XL1509

Part: XL1509 — HUA XUAN YANG ELECTRONICS CO.,LTD.

Type: Step-down DC/DC Converter

Description: The XL1509 is a monolithic IC designed for a step-down DC/DC converter, capable of driving a 3A load with a wide 4.5V to 40V input voltage range, fixed 150KHz switching frequency, and adjustable output from 1.23V to 37V.

Operating Conditions:

• Supply voltage: 4.5V to 40V
• Operating temperature: -40 to +125 °C
• Fixed switching frequency: 150 KHz
• Output voltage range: 1.23V to 37V (adjustable version)

Absolute Maximum Ratings:

• Max supply voltage: +40 V
• Max continuous current: 3 A
• Max storage temperature: +150 °C

Key Specs:

• Oscillator Frequency: 150 kHz (Typ)
• Current Limit (Peak): 3 A (Min), 4 A (Typ)
• Output Feedback Voltage (XL1509-ADJ): 1.193 V (Min), 1.230 V (Typ), 1.267 V (Max)
• Efficiency (XL1509-5V): 83% (Typ) at V IN = 12V, I LOAD = 3A
• Standby Quiescent Current: 50 μA (Typ), 200 μA (Max)
• ON/OFF pin Logic Input Threshold Voltage (High): 2 V (Min)
• ON/OFF pin Logic Input Threshold Voltage (Low): 0.6 V (Max)
• Thermal Resistance (Junction to ambient): 70 °C/W

Features:

• 3.3V, 5V, 12V and Adjustable Output Version
• Output Adjustable Voltage From 1.23V to 37V
• Fixed 150KHz Switching Frequency
• Voltage Mode Non-synchronous PWM Control
• ON/OFF Shutdown Control Input
• Wide 4.5V to 40V Input Voltage Range
• Output Load Current: 3A
• 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:

• SOP-8 (SOIC-8)

• 3.3V,5V,12V and Adjustable Output Version
• Output Adjustable Voltage From 1.23V to 37V
• Fixed 150KHz Switching Frequency
• Voltage Mode Non-synchronous PWM Control
• ON/OFF Shutdown ControlInput
• Wide 4.5V to 40V Input Voltage Range
• Output Load Current:3A
• Low Power Standby Mode
• Built-in Switching Transistor on Chip

SOP-8(SOIC-8)

SOP-8(SOIC-8)

(Refer to the test circuit,VIN=12V for 3.3V,5V,adjustable version and VIN=24V for the 12V version,ILOAD=0.5A)

The SOP-8(SOIC-8) package needs a heat sink under most conditions. The size of the heatsink depends on the input voltage, the output voltage, the load current and the ambient tem perature. The XL1509 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 XLl509 (SOP-8 package) operating as a buckswitching regulator in an ambient temperature of 25°C(still air). These temperature increments are all approximate and are affected by many factors. Higher ambient temperatures requires more heat sinker.

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 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 increments are all approximate. The increments are affected by a lot of factors. 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, single or double-sided, multi-layer board 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 act as a heat sink taking heat away from the board, or it could add heat to the board.

Fixed Type Circuit