A8660: Wide Input Voltage, Adjustable Output, Synchronous Buck Controller with PWM Frequency Dithering, Synchronization, and NPOR

为了满足供电requirements of automotive, industrial, and consumer applications, the A8660 includes all the control and protection circuitry to produce a robust PWM controller delivering high current.

The A8660 includes PWM frequency dithering, which has been shown to reduce EMI/EMC. A soft recovery feature prevents output voltage overshoot when the converter comes out of a low VIN dropout condition. For high current, low frequency designs (<520 kHz), an external clock can be applied to the SYNCIN pin to shift the PWM harmonics, thus avoiding AM band interference with a tuner or other sensitive electronics.

The A8660 has external compensation so it can be tuned to satisfy various system goals over a wide range of PWM frequencies and external components. It includes adjustable soft start to minimize inrush current. Additionally, it monitors the feedback voltage to provide an open-drain NPOR signal with adjustable delay time.

Extensive protection features of the A8660 include pulse-by pulse current limit, hiccup mode short-circuit protection, BOOT open/short voltage protection, VIN undervoltage lockout, VOUT overvoltage protection, and thermal shutdown. The A8660 is supplied in a low profile 20-pin QFN package (suffix “ES”) with exposed power pad.

• Automotive AEC-Q100 qualified
• Wide operating voltage range: 3.0 to 45 V
• Adjustable output voltage
• PWM frequency dithering reduces EMI/EMC signature and minimizes input filtering
• Programmable base frequency (fOSC): 200 kHz to 2.2 MHz
• For low frequency, high current designs (<520 kHz), applying a clock to SYNCIN will synchronize the PWM frequency to avoid AM band harmonic interference
• Soft recovery from dropout avoids overshoot of VOUT
• External compensation provides flexibility to tune the system for maximum stability or optimum transient response
• Adjustable soft-start time controls inrush current to accommodate a wide range of output capacitance
• Pre-bias startup allows quick, monotonic restart and avoids reset
• High-voltage ENBAT input for ignition/key control
• Logic enable (ENB) input for microcontroller or DSP control
• NPOR open-drain output with adjustable rising delay
• Overvoltage, pulse-by-pulse current limit, hiccup mode short circuit, and thermal protections
• Robust FMEA: pin open/short and component faults