TPS54540 4.5-V to 42-V Input, 5 A, Step Down DC-DC Converter with Eco-mode™

1 Features

• High Efficiency at Light Loads with Pulse Skipping Eco-mode™
• 92-mΩ High-Side MOSFET
• 146 μA Operating Quiescent Current and
  2 μA Shutdown Current
• 100 kHz to 2.5 MHz Fixed Switching Frequency
• Synchronizes to External Clock
• Low Dropout at Light Loads with Integrated BOOT Recharge FET
• Adjustable UVLO Voltage and Hysteresis
• 0.8 V 1% Internal Voltage Reference
• 8-Terminal HSOP with PowerPAD™ Package
• –40°C to 150°C T_J Operating Range
• Create a Custom Design using the TPS54540 with the WEBENCH® Power Designer

2 Applications

• Industrial Automation and Motor Control
• Vehicle Accessories: GPS, Entertainment
• USB Dedicated Charging Ports and Battery Chargers
• 12 V and 24 V Industrial, Automotive and Communications Power Systems

3 Description

The TPS54540 is a 42 V, 5 A, step down regulator with an integrated high side MOSFET. The device survives load dump pulses up to 45V per ISO 7637. Current mode control provides simple external compensation and flexible component selection. A low ripple pulse skip mode reduces the no load supply current to 146 μA. Shutdown supply current is reduced to 2 μA when the enable pin is pulled low.

Undervoltage lockout is internally set at 4.3 V but can be increased using the enable pin. The output voltage start up ramp is internally controlled to provide a controlled start up and eliminate overshoot.

A wide switching frequency range allows either efficiency or external component size to be optimized. Output current is limited cycle-by-cycle. Frequency foldback and thermal shutdown protects internal and external components during an overload condition.

The TPS54540 is available in an 8-terminal thermally enhanced HSOP PowerPAD™ package.

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Simplified Schematic

Efficiency vs Load Current

4 Revision History

Changes from A Revision (March 2014) to B Revision

• Added the WEBENCH information in the Features, Detailed Design Procedure, and Device Support sectionsGo
• Changed the Handling Ratings table To ESD Ratings tableGo
• Changed V_IN MIN Value From: 4.5 V To: V_O + V_DO, and added Note 1 in the Recommended Operating ConditionsGo
• Deleted last graph: "5 V Start and Stop Voltage" from the Typical CharacteristicsGo
• Updated text and added Equation 1 in the Low Dropout Operation and Bootstrap Voltage (BOOT) Go
• Deleted text: "The start and stop voltage for a typical 5 V..." from the Low Dropout Operation and Bootstrap Voltage (BOOT) sectionGo
• Changed Equation 7 and Equation 8. Go
• Changed Equation 27 Go
• Added new section: Minimum V_INGo
• Deleted 2 graphs named "Low Dropout Operation" from the Application Curves section Go

Changes from * Revision (May 2013) to A Revision

• Added Device Information table, Recommended Operating Conditions table, Pin Configuration and Functions section, Handling Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section.Go
• Changed the Electrical Characteristics Conditions From: VIN = 4.5 to 60 V To: VIN = 4.5 to 42 VGo
• Changed the Operating: nonswitching supply current TEST CONDITIONS From: FB = 0.83 V To: FB = 0.9 VGo
• Changed RT/CLK high threshold MAX value From: 1.7 V To: 2 V Go
• Changed the title of graph "5 V Start and Stop Voltage" to include a link to the Low Dropout Operation section. Go
• Changed the FBD, removed the Logic block and Shutdown signal from the OV comparatorGo
• Changed VF = Forward Drop of the Catch Diode To: V_D = Forward Drop of the Catch Diode Go
• Deleted value TSW = 1 / Fsw from the list following Equation 2Go
• Changed VB2SW = VBOOT + VF To: VB2SW = VBOOT + V_DGo
• Changed VBOOT = (1.41 x V_IN - 0.554 - VF / TSW - 1.847 x 10³ x IB2SW) / (1.41 + 1 / Tsw) To: VBOOT = (1.41 x V_IN - 0.554 - V_D x ƒ_SW - 1.847 x 10³ x IB2SW) / (1.41 + ƒ_SW)Go
• Deleted figure: "5V Start/Stop Voltage"Go
• Added a title to Figure 23Go
• Changed the section title From: Selecting the Switching Frequency To: Accurate Current Limit Operation and Maximum Switching FrequencyGo
• Changed text in the Synchronization to RT/CLK terminal section From: "0.5 V and higher than 1.7 V" To: "0.5 V and higher than 2 V" Go
• Changed Equation 33 From: (5.13V² - 5 V²) To: 3.43 V² - 3.3 V²)Go
• Changed Figure 36, VOUT From: 200 mV/div To 100 mV/div Go
• Changed Figure 38 , EN From: 1 V/div To: 2 V/div, VOUT From: 4 V/div To: 2 V/div, and Time = 2 ms/div To: Time = 20 ms/divGo
• Changed Figure 39 , VOUT From: 4 V/div To: 2 V/divGo

5 Pin Configuration and Functions

HSOIC Package

(Top View)