Features  Built-in adjustable gain high-sensitivity Hall sensor  High efficiency, using patented control technology to achieve zero-current commutation (ZCS) and zero-magnetic field commutation (ZBS)  Low noise, using SVPWM technology to achieve sinusoidal control of the motor, reducing electromagnetic noise  PWM speed regulation with minimum speed setting  Strong driving capability, RDSON is 0.8Ω, up to 800mA  Wide operating voltage range, 3.5V to 18V  RD alarm and FG counting function optional  Strong protection functions, over-temperature protection, stall protection, H-bridge current limiting protection  Adaptive gain control according to the ambient magnetic field strength  Intelligent soft start, reducing motor starting current and impact on the power supply  Configurable speed curve  ESD (HBM) 6000V Applications  Single-coil DC brushless motor  Single-coil DC brushless cooling fan

The CC6421 provides a single-chip solution for PWM speed control of single-coil brushless DC cooling fans. This product is manufactured using an advanced high-voltage BiCMOS process. It integrates a voltage regulator module, Hall element, chopper offset cancellation module, Hall signal linear amplification modulation module, power full-bridge output stage, and digital logic control module. The voltage regulator output module allows the chip to operate in a voltage range of 3.5V to 18V. The PWM port has a built-in 10kΩ pull-up resistor. Since PWM signals are usually provided by open-collector or open-drain outputs, the PWM port does not require an external pull-up resistor. In addition, when the PWM signal line is open, this pull-up resistor ensures that the motor operates at full speed, increasing operational safety. During startup, the CC6421 detects the ambient magnetic field strength and performs adaptive gain adjustment. After the adaptive adjustment is complete, it enters the sinusoidal wave operating state. The CC6421 has an intelligent soft-start function, which can eliminate the peak current during motor startup and improve system reliability. In the startup state, the duty cycle of the output signal gradually increases from 25%, increasing by 5% every 100ms. When the CC6421 completes startup and determines the internal gain, it will transition from the startup state to the sinusoidal current operating state. In this state, the motor speed can be adjusted by inputting PWM signals with different duty cycles through the PWM port. The PWM speed control accuracy is 32 levels. The minimum speed setting function requires two external resistors. This function is very suitable for applications such as computer CPUs and image processors that require a minimum cooling requirement. By configuring resistors with different resistance values between the Vref port and ground, the CC6421 can provide four different slope speed curves. In the sinusoidal current operating state, the output signal of the OUT port is a PWM modulated signal. Due to the characteristics of the coil itself, the high-frequency components in the signal will be filtered out, restoring the sinusoidal current. The sinusoidal current operating mode will greatly improve the fan's operating efficiency and reduce noise. The FG/RD output port provides speed calculation and stall alarm functions. This port integrates short-circuit protection to prevent the chip from being burned out due to short circuits in unexpected situations. The CC6421 has a built-in stall protection function to prevent the fan from burning out the coil and chip due to overheating when encountering mechanical blockage. The CC6421 has a built-in overheat protection function. When the chip temperature exceeds 160℃, the output will be turned off. When the temperature drops to a safe level, the chip automatically resumes operation. The CC6421 uses straight-pin SOP8 and DFN8 3*3 packages, both of which comply with ROHS regulations.