1 Features Wide input voltage range:
– TPS5430 : 5.5V to 36V – TPS5431: 5.5V to 23V up to 3-A continuous (4-A peak) output current
110-MΩ integrated mosfet switch enables high efficiency up to 95% Wide output voltage range: adjustable down to
1.22 V with 1.5% initial accuracy
Internal compensation minimizes external parts count Fixed 500 kHz switching frequency Filter size improves line regulation and transient response through input voltage feedforward System is protected against overcurrent limit,
Overvoltage Protection and Thermal Shutdown
-40°C to 125°C operating junction temperature range offers small thermally enhanced 8-pin SO PowerPad 8482 ; package Create custom designs using TPS5430 with Webench® Power Designer
2 Application Consumers: STB, DVD, LCD Display Industrial and Car Audio Power Battery Charger, High Power LED Power
12-V/24-V Distributed Power System Diagram

illustrate
The tps543x is a high output current pwm converter that integrates a low resistance, high side n-channel mosfet. The substrate includes a high-performance voltage error amplifier that provides tight voltage regulation accuracy under transient conditions; an undervoltage lockout circuit that prevents startup until the input voltage reaches 5.5 V; an internally programmed slow-start circuit to limit inrush incoming current; and a voltage feeder to improve the transient response of the circuit. Using the ENA pin, the shutdown supply current is typically reduced to 18µA. Other features include high activation, overcurrent limit, overvoltage protection and thermal shutdown. To reduce design complexity and the number of external components, the TPS543X feedback loop is internally compensated. The TPS5431 is intended to operate on power rails up to 23V. The TPS5430 regulates various power supplies, including the 24V bus.
The TPS543X devices are housed in a thermally enhanced, easy-to-use 8-pin SOIC PowerPad™ package. ti offers evaluation modules and designer software tools to help quickly implement high-performance power supply designs to meet aggressive device development cycles.

Overview
The TPS543X is a 3-A step-down (buck) regulator with an integrated high-side N-channel mosfet. The TPS5431 is intended to operate on power rails up to 23V and the TPS5430 up to 36V . These devices implement constant frequency voltage mode control with voltage feedforward to improve line regulation and line transient response. Internal compensation reduces design complexity and external component count.
The integrated 110 megohm high-side mosfet supports high-efficiency power supply designs capable of delivering 3-A continuous current to the load. The gate drive bias voltage for the integrated high-side MOSFET is provided by a bootstrap capacitor that connects the boot of the bootstrap capacitor to the PH pin. The TPS543X reduces external component count by integrating a bootstrap charge diode.
The default input start-up voltage of the TPS543X is typically 5.3V. ENA pin can be used to disable
The TPS543X reduces supply current to 18 microamps. When the ENA pin is floating, an internal pull-up current source enables operation. The TPS543X includes an internal slow-start circuit that slows the output rise time during startup to reduce inrush current and output voltage overshoot. The minimum output voltage is the internal 1.221 V feedback reference. Output overvoltage transients are minimized by an overvoltage protection (ovp) comparator. When the ovp comparator is activated, the high-side MOSFET is turned off and remains off until the output voltage is less than 112.5% of the desired output voltage.
Inner loop overcurrent protection limits the peak current of the integrated high-side mosfet. For continuous overcurrent fault conditions, the TPS543X will enter Hiccup mode overcurrent limit. Thermal protection prevents the device from overheating.
Functional block diagram

Characteristic Description Oscillator Frequency The internal free running oscillator sets the pwm switching frequency to 500khz. The 500kHz switching frequency allows a smaller output inductance for the same output ripple requirement, resulting in a smaller output inductance.
Voltage Reference The voltage reference system produces an accurate reference signal by adjusting the output of a temperature-stabilized bandgap circuit. During production testing, the bandgap and scaling circuits were trimmed to an output of 1.221 V at room temperature.
Enable (ENA) and Internal Slow Start
The ENA pin provides electrical on/off control of the regulator. Once the ENA pin voltage exceeds the threshold voltage, the regulator begins to operate and the internal slow-start begins to ramp. If the ENA pin voltage is pulled below the threshold voltage, the regulator stops switching and the internal slow-start resets. Grounding or connecting the pin to anything below 0.5 V will disable the regulator and activate shutdown mode. The quiescent current of the TPS543X in shutdown mode is typically 18µA.
The ENA pin has an internal pull-up current source that allows the user to float the ENA pin. If the application needs to control the ENA pin, use an open-drain or open-collector output logic to interface with the pin. To limit startup inrush current, an internal slow-start circuit is used to linearly ramp the reference voltage from 0 V to its final value. The internal slow-start time is typically 8 ms.
Under Voltage Lockout (UVLO)
The TPS543X contains an undervoltage lockout circuit to keep the device disabled when the VIN (input voltage) is below the UVLO startup voltage threshold. During power-up, the internal circuitry remains inactive and the internal slow start is grounded until the vehicle identification number (VIN) exceeds the UVLO start threshold voltage. Once the UVLO startup threshold voltage is reached, the internal slow-start is released and device startup begins. The device works until the vehicle identification number (vin) is below the UVLO stop threshold voltage. Typical hysteresis for uvlo comparators is 330mv.
Boost Capacitor (BOOT)
Connect a 0.01µF low-ESR ceramic capacitor between the pilot pin and the ph pin. This capacitor provides the gate drive voltage for the high side mosfet. X7R or X5R grade dielectrics are recommended because of their stable temperature values.
The output feedback (VSENSE) and the output voltage of the internal compensation regulator are set by feeding back the center point voltage of the external resistor divider network to the VSENSE pin. In steady state operation, the Vsense pin voltage should be equal to the reference voltage of 1.221 V.
The TPS543X implements internal compensation to simplify regulator design. Since the TPS543X uses voltage mode control, a type 3 compensation network is designed on the chip to provide high crossover frequency and high phase margin for good stability. See "Internal Compensation Networks" in the Applications section for details.
Voltage Feedforward Internal voltage feedforward provides constant DC power stage gain even with any change in input voltage. This greatly simplifies stability analysis and improves transient response. Voltage feedforward makes the peak ramp voltage inversely proportional to the input voltage, thus keeping the modulator and power stage gains constant at the feedforward gain, ie.
Feedforward gain ramp Vin
The typical feedforward gain of the TPS543X is 25.
Characterization (continued)
Pulse Width Modulation (PWM) Control The regulator uses a fixed frequency pulse width modulator (pwm) control method. First, an error voltage is generated by comparing the feedback voltage (vsense pin voltage) with a constant voltage reference through a high gain error amplifier and compensation network. Then, the error voltage is compared with the ramp voltage by the pwm comparator. In this way, the error voltage magnitude is converted to a duty cycle pulse width. Finally, the pwm output is input to the gate drive circuit to control the on-time of the high-side mosfet.
Overcurrent Limiting Overcurrent limiting is achieved by sensing the drain-source voltage of the high-side MOSFET. The drain-source voltage is then compared to the voltage level representing the overcurrent threshold limit. If the drain-source voltage exceeds the overcurrent threshold limit, the overcurrent indicator is set to true. The system will ignore the overcurrent indicator for the leading edge blanking time at the beginning of each cycle to avoid any turn-on noise faults.
Once the overcurrent indicator is set to true, the overcurrent limit is triggered. After the propagation delay, the high-side MOSFET is turned off for the rest of the loop. The overcurrent limit mode is called cycle-by-cycle current limit.
Sometimes under severe overload conditions such as short circuit, overcurrent runaway will still occur when cycle-by-cycle current limiting is used. Use the second current limit mode, the Hiccup mode overcurrent limit. During hiccup mode overcurrent limit, the voltage reference is grounded and the high side mosfet is turned off for the hiccup time. Once the hiccup time expires, the regulator restarts under the control of the slow-start circuit.
Over voltage protection
The TPS543X features overvoltage protection (ovp) circuitry to minimize voltage overshoot when recovering from output fault conditions. The ovp circuit includes an overvoltage comparator that compares the vsense pin voltage to a threshold of 112.5% x vref. Once the vSense pin voltage is above the threshold, the high side mosfet will be forced off. When the vSense pin voltage drops below the threshold, the high side mosfet will be enabled again.
thermal shutdown
The TPS543X protects itself from overheating with an internal thermal shutdown circuit. If the junction temperature exceeds the thermal shutdown trip point, the voltage reference is grounded and the high-side MOSFET is turned off. When the junction temperature falls to 14°C below the thermal shutdown trip point, the part is automatically restarted under the control of the slow-start circuit.
Device functional mode operation near the minimum input voltage recommends that the TPS543X operate at input voltages above 5.5 V. A typical Vehicle Identification Number (VIN) uvlo threshold is
5.3V, the device can operate at the input voltage until the UVLO voltage is reached. The UV low voltage device will not switch when the input voltage is lower than the actual value. If en is floated or pulled externally above 1.3v, the tps543x will activate when v(vin) exceeds the uvlo threshold. Enable toggle and initiate a slow start sequence. The TPS543X begins to linearly increase the internal reference voltage from 0V to its final value during the internal slow-start period.
The ENA control operation enables a startup threshold voltage of 1.3 V maximum. When the ENA remains below the 0.5 V minimum stop threshold voltage, the TPS543X is disabled, inhibiting switching even if the VIN is above its UV threshold. In this state, the quiescent current decreases. The device will activate if the ena voltage increases above the maximum activation threshold while v(vin) is above the uvlo threshold. Enable toggle and initiate a slow start sequence. The TPS543X begins to linearly increase the internal reference voltage from 0V to its final value during the internal slow-start period.

Application Information
The TPS543X is a 3-A buck regulator with an integrated high-side mosfet. This device is typically used to convert higher DC voltages to lower DC voltages with a maximum usable output current of 3A. Example applications include: set-top boxes, DVD, LCD and plasma displays, high-power LED power supplies, car audio, battery chargers, and other high-density load regulators for 12-V and 24-V distributed power systems. Use the following design procedure to select component values for the TPS543X. This procedure illustrates the design of a high frequency switching regulator. Alternatively, use the webench software to generate a complete design. Webench software uses an iterative design process and accesses a comprehensive database of components as the design is generated.
To start the design process, some parameters must be determined. Designers need to know the following:
Input Voltage Range Output Voltage Input Ripple Voltage Output Ripple Voltage Output Current Rating Operating Frequency Typical Applications
1 12-V input to 5.0-V output schematic diagram of a typical TPS5430 application. The TPS5430 can deliver up to 3 A of output current at a nominal output voltage of 5 V. For proper thermal performance, the exposed PowerPad™ under the device must be soldered to the printed circuit board.

Detailed Design Procedure The following design procedure can be used to select component values for the TPS5430. This section provides a simplified discussion of the design process.
Custom Designs Using Webench® Tools Click here to create custom designs using the TPS5430 device with Webench® Power Designer.
1. First enter the input input voltage (vin), output voltage (vout) and output current (iout) requirements. 2. Use the optimizer dial to optimize the design of key parameters such as efficiency, footprint and cost.
three. Compare the resulting design with other possible solutions from Texas Instruments.
Webench Power Designer provides a custom schematic and a materials list with real-time pricing and component availability.
In most cases, these operations are available:
Run electrical simulations to view important waveforms and circuit performance Run thermal simulations to understand the thermal performance of the board Export custom schematics and layouts to popular CAD formats Print PDF reports of designs and share designs with colleagues. For more information on the Webench tool, visit /webench.
On-off level
The switching frequency of the TPS5430 is internally set to 500 kHz. The switching frequency cannot be adjusted.
input capacitor
The TPS5430 requires an input decoupling capacitor and, depending on the application, a bulk input capacitor. The recommended value for decoupling capacitor C1 is 10µF. Requires type X5R or X7R high quality ceramic. For some applications, smaller value decoupling capacitors can be used as long as the input voltage and current ripple ratings are not exceeded. The rated voltage must be greater than the maximum input voltage, including ripple.

Wide input voltage range application circuit of TPS5430

10 V–35 V Input to 5 V Output Application Circuit Design Requirements For this design example, use the following parameters as input parameters. The circuit also has a larger output inductance value and a lower closed-loop crossover frequency.

DETAILED DESIGN PROGRAM The design process is similar to the design example given in the 12-V Input to 5.0-V Output section. Detailed design procedure
Wide input voltage range of TPS5431
Application circuit for wide input voltage range of TPS5431.

9 V–21 V Input to 5 V Output Application Circuit Design Requirements For this design example, use the following parameters as input parameters. The circuit also has a larger output inductance value and a lower closed-loop crossover frequency.

DETAILED DESIGN PROGRAM The design process is similar to the design example given in the 12-V Input to 5.0-V Output section. Detailed Design Procedures Circuits Using Ceramic Output Filter Capacitors Application Circuits Using All-Ceramic Capacitors as Input and Output Filters.

Layout Guidelines Connect a low ESR ceramic bypass capacitor to the VIN pin. Care should be taken to minimize the loop area formed by the bypass capacitor connection, the VIN pin, and the TPS543X ground pin. The best way to do this is to extend the top ground area from under the device near the VIN trace and place the bypass capacitor as close to the VIN pin as possible. The minimum recommended bypass capacitor is 4.7µf ceramic and X5R or X7R dielectric.
There should be a ground area on the top layer directly below the IC and an exposed area for connecting to the power board. Connect this ground area to any internal ground plane using vias. Use additional vias on the ground side of the input and output filter capacitors. As shown in the image below, the ground pins should be connected to the PCB ground by connecting to the ground area under the device.
The ph pin should be connected to the output inductor, catch diode, and bootstrap capacitor. Since the ph connection is the switch node, the inductance is very close to the ph pin and the area of the pcb conductors is minimized to prevent excessive capacitive coupling. Catch diodes should also be placed close to the device to minimize output current loop area. Connect the bootstrap capacitor between the phase node and the bootstrap pin as shown. Keep the bootstrap capacitors close to the IC and minimize trace lengths of wires. The component placement and connections shown work well, but other connection routes may also work.
Connect the output filter capacitor between Vout Tracking and GND. It is important to keep the loop formed by the ph pins, lout, cout and gnd as small as possible.
Connect the Vout trace to the Vsense pin using a resistor divider network to set the output voltage. Do not place this trace too close to the ph trace. Due to the size of the IC package and the pin-out of the device, routing under the output capacitor may be required. Alternatively, if the traces under the output capacitors are not required, the routing can be done on an alternate layer.

Mechanical, Packaging, and Ordering Information The following pages include mechanical, packaging, and orderable information. This information is the latest data available for the specified device. This information is subject to change without notice or modification.