Texas Instruments TPS61161DRVT

Summary of TPS61161DRVT Product

The TPS61161DRVT, produced by Texas Instruments, is a highly integrated LED driver IC featuring a boost (step-up) DC-DC topology. It is specifically optimized for compact display backlighting in portable electronics, supporting white LED strings that require precise, efficient current regulation. Housed in a thermally enhanced 6-pin WSON package (2 mm x 2 mm), the TPS61161DRVT is designed for engineers seeking high efficiency and flexible brightness control within space-constrained designs.

Main Characteristics and Advantages of TPS61161DRVT

The TPS61161DRVT distinguishes itself through a combination of advanced functions vital for modern electronics:

Wide input voltage range: Operates from 2.7 V to 18 V, accommodating a variety of Li-Ion and other supply scenarios.

40 V/0.7 A integrated switch FET: Supports high output voltages, enabling drive for up to 10 white LEDs in series.

High open LED protection: Detects disconnected output strings and clamps the voltage to a safe 38 V, preventing damage to both device and peripheral circuitry.

Precision current regulation: Achieved via a 200 mV feedback reference with ±2% accuracy, ensuring uniform LED brightness.

Flexible dimming control: Supports both PWM analog dimming and EasyScale™ one-wire digital brightness control via a single CTRL pin, allowing seamless integration into more complex user interface or processor-based environments.

Soft start: Prevents excessive inrush currents during power-up, improving system reliability.

Built-in undervoltage lockout and thermal shutdown: Safeguards the device under extreme supply or temperature conditions.

Efficiency up to 90%: Reduces thermal load and extends battery life in portable applications.

Uses of TPS61161DRVT in Electronics

The TPS61161DRVT is ideally suited for the backlighting of medium-sized displays in:

Cellular phones and smartphones with high brightness or sunlight-readable screens

Portable media players (PMPs), GPS receivers, and ultra-mobile computers

Any handheld, battery-powered product requiring compact, bright, and uniform LED backlighting

The TPS61161DRVT’s step-up configuration is particularly advantageous when the input supply is less than the required total forward voltage of the LED string, ensuring operation throughout the battery discharge cycle.

Working Principles and Operating Modes of TPS61161DRVT

The internal architecture of the TPS61161DRVT is based on a current-mode control boost converter operating at a fixed 600 kHz switching frequency, optimized for minimal output ripple and reduced EMI. Brightness control is accomplished via:

PWM dimming mode: A PWM signal at the CTRL pin directly sets the reference voltage—and thus the LED current—providing smooth, audible-noise-free analog dimming. Recommended dimming frequencies are in the range of 5 kHz to 100 kHz.

EasyScale™ digital dimming: A simple, logic-level one-wire protocol over the CTRL pin allows the feedback voltage to be digitally programmed in 32 steps, facilitating precise adjustment and processor-based brightness management.

Open LED protection actively monitors for fault conditions (such as LED string disconnection) and shuts down the switch if necessary, limiting the output to a maximum safe voltage for the LEDs and the output capacitor.

Technical Details and Performance Metrics of TPS61161DRVT

Critical technical specifications for engineering assessment include:

Input voltage: 2.7 V–18 V

Feedback reference voltage: 200 mV ±2%

Maximum output voltage: 38 V (open LED protection threshold)

Maximum switch FET current: 0.7 A

Switching frequency: 600 kHz (fixed)

Soft-start time: ~6.8 ms (with staged FB voltage ramp-up and current limit reduction)

Supply quiescent current: <1 μA in shutdown

Thermal shutdown: 160°C (with 15°C hysteresis)

Package: 2 mm x 2 mm WSON with an exposed thermal pad

Efficiency: Up to 90% depending on output voltage and current

ESD protection: 500 V HBM, 250 V CDM

Designers should consult detailed electrical characteristic tables and application graphs for further analysis of efficiency versus load, current limits versus temperature, and start-up waveforms.

Comprehensive Design Approach Using TPS61161DRVT

The TPS61161DRVT delivers a complete high-efficiency LED driving solution with an emphasis on external component selection:

Inductor: Recommended values are 10 μH to 22 μH, balancing peak current handling, efficiency, and EMI. Sufficient margin for inductor saturation should be ensured under worst-case operating conditions.

Schottky diode: Should have a reverse voltage rating above 38 V and sufficient current capability for the application (e.g., ON Semiconductor MBR0540, ZETEX ZHCS400).

Current sense resistor (R_SET): Sets LED current, calculated as I_LED = V_FB / R_SET, with tight tolerance for accuracy.

Input/output capacitors: Low ESR ceramic types (input: 1–4.7 μF; output: 0.47–10 μF) are preferred for minimal ripple and stability. Output capacitance should account for DC bias derating.

For analog dimming via PWM, the time constant of the feedback RC filter must be optimized for both transient performance and dimming smoothness. High-impedance feedback networks can introduce current setting errors due to FB pin leakage current, especially at low LED currents.

The device includes an on-chip soft start for inrush current mitigation and programmatic control via the EasyScale interface—a master/slave digital interface tolerating a broad range of bit rates.

Application Layout and Heat Dissipation for TPS61161DRVT

As in all high-frequency switching regulators, PCB layout is central to TPS61161DRVT’s performance. Key recommendations include:

Keep the high-current paths—between the VIN, SW, diode, and output capacitor—as short and wide as possible.

Use a continuous ground plane beneath the device to minimize noise coupling.

Position the input and output capacitors close to the relevant pins.

Solder the thermal pad on the WSON package directly to the PCB ground, employing multiple thermal vias to the underlying ground plane for efficient heat sinking.

Restrict the device’s maximum junction temperature to ≤125°C under all conditions, with adequate PCB area for heat dissipation.

Possible Substitute or Comparable Devices for TPS61161DRVT

In applications requiring pin compatibility, automotive qualification, or slightly different open-LED protection thresholds, consider the following:

Texas Instruments TPS61160: Similar to TPS61161DRVT but with a lower open LED protection voltage (26 V), suitable for shorter LED strings (up to 6 series LEDs).

Texas Instruments TPS61161-Q1: Automotive-qualified version (AEC-Q100) for high-reliability designs, with equivalent electrical performance.

Other manufacturers’ high-voltage, PWM-dimmable boost/converter LED drivers—carefully review essential parameters such as input/output voltage range, switching frequency, current capacity, and interface compatibility.

When selecting a replacement, match both electrical and package characteristics and consult the supplier’s product change or discontinuation notices to ensure long-term availability.

Conclusion

The TPS61161DRVT from Texas Instruments provides engineers with a robust, flexible, and highly efficient solution for white LED backlighting in space-constrained, battery-powered designs. Its versatile brightness control options, strong protection features, and compact WSON package facilitate superior integration in modern handheld devices. Proper attention to peripheral component selection, layout, and thermal management will enable designers to fully exploit the capabilities of the TPS61161DRVT, ensuring reliable and uniform display illumination even under demanding conditions. For engineers considering product redesign or procurement, the TPS61161DRVT and its close equivalents continue to represent an optimal choice in the competitive realm of compact LED drivers.