this utility model. Detailed Implementation
[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:
[0029] This utility model provides a startup circuit suitable for dual NPN co-packaged circuits, including a startup unit, a control unit, a transformer, a first capacitor C1, a diode D1, and a second capacitor C2; the startup unit is electrically connected to the control unit and the transformer respectively; specifically, the Vo terminal of the startup unit is connected to the Vcc terminal of the control unit; the control unit can operate in either primary-side or secondary-side mode, and mainly performs the CC / CV control and startup control required for AC-DC conversion.
[0030] The path between the starting unit and the control unit is electrically connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is grounded. The transformer includes a primary winding Lp and a secondary winding Ls; the Ce terminal of the starting unit is electrically connected to the primary winding Lp, one end of the secondary winding Ls is electrically connected to the positive terminal of diode D1, the negative terminal of diode D1 is electrically connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is electrically connected to the other end of the secondary winding Ls, providing energy output to the load.
[0031] The startup unit includes a first power transistor NPN1, a second power transistor NPN2, and a third power transistor N1; the control unit is electrically connected to the base of the first power transistor NPN1, the base of the second power transistor NPN2, and the gate of the third power transistor N1, respectively; the collector of the first power transistor NPN1 and the collector of the second power transistor NPN2 are electrically connected to a transformer, respectively.
[0032] The output terminal ctr3 of the control unit is connected to B1 of the start-up unit to control the on / off state of the first power transistor NPN1.
[0033] The output terminal ctr2 of the control unit is connected to B3 of the start-up unit, controlling the on / off state of the third power transistor N1.
[0034] The output terminal ctr1 of the control unit is connected to B2 of the starting unit; it controls the on / off state of the second power transistor NPN2.
[0035] The aforementioned startup unit has the following four connection methods, as detailed below:
[0036] The first connection method also includes a start-up resistor Rs and a diode D2. This structure is suitable for the first power transistor NPN1 with an integrated start-up resistor Rs, while the second power transistor NPN2 is a power transistor without an integrated start-up resistor. The first power transistor NPN1 is a BJT type power transistor, and the second power transistor NPN2 is a BJT type power transistor. Their specifications can be flexibly matched to adapt to different power ranges.
[0037] The two ends of the starting resistor Rs are electrically connected to the base and collector of the first power transistor NPN1, respectively. The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2, respectively. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0038] The start-up resistor Rs provides the base drive current for the first power transistor NPN1. The output current, after being amplified by the first power transistor NPN1, provides the base drive current for the second power transistor NPN2. This current, after being amplified by the second power transistor NPN2, charges the external first capacitor C1 through diode D2 and supplies power to the control unit's power supply Vcc terminal.
[0039] The second connection method also includes a start-up resistor Rs and a diode D2. This structure is suitable for power transistors where the first power transistor NPN1 has no integrated start-up resistor Rs, while the second power transistor NPN2 has an integrated start-up resistor Rs. The first power transistor NPN1 is a BJT type power transistor, and the second power transistor NPN2 is a BJT type power transistor. Their specifications can be flexibly matched to adapt to different power ranges.
[0040] The two ends of the starting resistor Rs are electrically connected to the collector of the first power transistor NPN1 and the base of the second power transistor NPN2, respectively. The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2, respectively. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0041] The start-up resistor Rs provides the base drive current for the second power transistor NPN2. This current is amplified by the second power transistor NPN2 and then charges the external first capacitor C1 through diode D2, and supplies power to the control unit's power supply Vcc terminal.
[0042] The third connection method also includes a startup resistor Rs and a diode D2. This structure is suitable for power transistors where the first power transistor NPN1 and the second power transistor NPN2 do not have an integrated startup resistor Rs, requiring a separate external startup resistor Rs. The first power transistor NPN1 is a BJT type power transistor, and the second power transistor NPN2 is a BJT type power transistor. Their specifications can be flexibly matched to adapt to different power ranges.
[0043] One end of the start-up resistor Rs is connected to the collector of the first power transistor NPN1, and the other end of the start-up resistor Rs serves as a flexible configuration port, which the customer can connect according to actual conditions. It charges the external first capacitor C1 and supplies power to the control unit's Vcc terminal.
[0044] The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0045] The fourth connection method also includes a startup resistor Rs and a diode D2. This structure is suitable for power transistors where the first power transistor NPN1 has an integrated startup resistor Rs, but one end of the startup resistor Rs is connected to an external VCC, directly charging the first capacitor C1 through the startup resistor Rs to start the transistor. The second power transistor NPN2 does not have an integrated startup resistor Rs. The first power transistor NPN1 is a BJT type power transistor, and the second power transistor NPN2 is a BJT type power transistor. Their specifications can be flexibly matched to adapt to different power ranges.
[0046] The two ends of the starting resistor Rs are electrically connected to the collector of the first power transistor NPN1 and the negative terminal of the diode D2, respectively.
[0047] The emitter of the first power transistor NPN1 is electrically connected to the base of the second power transistor NPN2. The emitter of the second power transistor NPN2 and the drain of the third power transistor N1 are electrically connected to the anode of the diode D2. The cathode of the diode D2 is electrically connected to the control unit. The source of the third power transistor N1 is grounded.
[0048] One end of the starting resistor Rs is connected to the collector of the first power transistor NPN1 and the collector of the second power transistor NPN1, and connected to the external Ce terminal. The other end of the starting resistor Rs is connected to the Vo terminal of the starting unit, charging the external first capacitor C1 and supplying power to the Vcc terminal of the control unit.
[0049] In summary, this utility model discloses a startup circuit suitable for dual NPN co-packaged transistors, employing different startup unit structures. Specifically, NPN1 and NPN2 without integrated startup resistors utilize a third connection structure; NPN1 with startup resistors and NPN2 without startup resistors utilize a first connection structure; NPN1 without startup resistors combined with NPN2 with startup resistors utilizes a second connection structure; NPN1 integrating a separate startup resistor plus NPN2 without an integrated startup resistor utilizes a fourth connection structure, or NPN2 integrating a separate startup resistor plus NPN1 without an integrated startup resistor utilizes a fourth connection structure. This allows for compatibility with existing mass-produced NPN power transistors from different power manufacturers, enabling the combination of two single NPN power transistors to achieve precise subdivision of the 18-65W power range. This surpasses the 18-65W power range previously achievable with expensive CoolMOS and Gallium Nitride transistors, significantly reducing system costs and enhancing product competitiveness.
[0050] This utility model has been described with reference to the above-described embodiments and accompanying drawings. However, the above embodiments are merely examples for implementing this utility model. It must be noted that the disclosed embodiments do not limit the scope of this utility model. On the contrary, modifications and equivalent provisions included in the spirit and scope of the claims are all included within the scope of this utility model.
Claims
1. A starting circuit suitable for dual NPN hybrid sealing, characterized in that: It comprises a starting unit, a control unit and a transformer; the starting unit is electrically connected with the control unit and the transformer respectively; The starting unit comprises a first power tube NPN1, a second power tube NPN2 and a third power tube N1; the control unit is electrically connected with the base of the first power tube NPN1, the base of the second power tube NPN2 and the gate of the third power tube N1 respectively; the collector of the first power tube NPN1 and the collector of the second power tube NPN2 are electrically connected with the transformer respectively.
2. A starting circuit suitable for dual NPN hybrid sealing according to claim 1, characterized in that: It further comprises a starting resistor Rs and a diode D2; The two ends of the starting resistor Rs are electrically connected with the base and the collector of the first power tube NPN1 respectively; the emitter of the first power tube NPN1 is electrically connected with the base of the second power tube NPN2; the emitter of the second power tube NPN2 and the drain of the third power tube N1 are electrically connected with the positive electrode of the diode D2 respectively; the negative electrode of the diode D2 is electrically connected with the control unit; the source of the third power tube N1 is grounded.
3. A starting circuit suitable for dual NPN hybrid sealing according to claim 1, characterized in that: It further comprises a starting resistor Rs and a diode D2; The two ends of the starting resistor Rs are electrically connected with the collector of the first power tube NPN1 and the base of the second power tube NPN2 respectively; the emitter of the first power tube NPN1 is electrically connected with the base of the second power tube NPN2; the emitter of the second power tube NPN2 and the drain of the third power tube N1 are electrically connected with the positive electrode of the diode D2 respectively; the negative electrode of the diode D2 is electrically connected with the control unit; the source of the third power tube N1 is grounded.
4. The starting circuit according to claim 1, wherein: the starting circuit is adapted for use with a dual NPN hybrid seal. It further comprises a starting resistor Rs and a diode D2; One end of the starting resistor Rs is electrically connected with the collector of the first power tube NPN1; the other end of the starting resistor Rs is used as a flexible configuration port; The emitter of the first power tube NPN1 is electrically connected with the base of the second power tube NPN2; the emitter of the second power tube NPN2 and the drain of the third power tube N1 are electrically connected with the positive electrode of the diode D2 respectively; the negative electrode of the diode D2 is electrically connected with the control unit; the source of the third power tube N1 is grounded.
5. The starting circuit according to claim 1, wherein: the starting circuit is adapted for use with a dual NPN hybrid seal. It further comprises a starting resistor Rs and a diode D2; The two ends of the starting resistor Rs are electrically connected with the collector of the first power tube NPN1 and the negative electrode of the diode D2 respectively; The emitter of the first power tube NPN1 is electrically connected with the base of the second power tube NPN2; the emitter of the second power tube NPN2 and the drain of the third power tube N1 are electrically connected with the positive electrode of the diode D2 respectively; the negative electrode of the diode D2 is electrically connected with the control unit; the source of the third power tube N1 is grounded.
6. A starting circuit suitable for dual NPN hybrid sealing according to claim 1, characterized in that: It further comprises a first capacitor C1; the path between the starting unit and the control unit is electrically connected with one end of the first capacitor C1; the other end of the first capacitor C1 is grounded.
7. A starting circuit suitable for dual NPN hybrid sealing according to claim 1, characterized in that: It further comprises a diode D1 and a second capacitor C2; the transformer comprises a primary winding Lp and a secondary winding Ls; The starting unit is electrically connected with the primary winding Lp, one end of the secondary winding Ls is electrically connected with the anode of a diode D1, the cathode of the diode D1 is electrically connected with one end of a second capacitor C2, and the other end of the second capacitor C2 is electrically connected with the other end of the secondary winding Ls.