Datasheet TSM1012 (STMicroelectronics) - 9
| Fabricante | STMicroelectronics |
| Descripción | Low Consumption Voltage and Current Controller for Battery Chargers and Adaptors |
| Páginas / Página | 14 / 9 — TSM1012. Principle of operation and application hints. 6.3. Start-up and … |
| Formato / tamaño de archivo | PDF / 284 Kb |
| Idioma del documento | Inglés |
TSM1012. Principle of operation and application hints. 6.3. Start-up and short-circuit conditions. 6.4 Voltage. clamp. Equation 5
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TSM1012 Principle of operation and application hints 6.3 Start-up and short-circuit conditions
Under start-up or short-circuit conditions the TSM1012 device is not provided with a high enough supply voltage. This is due to the fact that the chip has its power supply line in common with the power supply line of the system. Therefore, the current limitation can only be ensured by the primary PWM module, which should be chosen accordingly. If the primary current limitation is considered not to be precise enough for the application, then a sufficient supply for the TSM1012 device has to be ensured under any condition. It would then be necessary to add some circuitry to supply the chip with a separate power line. This can be achieved in numerous ways, including an additional winding on the transformer.
6.4 Voltage clamp
Figure 6 shows how to realize a low-cost power supply for the TSM1012 device (with no additional windings). Please pay attention to the fact that in the particular case presented here, this low-cost power supply can reach voltages as high as twice the voltage of the regulated line. Since the absolute maximum rating of the TSM1012 supply voltage is 28 V. In the aim to protect he TSM1012 device against such high voltage values an internal Zener clamp is integrated.
Equation 5
Rlimit = (VCC - Vz) x Ivz
Figure 5. Clamp voltage
7$$ 3MJNJU 7$$ *W[ 7[ 54. 7 ".W DocID10124 Rev 2 9/14 14 Document Outline Figure 1. Pin connections (top view) Table 1. Order codes 1 Pin descriptions Table 2. SO-8 pinout 2 Absolute maximum ratings Table 3. Absolute maximum ratings 3 Operating conditions Table 4. Operating conditions 4 Electrical characteristics Table 5. Electrical characteristics 5 Internal schematics Figure 2. Internal schematic Figure 3. Typical adapter or battery charger application using TSM1012 6 Principle of operation and application hints 6.1 Voltage and current control 6.1.1 Voltage control 6.1.2 Current control Figure 4. Output voltage versus output current 6.2 Compensation 6.3 Start-up and short-circuit conditions 6.4 Voltage clamp Figure 5. Clamp voltage Figure 6. Typical application schematic 7 Package information 7.1 SO-8 package information Figure 7. SO-8 package outline Table 6. SO-8 package mechanical data 8 Revision history Table 7. Document revision history
TSM1012 Principle of operation and application hints 6.3 Start-up and short-circuit conditions
Under start-up or short-circuit conditions the TSM1012 device is not provided with a high enough supply voltage. This is due to the fact that the chip has its power supply line in common with the power supply line of the system. Therefore, the current limitation can only be ensured by the primary PWM module, which should be chosen accordingly. If the primary current limitation is considered not to be precise enough for the application, then a sufficient supply for the TSM1012 device has to be ensured under any condition. It would then be necessary to add some circuitry to supply the chip with a separate power line. This can be achieved in numerous ways, including an additional winding on the transformer.
6.4 Voltage clamp
Figure 6 shows how to realize a low-cost power supply for the TSM1012 device (with no additional windings). Please pay attention to the fact that in the particular case presented here, this low-cost power supply can reach voltages as high as twice the voltage of the regulated line. Since the absolute maximum rating of the TSM1012 supply voltage is 28 V. In the aim to protect he TSM1012 device against such high voltage values an internal Zener clamp is integrated.
Equation 5
Rlimit = (VCC - Vz) x Ivz
Figure 5. Clamp voltage
7$$ 3MJNJU 7$$ *W[ 7[ 54. 7 ".W DocID10124 Rev 2 9/14 14 Document Outline Figure 1. Pin connections (top view) Table 1. Order codes 1 Pin descriptions Table 2. SO-8 pinout 2 Absolute maximum ratings Table 3. Absolute maximum ratings 3 Operating conditions Table 4. Operating conditions 4 Electrical characteristics Table 5. Electrical characteristics 5 Internal schematics Figure 2. Internal schematic Figure 3. Typical adapter or battery charger application using TSM1012 6 Principle of operation and application hints 6.1 Voltage and current control 6.1.1 Voltage control 6.1.2 Current control Figure 4. Output voltage versus output current 6.2 Compensation 6.3 Start-up and short-circuit conditions 6.4 Voltage clamp Figure 5. Clamp voltage Figure 6. Typical application schematic 7 Package information 7.1 SO-8 package information Figure 7. SO-8 package outline Table 6. SO-8 package mechanical data 8 Revision history Table 7. Document revision history