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AP1533
PWM CONTROL 1.8A STEP-DOWN CONVERTER
Features
• • • • • • • • • • Input voltage: 4V to 23V Output voltage: 0.8V to VCC Output current: 1.8A up to peak 2A Duty ratio: 0% to 99% PWM control Oscillation frequency: 300KHz typ. Soft-start like, Current limit and Enable function Thermal Shutdown function Built-in internal SW P-channel MOS SOP-8L: Available in “Green” Molding Compound (No Br, Sb) Lead Free Finish / RoHS Compliant (Note 1)
General Description
AP1533 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS. AP1533 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0 up to 99%. This converter also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. An enable function, an over current protect function and a short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced from 300KHz to 50KHz. Also, an internal compensation block is built in to minimum external component count. With the addition of an internal P-channel Power MOS, a coil, capacitors, and a diode connected externally, these ICs can function as step-down switching regulators. They serve as ideal power supply units for portable devices when coupled with the SOP-8L mini-package, providing such outstanding features as low current consumption. Since this converter can accommodate an input voltage up to 23V, it is also suitable for the operation via an AC adapter.
Applications
• • • • • • • • PC Motherboard LCD Monitor Graphic Card DVD-Video Player Telecom Equipment ADSL Modem Printer and other Peripheral Equipment Microprocessor core supply
Ordering Information
AP1533 X X X Package S : SOP-8L Lead Free G : Green Packing -U : Tube -13 : Taping
Note:
1. RoHS revision 13.2.2003. Glass and High Temperature Solder Exemptions Applied, see EU Directive Annex Notes 5 and 7.
Device
AP1533S
Note:
Package Packaging Code (Note 2)
S SOP-8L
Tube/Bulk Quantity Part Number Suffix
100 -U
13” Tape and Reel Quantity Part Number Suffix
2500/Tape & Reel -13
2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf.
AP1533 Rev. 1
1 of 8 www.diodes.com
JULY 2007
© Diodes Incorporated
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AP1533
PWM CONTROL 1.8A STEP-DOWN CONVERTER
Pin Assignments
FB 1 EN 2 AP1533 OCSET 3 VCC 4
8 7 6 5
VSS VSS Output Output
Pin Descriptions
Pin Name FB Pin No. 1 Description Feedback pin Power-off pin H: Normal operation (Step-down operation) L: Step-down operation stopped (All circuits deactivated) Add an external resistor to set max output current IC power supply pin Switch Pin. Connect external inductor/diode here. Minimize trace area at this pin t.