MC1051 Linear LED Power drive
MC1051 is a LED linear constant current driver chip, the current output range from 3 to 2500mA, the current value through the external resistance can constitute a complete LED constant-current driver circuit.The operating voltage range of the chip is 2.5~6V.
MC1051 built-in overheating protection function to avoid damage caused by overheating.
MC1051 has PWM dimming function. The LED current can be adjusted by adding PWM signal at DIM foot.
MC1051 Features and Advantages
■ Working voltage range: 2.5V~60V
■ Output current range value: 3-2500MA
■ PWM dimming: the highest frequency is 100KHZ
■ Enter constant current mode with pressure difference ≥0.4
■ Default base level on power
■ Built-in overheat protection circuit (OTP)
■ Precision of output current ±5%
MC1051 Application
■ Smart LED bulb
■ Lamp power supply
■ Flashlight drive
■ LED backlight
■ LED stage lighting
■ LED headlights
MC1051 The internal block diagram
MC1051 Typical schematic diagram
12V-60V Typical schematic diagram
MC1051 input voltage 12v-60v application circuit diagram
MC1051 input resistance calculation formula：
Vin-5V/1mA（If the margin is large, it shall be calculated as 2mA）=R1(R1 is the VDD resistance to be connected)
12V input R1 resistance setting 7K；
24V input R1 resistance setting 19K；
36V input R1 resistance setting 31K ；
48V input R1 resistance setting 43K ；
54V input R1 resistance setting 49K ；
60V input R1 resistance setting 55K ；
VDD capacitance setting range 1uf-4.7uf (the capacity is determined according to the ripple of PCB power supply voltage)
Efficiency calculation method: output voltage ÷ input voltage = efficiency
Loss calculation method: input voltage - output voltage = voltage difference * current = loss power
The input voltage ripple is less than 1%, and there is no need to increase the input capacitance
12V-60V Typical schematic diagram（Output series diode）
The input voltage of the output series diode mc1051 is higher than the output voltage by 0.4V and enters the constant current mode. At the end of 0.4V, the output current gradually decreases, but does not affect the normal operation; When the input voltage is 0.4V higher than the output voltage, the output voltage can be increased by means of output series diodes to share the chip voltage drop; Mc1051 PWM port adopts the default low-level mode, and there is no need to increase the pull-down resistance for dimming. The internal processing interference circuit is added, and the PWM is not easy to be disturbed by the outside, resulting in light flashing, flickering, light shaking and other phenomena; The PWM dimming frequency of mc1051 is 3 ~ 100kHz (meet the dimming without stroboscopic and anhydrous ripple), and the linearity is the best. MCU is not required to compensate the dimming performance.
MC1051 Schematic diagram of non dimming application (PWM and VDD can be used for non dimming application)
MC1051 Schematic diagram of chip 5V input
VDD can be directly powered from the bus when the input voltage is less than 5V, and the minimum working voltage is 2.5V
Application schematic diagram of MC1051 with increased input capacitance
The input ripple (fluctuation) of MC1051 is large, and the input capacitance is increased to improve the working stability
MC1051 dual channel dimming and color matching application circuit
Common positive output can be used for dual channel or multi-channel applications；The VDD resistance and capacitance of MC1051 can be shared, but the device cannot be too far away from the chip, and the resistance needs to be reduced and the capacitance needs to be increased accordingly；
MC1051 dual chip and multi chip parallel applications
MC1051 can drive high power by using multiple chips in parallel. The VDD resistance and capacitance of MC1051 can be shared, but the device cannot be too far away from the chip, and the resistance needs to be reduced and the capacitance needs to be increased accordingly;
MC1051O Odering information
Pin definition of MC1051
MC1051 Application guidelines working principle
MC1051 is a low static current, PWM dimming function of LED linear step-down constant current driver.Constant current control of output current is realized by sampling CS pin voltage.
The VDD operating voltage range of MC1051 power supply pin is 2.5V to 5.5V. When the power supply voltage is higher than 5.5V, the chip operating voltage clamp is set at 5.7V through internal LDO. The excess VDD current is consumed through LDO to
meet the high voltage, large current and constant current LED drive.
MC1051 has built-in overheating protection function. When the ambient temperature is too high, the chip will enter into the
overheating protection state, and the output current of LED will gradually decrease as the temperature rises, which can effectively protect the chip (when the IC internal temperature reaches 130 ° C, the output current will drop by 1%mV/ ° C, and the output will be turned off when the IC internal temperature reaches 150 ° C).
MC1051 Output current setting:
MC1051 sampling voltage Vcs typical value is 200mV. LED current is determined by the following formula:
Where RCS is the sampling resistance.In order to ensure the constant current accuracy of the output current, the RCS should use high-precision resistors of less than 1%.
MC1051 PWM dimmer
MC1051 is equipped with PWM dimming function.By applying PWM signal to DIM pin, the LED current can be changed in the range of 0~100%.When DIM pin is connected to low level, LED output is turned off.When DIM pin is connected to high level, LED output is normal.PWM dimming frequency up to 100KHz
PCB Matters needing attention in layout
In PCB layout, a filter capacitor of about 4.7UF should be added to the VDD pin of MC1051, and the capacitor should be as close to the VDD pin and ground as possible.On the one hand, the filter capacitor can reduce the voltage spike of VDD pin when the system is powered up, so as to avoid the damage of IC due to overvoltage; on the other hand, when IC enters the over-temperature protection state, the filter capacitor can avoid the occurrence of large ripple caused by output current fluctuation on the VDD of the power supply.
The line from the sampling resistor RCS to the ground should be as short as possible to reduce the output current error caused by the parasitic resistance of the line.
