A7404
DC-DC CONVERTER/BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
42V INPUT STANDOFF VOLTAGE, 0.4A STEP-DOWN CONVERTER
DETAILED INFORMATION
Functional Descriptions
Loop Operation
The A7404 is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of
delivering up to 0.4A of output current, integrated with a 550mΩ high side MOSFET. It uses a PWM
current-mode control scheme. An error amplifier integrates error 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.
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 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. A7404 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.
REV1.0
- DEC 2015 RELEASED -
- 7 -
AITSEMI [ AiT Semiconductor ]
