AP1538 Evaluation Module 3A/18V, 300kHz Buck Converter Device Features Description • • • • • • • • • AP1538 is a step-down switching regulator with PWM control. It 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, over current protection and short circuit protection are built-in, 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 minimize external component count. • Input voltage : 3.6V to 18V Output voltage : 0.8V to VCC Output current : up to 3A Duty ratio: 0% to 99% PWM control Oscillation frequency: 300KHz typical Soft-start like, Current limit and Enable function Thermal Shutdown function Built-in internal SW P-channel MOS SOP-8L and SOP-8L-DEP: Available in “Green” Molding Compound (No Br, Sb) Lead-Free Finish / RoHS Compliant With an internal P-channel Power MOS, coupled with the SOP-8L and SOP-8L-DEP mini-packages, these step-down switching regulators can serve as ideal power supply units for portable devices. Since this converter can accommodate an input voltage up to 18V, it is also suitable for the operation via an AC adapter. EVM Features • • • Input voltage : 6V to 18V Output voltage : 5.0V Output current : up to 3A Ordering Information Device Package Code Packaging AP1538SG AP1538SDPG S SDP SOP-8L SOP-8L-DEP AP1538-EVM Rev. 0.1 1 of 5 www.diodes.com EVM Part Number DECEMBER 2008 © Diodes Incorporated AP1538 Evaluation Module 3A/18V, 300kHz Buck Converter Schematic AP1538-EVM Schematic AP1538-EVM Rev. 0.1 2 of 5 www.diodes.com DECEMBER 2008 © Diodes Incorporated AP1538 Evaluation Module 3A/18V, 300kHz Buck Converter PCB Layout Top Layer Layout of AP1538-EVM Bottom Layer Layout of AP1538-EVM AP1538-EVM Rev. 0.1 3 of 5 www.diodes.com DECEMBER 2008 © Diodes Incorporated AP1538 Evaluation Module 3A/18V, 300kHz Buck Converter Bill of Material Bill of Material for AP1538 EVM Ref Count C1 1 C2 1 C3, C6, C9, C10 4 C4 1 C5 1 C7 1 C8 1 R1 1 R2 1 R3 1 R4 1 R5 1 L1 1 D1 1 U1 1 Size 0805 TH 0805 TH 0805 0805 0805 0805 0603 0603 0603 0603 TH SMA SOP8 Mfr STD STD STD STD STD STD STD STD STD STD STD STD Part Number STD STD STD STD STD STD STD STD STD STD STD STD Diodes Diodes B340A AP1538 Description Not populated 470 µF electrolytic capacitor 0.1 µF ceramic capacitor 470 µF electrolytic capacitor Not populated 0.01 µF ceramic capacitor 0.1 µF ceramic capacitor 6.8 kΩ resistor 1.3 kΩ resistor Not populated 20 kΩ resistor 100 kΩ resistor 22 µH inductor 3A/40V Schottky diode 3A/18V 300kHz Buck converter I/O Terminals and Test Points Terminals and Jumpers for AP1538 EVM I/O and Test Points Description Comments VIN, GND VOUT, GND Input and Ground Connect to input power supply Output and Ground OFF Enable jumper Connect to load Open to enable the operation; Place a shunt to disable the device AP1538-EVM Rev. 0.1 4 of 5 www.diodes.com DECEMBER 2008 © Diodes Incorporated AP1538 Evaluation Module 3A/18V, 300kHz Buck Converter Quick Start Guide 1. Leave the Enable jumper open. 2. Connect a +12V power supply between the VIN and GND terminals. Make sure the power supply is turned off. 3. Connect an adjustable current or resistive load to the OUT and GND terminals. 4. Turn on the power supply. Measure the output voltage. Vout should be about 5V. 5. Increase the load current and monitor the output voltage. 6. Vary the input voltage between 6V and 18V and monitor the output voltage. AP1538-EVM Rev. 0.1 5 of 5 www.diodes.com DECEMBER 2008 © Diodes Incorporated