LM3670MFX-1.6

LM3670MFX-1.6 Application Field and Working Principle

The LM3670MFX-1.6 is a fixed-frequency, pulse-width modulation controller from Texas Instruments that is used as a DC-DC switching regulator in a wide range of applications which require efficient power conversion. The LM3670MFX-1.6 combines a low RDSon external MOSFET, digitally controlled current setting and external soft-start and watchdog timer, enabling the system designer to integrate high efficiency and reliable operation in a minimal board space design. This feature rich device with integrated switching FETs provides many advantages over conventional discrete switching regulators.

The LM3670MFX-1.6 is designed as a general purpose DC-DC switching regulator that can step down or step up an input voltage with wide line & load regulation and low noise output voltages. It is specifically tailored for applications including server, storage, laptop computer and industrial systems. This high capability regulator is fully featured with power saving and improved noise immunity, making it a perfect solution for the most demanding power applications where high efficiency and high performance are key considerations.

Application Field

The LM3670MFX-1.6 can switch between a wide input voltage range from 2.5V to 12V and output voltage from 0.8V to 5V with as much as 6A of maximum load current. With PWM step-down or step-up regulator, the LM3670MFX-1.6 device can be used to reliable supply power to many applications like smart phones and tablets, processors, FPGAs, ASICs, high-end GPUs, networking and communication equipment, remote monitoring systems, automotive systems, etc. It also finds use in high speed DC-DC buck converters with high efficiency level up to 96%.

Working Principle

The LM3670MFX-1.6 is an innovative switching regulator based on pulse-width modulation (PWM) which works according to the VOUT regulation principle. In a PWM switching converter, the input supply or battery voltage is switched to ground using an external MOSFET switch. That switch is turned ON for a fixed amount of time then OFF for another fixed amount of time, as controlled by the frequency of the PWM signal. When the MOSFET switch is turned ON, the voltage from the input supply is applied to the output capacitors and the output voltage increases. Likewise, when the MOSFET switch is turned OFF, the input supply voltage is removed from the output capacitors and the output voltage begins to decrease.

The LM3670MFX-1.6 maintains the adjusted output voltage through adjusting the duty cycle of the applied PWM signal and by providing external loop compensation. The duty cycle of the PWM signal must be decreased when the output voltage increases and increased when the output voltage decreases. To reduce the duty cycle, the output voltage is sensed and compared against a reference voltage, and the error is then fed to a loop compensation filter. By changing the duty cycle, the MOSFET switch can be turned ON and OFF at any required duty cycle to maintain the output voltage constant.

The maximum current for the LM3670MFX-1.6 is 6A and is obtained by an external MOSFET, thus improving the system efficiency. Additionally, the LM3670MFX-1.6 includes adjustable current setting and external soft start and watchdog timer in the design, which allow the system designer to achieve high efficiency and reliable operation.