ACE724C

18V 2A Synchronous PFM/PWM Buck Converter

VER 1.5

6

Typical performance characteristics

Functional Descriptions

Loop Operation

The ACE724C is a wide input range, high

‐efficien

of delivering up to 2A of output current, integrated with a 110m  synchronous MOSFET, eliminating the

need for external diode. It uses a PWM current

‐m ode c

between the FB signal and the internal reference voltage. The output of the integrator is then compared to

the sum of a current

‐sense signal and the slope compensation

ramp. This operation generates a PWM

signal that modulates the duty cycle of the power MOSFETs to achieve regulation for output voltage.

Current Limit

There is a cycle

‐by‐cycle current lim it on the high‐side MO

5A (typ). When the current flowing

out of SW exceeds this limit, the high

‐side M

Unlike the traditional method of current limiting by limiting the voltage at the compensation pin, which

usually has large variation due to duty cycle variance, this type of peak current limiting scheme provides a

relatively more accurate limit for output current, thereby lowering the requirements for system design.

Light Load Operation

Traditionally, a fixed current mode constant frequency PWM DC

‐DC regulator alway

itches even

when the output load is small. When energy is shuffling back and forth through the power MOSFETs,

power is lost due to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss

is prominent and efficiency is therefore very low. ACE724C employs a proprietary control scheme that

improves efficiency in this situation by enabling the device into a power save mode during light load,

thereby extending the range of high efficiency operation.

Faster Transient Response