Most modern electronic devices rely on power supplied from utility grids, which can occasionally experience voltage fluctuations. These fluctuations can damage sensitive components, so linear voltage regulators are commonly used to ensure stable power delivery. Among these, Low Dropout Regulators (LDOs) are a popular category. LDOs are designed to maintain regulation even when the output voltage is very close to the input voltage. Thanks to their compact design and ability to operate at low input and output voltages, they are especially well-suited for portable and battery-operated electronics. The TPS7A26 is one such LDO regulator, offering reliable performance in space-constrained and low-power applications.

Overview of the TPS7A26 Voltage Regulator

The TPS7A26 is a low-dropout (LDO) linear voltage regulator featuring a power-good indicator. It is available in both adjustable and fixed output voltage options, making it a versatile solution for a variety of portable electronic applications.

One of its key advantages is its ultra-low quiescent current, which helps maximize battery life in power-sensitive devices. The adjustable version of the TPS7A26 uses external feedback resistors, allowing for flexible output voltage settings and broader application compatibility. Its precise voltage regulation makes it well-suited for powering microcontrollers and other sensitive components.

TPS7A26 Block Diagram and Key Features

Block Diagram of TPS7A26

Block Diagram of TPS7A26

Current Limiting Protection

To safeguard the device under conditions of high transient loads or output short circuits, the TPS7A26 includes an internal current limit function. When this limit is reached, the regulator stops maintaining a stable output voltage, and power dissipation increases, potentially causing the device to heat up.

If the temperature rises beyond a safe threshold, the built-in thermal shutdown feature activates to turn off the regulator. Once the temperature drops to a safe level, the device automatically restarts. Additionally, an independent undervoltage lockout (UVLO) circuit is included to monitor input voltage levels and ensure proper operation.

Operating Modes

The TPS7A26 functions in three main modes:

• Normal Operation – Provides stable voltage regulation.
• Dropout Mode – Occurs when input voltage is close to the output voltage.
• Disabled Mode – The regulator is turned off, minimizing power consumption.

TPS7A26 Circuit Diagram

TPS7A26 Circuit Diagram

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Adjustable Output Configuration with Feedback Resistors

To configure the output voltage on the adjustable version of the TPS7A26, a pair of external feedback resistors (R1 and R2) is required. These resistors form a voltage divider that sets the output voltage based on the following formula:

VOUT = VFB × (1 + R1 / R2)

Recommended Capacitors for Stability

To ensure stable operation, capacitors with low equivalent series resistance (ESR) should be used on both the input and output. When using multilayer ceramic capacitors (MLCCs), it's important to consider that their effective capacitance can vary significantly with changes in voltage and temperature, regardless of the specific dielectric material used.

Input and Output Capacitor Guidelines

If the source impedance exceeds 0.5Ω, it is recommended to use an input capacitor. This helps enhance transient response, reduce input voltage ripple, and improve the power supply rejection ratio (PSRR).

An output capacitor also contributes to better dynamic performance. A value below 50µF is generally sufficient.

Reverse Current Considerations

The TPS7A26 does not include internal protection against reverse current. If there's a possibility of reverse current in the system, an external protection circuit should be added to prevent potential damage.

Pinout and Package Information

Pin Diagram of TPS7A26

The TPS7A26 comes in a 6-pin WSON package. The function of each pin is as follows:

• Pin 1 (OUT): This is the output pin. A capacitor should be connected from OUT to ground for output stability. Place the capacitor as close to the pin as possible.
• Pin 2 (FB): Feedback pin, used only with the adjustable output version. It serves as the input to the internal error amplifier and works with external resistors to set the desired output voltage.
• Pin 3 (PG): Power-Good output pin. This open-drain pin needs to be pulled up to OUT or another voltage rail. It goes high when the output voltage exceeds the PG rising threshold and low when it drops below the PG falling threshold. Connecting PG to ground can help improve thermal performance.
• Pin 4 (EN): Enable pin. When driven above the high-level threshold, the regulator turns on. If the voltage is below the low-level threshold, the regulator enters a low-current shutdown mode. If not used, tie this pin to IN—do not leave it floating.
• Pin 5 (GND): Ground connection.
• Pin 6 (IN): Input power pin. To enhance transient performance and reduce input impedance, place a capacitor between IN and GND close to the device.

TPS7A26 Voltage Regulator: Key Specifications and Application Areas

Specifications

The TPS7A26 offers the following technical characteristics:

• Supports a wide input voltage range from 2.4V to 18V.
• Available in both fixed and adjustable output voltage configurations.
• Maintains ±1% output voltage accuracy across the full temperature range.
• Features a low dropout voltage of 590mV at 500mA load current.
• Integrated active overshoot protection helps suppress output voltage spikes.
• Includes built-in thermal shutdown and overcurrent protection mechanisms.
• External capacitors are required for stable operation.
• Operates reliably within a temperature range of –40°C to +125°C.
• Offered in a compact 6-pin WSON package.
• Features an ultra-low quiescent current of just 2.0µA, ideal for battery-powered designs.
• The fixed output version is available in standard voltages from 1.25V to 5V.
• The adjustable version supports output voltages ranging from 1.25V to 17.4V (based on external resistor configuration).
• No external resistors are needed for the fixed version, minimizing PCB space requirements.
• A 1µF output capacitor is sufficient to ensure stability.
• Both versions deliver 1% regulation accuracy, enhancing precision in output control.
• The enable pin supports up to 18V, allowing flexible control logic.
• The device features internal current limiting for output protection.
• Can be safely stored in environments with temperatures from –65°C to +150°C.

Typical Applications

The TPS7A26 is suitable for a wide range of low-dropout regulation use cases, including:

• Home and building automation systems
• Multicell power banks and battery chargers
• Smart meters and smart grid infrastructure
• Cordless and portable power tools
• Motor control and drive systems
• Consumer appliances (white goods)
• An excellent choice for portable electronics requiring high efficiency and compact footprint

Recommended Alternative: TPS7A11 as a Replacement for TPS7A26

If you're looking for a substitute for the TPS7A26 low-dropout regulator, the TPS7A11 from Texas Instruments is a suitable alternative.

Thanks to its high efficiency and support for low input and output voltages, the TPS7A26 remains a reliable choice for modern systems that demand tight power management and energy efficiency.

The built-in protection features—including thermal shutdown and overcurrent protection—allow the TPS7A26 to perform reliably across a wide range of operating temperatures. For more detailed electrical characteristics, refer to the official Texas Instruments datasheet.

Have you integrated the TPS7A26 into one of your designs? We’d love to hear how you’re using it!

LDO Regulators: Frequently Asked Questions (FAQ)

What are the limitations of using an LDO regulator?

LDO regulators can generate significant heat when handling high current or when there’s a large voltage difference between the input and output. This increases power loss and reduces efficiency. If the heat exceeds the device’s thermal limits, it may shut down to prevent damage, especially in packages with limited thermal dissipation.

What is the purpose of an LDO regulator?

An LDO (Low Dropout) regulator is a linear voltage regulator designed to maintain a steady output voltage even when the input voltage is only slightly higher than the output. For instance, it can convert a 5V input into a stable 3V output, making it useful in low-voltage electronics.

How does an LDO differ from a conventional linear regulator?

The primary difference is the dropout voltage—the minimum difference between input and output voltages required for proper regulation. LDOs require less headroom and can operate with smaller voltage differences. However, they tend to be more complex, slightly costlier, and may introduce more output noise and slower response compared to traditional linear regulators.

When should I choose an LDO over a switching regulator?

LDOs are preferred in applications that demand low noise, such as analog or RF circuits. They're easier to design with and are generally more cost-effective. In many designs, LDOs are placed after a switching regulator to clean up voltage ripple and provide precise, quiet power to sensitive loads.

What are the symptoms of a failing voltage regulator?

Common signs include poor battery charging, dim or flickering lights, unstable system behavior, and malfunctioning electronics. In vehicles or portable systems, a faulty regulator can lead to power instability or system shutdown.

How is dropout voltage calculated?

Dropout voltage is determined by multiplying the pass element resistance by the output current.
Example: If the regulator has an internal resistance of 0.8Ω and supplies 100mA, then:
Dropout Voltage = 0.8Ω × 100mA = 80mV

Which type of voltage regulator offers higher efficiency?

Switching regulators are typically more efficient than LDOs. They alternate between on/off states to minimize power loss, and can boost, buck, or invert voltage levels. This makes them ideal for battery-powered systems where efficiency is critical.

Why add an LDO regulator to a power system?

LDOs are often used to fine-tune voltage after a switching regulator. They reduce output noise, suppress ripple, and provide stable power to components that require precise voltage levels. They are also useful when multiple voltage rails are needed.

What’s the most suitable type of voltage regulator for my project?

• Use switching regulators when efficiency, heat management, or higher voltage conversion flexibility is important.
• Use LDO regulators when your design needs low noise, minimal component count, and operates with a small input-output voltage difference.

What’s the difference between an LDO and a typical linear regulator?

Both are linear regulators, but an LDO regulator can maintain regulation with a much lower input-output voltage difference (dropout voltage). This is due to the use of a different pass element (usually a P-channel or N-channel MOSFET), enabling better performance in low-voltage systems.

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