Datasheet TSCR400CX6, TSCR402CX6 (Taiwan Semiconductor) - 6
| 制造商 | Taiwan Semiconductor |
| 描述 | Linear Constant Current Regulated LED Driver |
| 页数 / 页 | 8 / 6 — TSCR400CX6 / TSCR402CX6. APPLICATION INFORMATION. Figure 13: Application … |
| 文件格式/大小 | PDF / 808 Kb |
| 文件语言 | 英语 |
TSCR400CX6 / TSCR402CX6. APPLICATION INFORMATION. Figure 13: Application circuit for Stand along
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TSCR400CX6 / TSCR402CX6
Taiwan Semiconductor
APPLICATION INFORMATION
The TSCR400 & TSCR402 are designed for driving low current LEDs with typical LED currents of 0.1mA to 65mA. They provide a cost-effective way for driving low current LEDs compared with more complex switching regulator solutions. Furthermore, they reduce the PCB board area of the solution as there is no need for external components like inductors, capacitors and switching diodes Figure 13 shows circuit diagram for stand along application an external resistor REXT can be connected to adjust the current. The device comes with an internal resistor (RINT) of typically 6.5kΩ and 44Ω which in the absence of an external resistor, sets an LED current of 0.1mA (typical) for TSCR400 and 20mA (typical) for TSCR402. LED current can be increased to a desired value by choosing an appropriate external resistor, REXT. REXT = VDROP / (IOUT – (VDROP/RINT)) Figure 14 shows boost mode configuration of LED current can be extended to drive high power LEDs The REXT vs ILED graphs should be used to select the appropriate resistor. Choosing a low tolerance REXT will improve the overall accuracy of the current sense formed by the parallel connection of RINT and REXT. REXT = VDROP / (ILED – (VDROP/RINT)) Consideration of the expected linear mode power dissipation must be factored into the design, with respect to the TSCR400 & TSCR402’s thermal resistance. The maximum voltage across the device can be calculated by taking the maximum supply voltage and subtracting the voltage across the LED string. VDEVICE = VS – VLED PD = (VDEVICE × ILED) + (VS × IGND) As the output current of TSCR400 & TSCR402 increases, it is necessary to provide appropriate thermal relief to the device. The power dissipation supported by the device is dependent upon the PCB board material, the copper area and the ambient temperature. The maximum dissipation the device can handle is given by: PD = (TJ(MAX) - TA) / RθJA Vs Supply Vs Supply Vref RINT (Optional) Vref RINT (Optional) REXT REXT REXT VBG VBG Regulator Regulator LED String TSCR400 GND OUT TSCR400 GND OUT I TSCR402 OUT TSCR402 ILED R1 LED String R2
Figure 13: Application circuit for Stand along Figure 14: Application Circuit for Boost mode current source current source with external power transistor
6 Version: B1708
Taiwan Semiconductor
APPLICATION INFORMATION
The TSCR400 & TSCR402 are designed for driving low current LEDs with typical LED currents of 0.1mA to 65mA. They provide a cost-effective way for driving low current LEDs compared with more complex switching regulator solutions. Furthermore, they reduce the PCB board area of the solution as there is no need for external components like inductors, capacitors and switching diodes Figure 13 shows circuit diagram for stand along application an external resistor REXT can be connected to adjust the current. The device comes with an internal resistor (RINT) of typically 6.5kΩ and 44Ω which in the absence of an external resistor, sets an LED current of 0.1mA (typical) for TSCR400 and 20mA (typical) for TSCR402. LED current can be increased to a desired value by choosing an appropriate external resistor, REXT. REXT = VDROP / (IOUT – (VDROP/RINT)) Figure 14 shows boost mode configuration of LED current can be extended to drive high power LEDs The REXT vs ILED graphs should be used to select the appropriate resistor. Choosing a low tolerance REXT will improve the overall accuracy of the current sense formed by the parallel connection of RINT and REXT. REXT = VDROP / (ILED – (VDROP/RINT)) Consideration of the expected linear mode power dissipation must be factored into the design, with respect to the TSCR400 & TSCR402’s thermal resistance. The maximum voltage across the device can be calculated by taking the maximum supply voltage and subtracting the voltage across the LED string. VDEVICE = VS – VLED PD = (VDEVICE × ILED) + (VS × IGND) As the output current of TSCR400 & TSCR402 increases, it is necessary to provide appropriate thermal relief to the device. The power dissipation supported by the device is dependent upon the PCB board material, the copper area and the ambient temperature. The maximum dissipation the device can handle is given by: PD = (TJ(MAX) - TA) / RθJA Vs Supply Vs Supply Vref RINT (Optional) Vref RINT (Optional) REXT REXT REXT VBG VBG Regulator Regulator LED String TSCR400 GND OUT TSCR400 GND OUT I TSCR402 OUT TSCR402 ILED R1 LED String R2
Figure 13: Application circuit for Stand along Figure 14: Application Circuit for Boost mode current source current source with external power transistor
6 Version: B1708