ACE7212E

18V, 2A, High Efficiency Synchronous Step-Down Converter

VER 1.1

7

Functional Description

The ACE7212E is a synchronous buck regulator ICs that integrates the adaptive COT control, top and

bottom switches on the same die to minimize the switching transition loss and conduction loss.

ACE7212E is a wide input range, high-efficiency and high frequency DC-to-DC step-down switching

regulator, capable of delivering up to 2A of output current. It adopts an Adaptive COT control scheme that

enables very fast transient response and provides a very smooth transition when the output varies from

light load to heavy load. It compares the sum of the FB voltage and a ripple voltage that mimics the

voltage due to the output ESR and capacitance. The constant-on-time timer varies with line to achieve

relative constant switching frequency across line.

Light Load Operation

Traditionally, a fixed constant frequency PWM DC-DC regulator always switches even when the output

load is small. When energy is shuffling back and forth through the power MOSFET, power is lost due to

the finite Rdson of the MOSFET and parasitic capacitances. At light load, this loss is prominent and

efficiency is therefore very low. ACE7212E goes into a power save mode during light load, thereby

extending the range of high efficiency operation.

Enable

EN is a digital control pin that turns the ACE7212E on and off. Drive EN High to turn on the regulator,

drive it Low to turn it off. An internal 1MΩ resistor from EN pin to GND allows EN to float to shut down the

chip. Connecting the EN pin through a pull up resistor or shorted EN to IN will automatically turn on the

chip whenever plug in IN.

Over Current Protection and Hiccup

ACE7212E has a cycle-by-cycle over current limit for when the inductor current peak value is over the set

current limit threshold. When the output voltage drop until FB falls below UV threshold (0.6V), the

ACE7212E will enter hiccup mode. It will turn off the chip immediately for 6mS. After that, it will try to

re-starts as normal for 2mS. After 2mS, if FB is still below UV threshold, then the chip enters hiccup mode

again. If FB is higher than UV threshold, it will enter the normal mode.

Over-Temperature Protection

Thermal protection disables the output when the junction temperature rises to approximately 150°C,

allowing the device to cool down. When the junction temperature cools to approximately 110°C, the output

circuitry is again enabled. Depending on power dissipation, thermal resistance, and ambient temperature,

the thermal protection circuit may cycle on and off. This cycling limits regulator dissipation, protecting the

device from damage as a result of overheating.