TPS54140DGQR Supports 42V Input and 1.5A Output

^{September 3, 2025 News — The TPS54140DGQR synchronous buck converter from Texas Instruments (TI) is gaining widespread adoption in industrial power management due to its excellent electrical performance and compact design. According to the technical specifications provided by Mouser Electronics, this device utilizes an efficient thermally enhanced MSOP-10 PowerPAD™ package, supports a wide input voltage range of 3.5V to 42V, and delivers up to 1.5A of continuous output current, providing reliable power solutions for industrial automation, communication infrastructure, and automotive electronics systems.}

^{The TPS54140DGQR integrates a 35mΩ high-side and 60mΩ low-side MOSFET, adopting a current-mode control architecture with a fixed switching frequency of 2.5MHz, enabling the use of miniaturized inductor and capacitor components. According to the Mouser Electronics datasheet, the device automatically enters power-saving mode under light loads, significantly improving light-load efficiency, with a quiescent current of only 116μA. The built-in programmable soft-start circuit effectively suppresses inrush current during startup, providing a smooth power-up sequence.}

^{1.VIN (Pin 1): Power input pin. Supports a wide DC input voltage range of 3.5V to 42V. Requires an external ceramic decoupling capacitor of at least 10μF.}

^{2.EN (Pin 2): Enable control pin. Activates the device when the input voltage exceeds 1.2V (typical) and enters shutdown mode when below 0.5V. This pin must not be left floating.}

^{3.SS/TR (Pin 3): Soft-start/tracking control pin. Programs the soft-start time by connecting an external capacitor to ground, and can also be used for power sequencing tracking.}

^{4.FB (Pin 4): Feedback input pin. Connects to the output voltage divider network. The internal reference voltage is 0.8V ±1%.}

^{5.COMP (Pin 5): Error amplifier compensation node pin. Requires an external RC compensation network to stabilize the control loop.}

^{6.GND (Pins 6, 7, 8): Signal ground pins. Must be connected to the PCB ground plane.}

^{7.SW (Pin 9): Switch node pin. Connects to the external inductor with a maximum voltage rating of 42V. PCB parasitic capacitance at this node should be minimized.}

^{8.PowerPAD™ (Pin 10, bottom thermal pad): Must be soldered to the PCB and connected to GND to provide an effective thermal dissipation path.}

This circuit is a high-frequency, adjustable undervoltage lockout (UVLO) buck switching power supply designed to convert a higher input voltage (such as 12V or 5V bus) into a stable 3.3V output to power digital circuits.

^{1.Core Functions}

^{Voltage Conversion:
Functions as a buck converter to efficiently step down a higher DC input voltage (VIN) to a stable 3.3V DC output voltage (VOUT).}

^{High-Frequency Operation:
Operates at a high switching frequency (likely ranging from hundreds of kHz to over 1MHz).}

^Advantages:

^{Enables the use of smaller inductors and capacitors, reducing the overall size of the power solution.}

^{Delivers faster dynamic response.}

^{Potential Drawbacks:}

^{Increased switching losses.}

^{Requires stricter layout and routing practices.}

^{Adjustable Undervoltage Lockout (UVLO):
A key feature of this design.}

^{Function: Forces the chip to shut down with no output when the input voltage (VIN) is too low.}

^Purpose:

^{Prevents malfunction: Ensures the chip does not operate under insufficient voltage conditions, avoiding abnormal output.}

^{Protects batteries: In battery-powered applications, prevents battery damage from over-discharge.}

^{"Adjustable" Meaning: The UVLO turn-on and turn-off threshold voltages can be customized via an external resistor divider network (typically connected between VIN and the EN (enable) pin or a dedicated UVLO pin), rather than relying on the chip's fixed internal thresholds.}

^{2.Key Components (Typically Included in the Diagram)}

^{1.Switching Regulator IC: The core controller of the circuit. Integrates switching transistors (MOSFETs), drive circuits, error amplifiers, PWM controllers, etc.}

^{2.Inductor (L): An energy storage element that works with capacitors for smooth filtering. It is a key component of the buck topology.}

^{3.Output Capacitor (C_OUT): Smoothens the output current, reduces ripple voltage, and provides transient current to the load.}

^{4.Feedback Network (R_FB1, R_FB2): A resistive voltage divider that samples the output and feeds it back to the chip's FB (feedback) pin. The resistor ratio precisely sets the output voltage (3.3V here).}

^{5.UVLO Setting Resistors (R_UVLO1, R_UVLO2): Another resistive voltage divider, typically sampling the input voltage (V_IN), connected to the chip's EN or UVLO pin. The ratio of this divider determines the minimum input voltage required for system startup.}

^{6.Input Capacitor (C_IN): Provides low-impedance instantaneous current to the chip and reduces input voltage ripple.}

^{7.Bootstrap Capacitor (C_BOOT) (if applicable): Used to drive the high-side switch transistor inside the chip.}

^{3.Design Considerations and Notes}

^{1.Component Selection:}

^{Inductor: The rated current must exceed the maximum load current plus the ripple current, with sufficient margin for the saturation current.}

^{Capacitors: Must meet output voltage ripple and load transient response requirements. Pay attention to their ESR (Equivalent Series Resistance) and rated ripple current.}

^{2.PCB Layout:}

^{The high-frequency characteristics make layout critical.}

^{Key paths (switch node, input capacitor, inductor) should be as short and wide as possible to minimize parasitic inductance and electromagnetic interference (EMI).}

^{The feedback network should be kept away from noise sources (e.g., inductors and switch nodes) and use a star-grounding point connected to the chip's ground pin.}

^{3.UVLO Calculation:}

^{Calculate the values of R_UVLO1 and R_UVLO2 using the formulas provided in the chip datasheet and the start/stop threshold voltages (e.g., V_START(on), V_STOP(off)) to set the desired UVLO thresholds.}

^{Note:
This diagram illustrates a modern, compact, and reliable 3.3V power solution. Its high-frequency characteristics make it suitable for space-constrained applications, while the adjustable UVLO feature enhances reliability and protection in environments with input voltage variations (e.g., battery-powered systems, hot-swap scenarios). To implement this design, it is essential to carefully consult the datasheet of the specific switching regulator IC used and strictly adhere to its recommendations for component selection and PCB layout.}

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