AP1501-ADJ

Part: AP1501 — Diodes Incorporated

Type: PWM Buck DC/DC Converter

Description: A fully integrated step-down DC/DC converter capable of driving a 3A load, operating at a fixed switching frequency of 150kHz, and offering both fixed (3.3V, 5.0V, 12V) and adjustable output voltage versions.

Operating Conditions:

• Supply voltage: 4.5V to 40V
• Operating junction temperature: -20 to +125 °C
• Output load current: 0.2A to 3A
• Switching frequency: 150 kHz ±15%

Absolute Maximum Ratings:

• Max supply voltage: +45 V
• Max junction temperature: +150 °C
• Storage temperature: -65 to +150 °C

Key Specs:

• Oscillator Frequency: 150 kHz (Typ.)
• Current Limit: 4.0 A (Typ.)
• Feedback Bias Current: 40 nA (Typ.) at VFB = 1.3V
• Quiescent Current: 5 mA (Typ.) at VFB = 12V
• Standby Quiescent Current: 150 μA (Typ.) at ON/OFF Pin = 5V, VIN = 40V
• Adjustable Output Feedback Voltage: 1.23 V (Typ.)
• Efficiency (AP1501-12V): 90% (Typ.) at VIN = 15V, ILOAD = 3A
• Thermal Resistance Junction to Ambient (TO263-5): 37 °C/W (Typ.)

Features:

• Output Voltage: 3.3V, 5V, 12V and Adjustable Output Version
• Adjustable Version Output Voltage Range, 1.23V to 37V
• 150kHz Fixed Switching Frequency
• Voltage Mode Non-Synchronous PWM Control
• Thermal-Shutdown and Current-Limit Protection
• ON/OFF Shutdown Control Input
• Low Power Standby Mode
• Built-In Switching Transistor on Chip

Applications:

• Simple High-Efficiency Step-Down Regulator
• On-Card Switching Regulators
• Positive to Negative Converter

Package:

• TO263-5
• TO220-5

• Output Voltage: 3.3V, 5V, 12V and Adjustable Output Version
• Adjustable Version Output Voltage Range, 1.23V to 37V+4%
• 150kHz +15% Fixed Switching Frequency
• Voltage Mode Non-Synchronous PWM Control
• Thermal-Shutdown and Current-Limit Protection
• ON/OFF Shutdown Control Input
• Operating Voltage can be up to 40V
• Output Load Current: 3A
• Low Power Standby Mode
• Built-In Switching Transistor on Chip
• TO263-5 and TO220-5 Packages
• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
• Halogen- and Antimony-Free. 'Green' Device (Note 3)
• For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative.

https://www.diodes.com/quality/product-definitions/

• Simple High-Efficiency Step-Down Regulator
• On-Card Switching Regulators
• Positive to Negative Converter

Unless otherwise specified, VIN = 12V for 3.3V, 5V, adjustable version and VIN = 24V for the 12V version. ILOAD = 0.5A Specifications with boldface type are for full operating temperature range, the other type are for TJ = +25°C.

AP1501

The AP1501 is available in the 5-pin surface mount TO-263 and TO-220.

Under most conditions, the TO-220 package requires a heat sink. The size of the heat sink depends on the input voltage, the output voltage, the load current, and the ambient temperature. The AP1501 junction temperature rises above ambient temperature for a 3A load and different input and output voltages. The data for these curves was taken with the AP1501 (TO-220 package) operating as a buck switching regulator in an ambient temperature of 25°C (still air). These temperature rise numbers are all approximate and there are many factors that can affect these temperatures. Higher ambient temperatures require more heat sinking.

The TO-263 surface mount package tab is designed to be soldered to the copper on a printed circuit board. The copper and the board are the heat sink for this package and the other heat producing components, such as the catch diode and inductor. The PC board copper area that the package is soldered to should be at least 0.4 in 2 , and ideally should have 2 or more square inches of 2 oz. Additional copper area improves the thermal characteristics, but with copper areas greater than approximately 6 in 2 , only small improvements in heat dissipation are realized. If further thermal improvements are needed, double-sided multilayer PC boards with large copper areas and/or airflow are recommended.

The AP1501 (TO-263 package) junction temperature rises above ambient temperature with a 2A load for various input and output voltages. This data was taken with the circuit operating as a buck switching regulator with all components mounted on a PC board to simulate the junction temperature under actual operating conditions. This curve can be used for a quick check for the approximate junction temperature for various conditions, but be aware that there are many factors that can affect the junction temperature. When load currents higher than 2A are used, doublesided or multilayer PC boards with large copper areas and/or airflow might be needed, especially for high ambient temperatures and high output voltages.

For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board layout. (One exception to this is the output (switch) pin, which should not have large areas of copper.) Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further.

Package thermal resistance and junction temperature rise numbers are all approximate, and there are many factors that will affect these numbers. Some of these factors include board size, shape, thickness, position, location, and even board temperature. Other factors are trace width, total printed circuit copper area, copper thickness, the board being single or double-sided, the board being multilayered, and the amount of solder on the board. The effectiveness of the PC board to dissipate heat also depends on the size, quantity, and spacing of other components on the board, as well as whether the surrounding air is still or moving.

Furthermore, some of these components such as the catch diode will add heat to the PC board, and the heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material, and the DC resistance, it could either add heat to the board or act as a heat sink taking heat away from the board.

AP1501

Please see http://www.diodes.com/package-outlines.html for the latest version.