External protection circuit for ballast chip 3520D
By designing an external protection circuit for ballast chip 3520D, the problem of protection time uncertainty of ballast when the lamp is abnormal is solved, the damage of field effect transistors and ballasts is prevented, and the reliability of the equipment is improved.
Patent Information
- Application Number
- CN202420858014.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-23
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-04-23
AI Technical Summary
The protection time of the ballast chip 3520D when the lamp is abnormal is uncertain, which may lead to damage to the field effect transistor, thereby damaging the ballast.
An external protection circuit is designed, including an abnormal protection circuit and a lamp driving control circuit. Through a specific combination of resistors, diodes and transistors, it detects and responds to changes in current during abnormal conditions to prevent overloading of the ballast chip.
It effectively prevents damage to the ballast chip when the lamp is abnormal, and improves the reliability and service life of the ballast.
Smart Images
Figure CN222827388U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to an abnormal state protection circuit, in particular to an external protection circuit for a ballast chip 3520D. Background Art
[0002] In the prior art, the abnormal state of the driver designed with the 3520D chip always inevitably leads to a high failure rate. Even if a large-effect transistor is used, a considerable proportion of failures are still inevitable in the abnormal state. The so-called abnormal state generally includes two situations: 1. Poor filament contact. The filament has 4 joints and all use plug-in contact. When it is damp or the spring sheet of the plug is loose for a long time, the filament may have poor contact. 2. The abnormal state characteristics of the lamp tube will also appear before the end of its life.
[0003] The protection time of the ballast chip 3520D when the lamp is in an abnormal state varies greatly due to the selected lamp inductance size and the different designs of the lamp inductance heat dissipation thermal resistance. It may be less than 1 second or more than 10 seconds or more. There is a high probability that the field effect transistor will be damaged, that is, the ballast will be damaged.
[0004] To solve the above problems, we made a series of improvements. Utility Model Content
[0005] The purpose of the utility model is to provide an external protection circuit for a ballast chip 3520D to overcome the above-mentioned shortcomings and deficiencies in the prior art.
[0006] An external protection circuit for a ballast chip 3520D, comprising: an abnormal state protection circuit and a lamp drive control circuit, wherein the abnormal state protection circuit is connected to the lamp drive control circuit;
[0007] Wherein, the abnormal state protection circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a first diode, a bidirectional trigger diode, a first transistor and a first capacitor, one end of the first resistor and one end of the second resistor are connected to the positive end of the first diode, the negative end of the first diode and the cathode of the bidirectional trigger diode are connected to one end of the first capacitor, the c pole of the first transistor is connected to one end of the third resistor, the e pole of the first transistor is connected to one end of the fourth resistor, the b pole of the first transistor is connected to the anode of the bidirectional trigger diode, one end of the first capacitor is connected to the negative end of the first diode and the cathode of the bidirectional trigger diode, the other end of the second resistor, the other end of the fourth resistor and the other end of the first capacitor are connected to the ground G of the lamp tube drive control circuit, and the other ends of the first resistor and the third resistor are connected to the lamp tube drive control circuit.
[0008] Furthermore, the lamp driving control circuit includes: a ballast chip 3520D, a first field effect transistor, a second field effect transistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a lamp inductor, a first filament of the lamp, a second filament of the lamp, a second diode, a third diode, a fifth resistor, a sixth resistor, a seventh resistor and a filter capacitor, wherein a pin end of the ballast chip 3520D is connected to the negative end of the second diode, one end of the fifth resistor and the positive end of the filter capacitor, and the ballast chip 3520 The second pin end of D is grounded, the third pin end of the ballast chip 3520D is connected to one end of the sixth resistor, the fourth pin end of the ballast chip 3520D is connected to one end of the second capacitor and the other end of the third resistor of the abnormal protection circuit, the fifth pin end of the ballast chip 3520D is connected to the g pin of the first field effect transistor, the sixth pin end of the ballast chip 3520D is connected to the s pin of the first field effect transistor, the d pin of the second field effect transistor, one end of the seventh resistor, one end of the fourth capacitor, and one end of the third capacitor, and the ballast The seventh pin end of the ballast chip 3520D is connected to the g pin of the second field effect transistor, the eighth pin end of the ballast chip 3520D is connected to the other end of the third capacitor, the other end of the fourth capacitor is connected to the fourth pin of the lamp inductor, the other end of the fifth capacitor is connected to the positive electrode of the second diode and the negative electrode of the third diode, the other end of the second capacitor is grounded G, the negative electrode of the filter capacitor is grounded G, the other end of the sixth resistor is grounded G, the s pin of the second field effect transistor is grounded G, the positive electrode of the third diode is grounded G, one end of the sixth capacitor is connected to one end of the first filament of the lamp tube, the other end of the sixth capacitor is connected to one end of the second filament of the lamp tube, the other end of the second filament of the lamp tube is grounded G, the other end of the first filament of the lamp tube is connected to the first pin of the lamp inductor, the other end of the first filament of the lamp tube is connected to the other end of the first resistor, the other end of the fifth resistor and the s pin of the first field effect transistor are connected to the external power supply V+, the first pin of the lamp inductor is connected to the first resistor, and the fourth pin end of the ballast chip 3520D is connected to the third resistor.
[0009] Beneficial effects of the utility model:
[0010] Compared with the conventional technology, the utility model can prevent the field effect transistor switch tube from being damaged when the ballast chip is in an abnormal state by adding a protection circuit, that is, prevent the ballast from being damaged. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a structural schematic diagram of the utility model.
[0012] Reference numerals:
[0013] The abnormal state protection circuit 100 , a first resistor 110 , a second resistor 120 , a third resistor 130 , a fourth resistor 140 , a first diode 150 , a bidirectional trigger diode 160 , a first transistor 170 and a first capacitor 180 .
[0014] Lamp tube driving control circuit 200, ballast chip 3520D210, first field effect transistor 220, second field effect transistor 230, second capacitor 240, third capacitor 250, fourth capacitor 260, fifth capacitor 270, sixth capacitor 280, lamp inductor 290, first filament 2100 of the lamp tube, second filament 2200 of the lamp tube, second diode 2300, third diode 2400, fifth resistor 2500, sixth resistor 2600, seventh resistor 2700 and filter capacitor 2800. DETAILED DESCRIPTION
[0015] The following is a further description of the present invention in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.
[0016] Example 1
[0017] Figure 1 It is a structural schematic diagram of the utility model.
[0018] like Figure 1 As shown, an external protection circuit for a ballast chip 3520D includes: an abnormal state protection circuit 100 and a lamp drive control circuit 200, wherein the abnormal state protection circuit 100 is connected to the lamp drive control circuit 200;
[0019] The abnormal state protection circuit 100 includes: a first resistor 110, a second resistor 120, a third resistor 130, a fourth resistor 140, a first diode 150, a bidirectional trigger diode 160, a first transistor 170 and a first capacitor 180, one end of the first resistor 110 and one end of the second resistor 120 are connected to the positive end of the first diode 150, the negative end of the first diode 150 and the cathode of the bidirectional trigger diode 160 are connected to one end of the first capacitor 180, and the first transistor 170 is connected to one end of the third resistor 130. The e pole of the first transistor 170 is connected to one end of the fourth resistor 140, the b pole of the first transistor 170 is connected to the anode of the bidirectional trigger diode 160, one end of the first capacitor 180 is connected to the negative end of the first diode 150 and the cathode of the bidirectional trigger diode 160, the other end of the second resistor 120, the other end of the fourth resistor 140 and the other end of the first capacitor 180 are connected to the ground G of the lamp tube driving control circuit 200, and the other ends of the first resistor 110 and the third resistor 130 are connected to the lamp tube driving control circuit 200.
[0020] The lamp driving control circuit 200 includes: a ballast chip 3520D210, a first field effect transistor 220, a second field effect transistor 230, a second capacitor 240, a third capacitor 250, a fourth capacitor 260, a fifth capacitor 270, a sixth capacitor 280, a lamp inductor 290, a first filament 2100 of the lamp, a second filament 2200 of the lamp, a second diode 2300, a third diode 2400, a fifth resistor 2500, a sixth resistor 2600, a seventh resistor 2700 and a filter capacitor 2800, wherein a pin end of the ballast chip 3520D210 is connected to a negative end of the second diode 2300 and one end of the fifth resistor 2500. and the positive terminal of the filter capacitor 2800, the second pin of the ballast chip 3520D210 is grounded, the third pin of the ballast chip 3520D210 is connected to one end of the sixth resistor 2600, the fourth pin of the ballast chip 3520D210 is connected to one end of the second capacitor 240 and the other end of the third resistor 130 of the abnormal state protection circuit 100, the fifth pin of the ballast chip 3520D210 is connected to the pin of the first field effect transistor 220g, the sixth pin of the ballast chip 3520D210 is connected to the pin of the first field effect transistor 220s, the pin of the second field effect transistor 230d, one end of the seventh resistor 2700, and the fourth capacitor 260 , one end of the third capacitor 250 is connected, the seventh pin end of the ballast chip 3520D210 is connected to the g pin of the second field effect transistor 230, the eighth pin end of the ballast chip 3520D210 is connected to the other end of the third capacitor 250, the other end of the fourth capacitor 260 is connected to the fourth pin of the lamp inductor 290, the other end of the fifth capacitor 270 is connected to the anode of the second diode 2300 and the cathode of the third diode 2400, the other end of the second capacitor 240 is grounded G, the cathode of the filter capacitor 2800 is grounded G, the other end of the sixth resistor 2600 is grounded G, the s pin of the second field effect transistor 230 is grounded G, the third diode 24 The positive pole of 00 is connected to the ground G, one end of the sixth capacitor 280 is connected to one end of the first filament 2100 of the lamp tube, the other end of the sixth capacitor 280 is connected to one end of the second filament 2200 of the lamp tube, the other end of the second filament 2200 of the lamp tube is connected to the ground G, the other end of the first filament 2100 of the lamp tube is connected to a pin of the lamp inductor 290, the other end of the first filament 2100 of the lamp tube is connected to the other end of the first resistor 110, the other end of the fifth resistor 2500 and the s pin of the first field effect transistor 220 are connected to the external power supply V+, a pin of the lamp inductor 290 is connected to the first resistor 110, and the four pin end of the ballast chip 3520D210 is connected to the third resistor 130.
[0021] The principle of the utility model is: first, the characteristics of the circuit state in the abnormal state. In the abnormal state, since the circuit is in a state close to the resonance of L [lamp inductor 290] and C [sixth capacitor 280], the effective value of the current flowing through the first field effect transistor 220, the second field effect transistor 230, the sixth capacitor 280, and the lamp inductor 290 (hereinafter referred to as: loop current) is several times that of the normal working state. In normal operation, the inductance impedance XL of the general lamp inductor 290 is much larger than the lamp resistance Rlamp, taking XL / Rlamp=4, the current in normal operation=(V+) / (√Rlamp^2+XL^2)=(4*V+) / [(√17)*XL], while in the abnormal state close to resonance, / Rlamp does not exist, and the filament resistance Rfilament is so small as to be negligible relative to Rlamp, the capacitance impedance XC of the sixth capacitor 280 is close to XL and in the opposite direction, taking -3 / 4XL, the loop current in the abnormal state=(V+) / (XL+XC)=(4*V+) / XL, the current in the abnormal state / the current in normal operation=√17>4 times.
[0022] Secondly, the problem and analysis of the built-in protection circuit. The abnormal state protection function of the ballast chip 3520D does not directly protect the circuit according to the size of the loop current, but only checks the degree of distortion of the current flowing through the second field effect transistor 230. When the peak current is 5 times greater than its average value (this ratio is less than 2 during normal operation), the first field effect transistor 220 and the second field effect transistor 230 are protected. It is inferred that the design logic of the abnormal state protection function of the ballast chip 3520D should be that once the LC resonance state is entered, the current flowing through the lamp inductor 290 increases several times, the lamp inductor 290 quickly saturates, the saturated inductance impedance XL of the lamp inductor 290 is extremely small, the peak current in the loop is extremely large, and the loop current is seriously distorted. Correspondingly, its peak current also increases rapidly at the same time. If the peak value of the current in the second field effect transistor 230 reaches 5 times its average value, the abnormal state protection function of the ballast chip 3520D is activated, and the circuit stops working, thereby protecting the first field effect transistor 220 and the second field effect transistor 230. However, the actual situation is not so. If the size of the lamp inductor 290 is increased to increase reliability, or the heat dissipation of the lamp inductor 290 is improved, the time for the lamp inductor 290 to enter saturation will be significantly increased. Before the lamp inductor 290 enters the saturation state, the loop current distortion is not serious, and the peak value of the loop current in the second field effect transistor 230 cannot reach 5 times its average value, and the built-in protection circuit will not work. However, during this period, the effective value of the current has reached several times that of normal operation, and the possibility of burning out the first field effect transistor 220 and the second field effect transistor 230 increases sharply.
[0023] Finally, the operation of the abnormal state protection circuit 100 is described. In the abnormal state, the loop current is several times that in the normal operation, that is, the voltage of the first pin of the lamp inductor 290 to the ground G increases several times. By connecting the first pin of the lamp inductor 290 to the other end of the first resistor 110 in the abnormal state protection circuit 100, the positive and negative peak voltages of the anode of the first diode 150 in the abnormal state increase several times compared with the normal operation. The cathode of the first diode 150 only takes its positive peak value, which hits the bidirectional trigger diode 160 and turns on the first transistor 170 at the same time. The pin c of the first transistor 170 becomes low level, and the third resistor 130 also pulls the level of the fourth pin of the ballast chip 3520D210 down to less than 0.85V, so that the ballast chip 3520D210 stops working and keeps stopping working. By adjusting the values of the first resistor 110, the second resistor 120, the third resistor 130, the fourth resistor 140, the first diode 150, and the bidirectional trigger diode 160, the loop current (design value) at which the ballast chip 3520D210 stops working can be set. The first capacitor 180 is used to find a balance between over-sensitivity and over-slowness in triggering the abnormal state protection circuit 100 to start.
[0024] After the ballast chip 3520D210 stops working, the high level of the first pin of the lamp inductor 290 no longer exists, the cathode of the first diode 150 is 0V, and the bidirectional trigger diode 160 and the first transistor 170 return to the non-conducting state. However, this does not affect the ballast chip 3520D210 to keep stopping working. For the ballast chip 3520D210, as long as the level of its four pins is pulled down to less than 0.85V, it will stop working and remain stopped until the Vcc of one pin is pulled down to below its minimum threshold value, and then it will release and lock its stopped working state. During normal operation and when starting to break down the lamp tube, the level from the first pin of the lamp inductor 290 to the abnormal state protection circuit 100 is designed to reliably prevent the bidirectional trigger diode 160 from being turned on and the first transistor 170 from being turned on.
[0025] Since the utility model does not involve the input parts such as filtering and rectification of the rectifier circuit, this article describes the DC voltage after rectification and smoothing as the external power supply, with the positive end denoted as V+ and the negative end denoted as ground g as the input of the lamp drive control protection circuit. This chip is widely used in the UV lamp sterilization driver of the water purifier.
[0026] Compared with the conventional technology, the utility model can prevent the field effect transistor switch tube from being damaged when the ballast chip is in an abnormal state by adding a protection circuit, that is, prevent the ballast from being damaged.
[0027] The specific implementation modes of the present invention are described above, but the present invention is not limited thereto. The present invention can also have various changes without departing from the purpose of the present invention.
Claims
1. An external protection circuit for a ballast chip 3520D, characterized in that: include: An abnormal state protection circuit (100) and a lamp tube driving control circuit (200), wherein the abnormal state protection circuit (100) is connected to the lamp tube driving control circuit (200); The abnormal state protection circuit (100) comprises: a first resistor (110), a second resistor (120), a third resistor (130), a fourth resistor (140), a first diode (150), a bidirectional trigger diode (160), a first triode (170) and a first capacitor (180); one end of the first resistor (110) and one end of the second resistor (120) are connected to the positive end of the first diode (150); the negative end of the first diode (150) and the cathode of the bidirectional trigger diode (160) are connected to one end of the first capacitor (180); the C pole of the first triode (170) is connected to one end of the third resistor (130); The first transistor (170) is connected to a first end of a lamp driving control circuit (200), the first transistor (170) is connected to an e-pole of one end of a fourth resistor (140), the first transistor (170) is connected to an anode of a bidirectional trigger diode (160), one end of the first capacitor (180) is connected to a negative end of the first diode (150) and a cathode of the bidirectional trigger diode (160), the other end of the second resistor (120), the other end of the fourth resistor (140) and the other end of the first capacitor (180) are connected to a ground G of a lamp driving control circuit (200), and the other ends of the first resistor (110) and the third resistor (130) are connected to the lamp driving control circuit (200).
2. The external protection circuit for the ballast chip 3520D according to claim 1, characterized in that: The lamp tube driving control circuit (200) comprises: a ballast chip 3520D (210), a first field effect transistor (220), a second field effect transistor (230), a second capacitor (240), a third capacitor (250), a fourth capacitor (260), a fifth capacitor (270), a sixth capacitor (280), a lamp inductor (290), a first filament (2100) of the lamp tube, a second filament (2200) of the lamp tube, a second diode (2300), a third diode (2400), a fifth resistor (2500), a sixth resistor (2600), a seventh resistor (2700) and a filter capacitor (2800), wherein a pin end of the ballast chip 3520D (210) is connected to a first pin end of the ballast chip 3520D (210), a third capacitor (250), a sixth capacitor (250), a fourth capacitor (260), a fifth capacitor (270), a sixth capacitor (280), a lamp inductor (290), a first filament (2100) of the lamp tube, a second filament (2200) of the lamp tube, a second diode (2300), a third diode (2400), a fifth resistor (2500), a sixth resistor (2600), a seventh resistor (2700) and a filter capacitor (2800). The negative end of the second diode (2300), one end of the fifth resistor (2500) and the positive end of the filter capacitor (2800) are connected, the second pin end of the ballast chip 3520D (210) is grounded, the third pin end of the ballast chip 3520D (210) is connected to one end of the sixth resistor (2600), the fourth pin end of the ballast chip 3520D (210) is connected to one end of the second capacitor (240) and the other end of the third resistor (130) of the abnormal state protection circuit (100), the fifth pin end of the ballast chip 3520D (210) is connected to the g pin of the first field effect transistor (220), and the sixth pin end of the ballast chip 3520D (210) is connected to the y pin of the first field effect transistor (2 The ballast chip 3520D (210) is connected to the s pin of the second field effect transistor (20), the d pin of the second field effect transistor (230), one end of the seventh resistor (2700), one end of the fourth capacitor (260), and one end of the third capacitor (250); the seventh pin of the ballast chip 3520D (210) is connected to the g pin of the second field effect transistor (230); the eighth pin of the ballast chip 3520D (210) is connected to the other end of the third capacitor (250); the other end of the fourth capacitor (260) is connected to the fourth pin of the lamp inductor (290); the other end of the fifth capacitor (270) is connected to the positive electrode of the second diode (2300) and the negative electrode of the third diode (2400); the other end of the second capacitor (24 ... The first filament (2100) of the lamp tube is connected to the ground G, the negative electrode of the filter capacitor (2800) is connected to the ground G, the other end of the sixth resistor (2600) is connected to the ground G, the s pin of the second field effect transistor (230) is connected to the ground G, the positive electrode of the third diode (2400) is connected to the ground G, one end of the sixth capacitor (280) is connected to one end of the first filament (2100) of the lamp tube, the other end of the sixth capacitor (280) is connected to one end of the second filament (2200) of the lamp tube, the other end of the second filament (2200) of the lamp tube is connected to the ground G, the other end of the first filament (2100) of the lamp tube is connected to a pin of the lamp inductor (290), and the other end of the first filament (2100) of the lamp tube is connected to the other end of the first resistor (110).The other end of the fifth resistor (2500) and the s pin of the first field effect transistor (220) are connected to the external power supply V+, a pin of the lamp inductor (290) is connected to the first resistor (110), and a pin 4 of the ballast chip 3520D (210) is connected to the third resistor (130).