Synchronous:How to distinguish between synchronous and asynchronous? A synchronous switching power supply has two MOSFETs, one is the switching transistor, and the other is the synchronous transistor. When the switching transistor is off, the synchronous transistor turns on to continue the current flow. Synchronous switching power supplies have higher efficiency. A switching power supply that only has one MOSFET and requires an external freewheeling diode is called asynchronous. Due to the higher power consumption of the freewheeling diode, the efficiency is lower.COT:constant-on-time modeConstant On-Time ControlThe on-time is fixed, and the duty cycle is fixed.Some chips adjust the output voltage by controlling a fixed on-time while allowing the off-time to vary. The output voltage is adjusted through the pulse density.This mode has relatively high output ripple noise. When the load changes, the pulse density will vary. Under heavy load, the ripple noise will be greater.
70mΩ/35mΩ Low RON Internal FETs:
The internal resistance of the synchronous or switching transistor.When the transistor is conducting, internal resistance * current = thermal power loss.If the output current remains constant, a larger internal resistance results in greater thermal power loss.Selecting a device with lower internal resistance results in lower thermal power loss, higher efficiency, and better heat dissipation.
COT Control to Achieve Fast Transient Responses:
COT control can achieve fast transient response: The speed of transient response is related to the internal loop. Voltage changes caused by load variations are fed back to the chip, and COT responds by controlling the pulse density to stabilize the voltage.
Power Save Mode at Light Load:
Light load energy-saving mode.As the load decreases, the COT mode can maintain the voltage with fewer pulses, resulting in longer off times for the MOSFET, reducing thermal power loss and achieving energy savings. In contrast, continuous PWM mode will keep switching, which consumes more energy.
Integrated Internal Compensation:
Internal integrated loop compensation.This is a fundamental design of the chip, making external circuit design simpler.
Stable with Low ESR Ceramic Output Capacitors:
Stable low ESR ceramic output capacitors.Place low ESR ceramic output capacitors at the power output terminal.
Over Current Protection with Hiccup Mode:
Overcurrent protection with hiccup mode.When overcurrent occurs, output is paused until the overcurrent condition is resolved, after which normal output resumes. However, this process does not completely turn off the chip.
Thermal Shutdown:
Thermal shutdown protection.
Inrush Current Limit and Soft Start:
Inrush current limit and soft start.During startup, there is a current limit. If power is applied too quickly, the inrush current can be very high, so current limiting and soft start are needed to gradually apply power.
Built-in Input Over Voltage Protection:
Built-in output overvoltage protection.
Junction Temperature:
Junction temperature.
Power Dissipation:
Thermal power loss.