ACT4503YH-T 查看數據表（PDF） - Unspecified
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ACT4503YH-T Datasheet PDF : 55 Pages
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Input Voltage
10-28V
ACT4501 5V/1.0A Smart Phone Car Charger
Device
ACT4501
Standby Power
60mW@12Vin
Output
5V@1.0A
Efficiency
88%@1A , Vin=12V
Topology
Buck
L=30.5mm
W=14.5mm
H=12.8mm
Design Features
Wide input voltage range from 10V to 30V
Transparent input voltage surge 12V-40V-12V
0.5A-1.25A output current limit
4.75V-5.25V during input and load transients
5% output voltage accuracy
125kHz switching frequency
88% efficiency at 12V input
Least external components
Low-cost single layer PCB with very good EMC perform-
ance
Operation and Application
ACT4501 is a step-down DC-DC converter with wide input
voltage range and high efficiency dedicated to 5V/1A smart
phone micro car chargers. The ACT4501 is internally optimized
for good EMC performance and it passed radiated EMI test
even on low-cost single layer PCBs without adding any EMC
components.
Figure 1:
Schematic of Charger
ACT4501 provides constant current (CC) output with patented
Active-CC control technology that eliminate external sense
resistors and the related efficiency loss.
The ACT4501 operates at constant output voltage mode until
it reaches the CC limit set by the ISET resistor. The devices are
available in a SOP-8 package.
Key Component Selection
Higher output inductance reduces the inductor peak-to-peak
current at the expense of higher larger core size and induc-
tance DCR value. Usually, an optimum inductance value is
selected to make its peak-to-peak current 20%-40% of the
maximum load current. The Schottky diode must have current
rating higher than the maximum output current and the re-
verse voltage rating higher than the maximum input voltage.
Output capacitor is selected to keep the peak-to-peak voltage
ripple under required value and also meet the load transient
requirements. Usually, the combination of low ESR capacitors
and tantalum or electrolytic types are used. In this application,
220uF electrolytic capacitor is connected in parallel with a
small 2.2μF ceramic capacitor to achieve small output voltage
ripple and meet the requirements of input and load dynamic
response.
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