Texas Instruments

TPS7A78 - 120mA Smart Cap-Drop LDO | Texas Instruments

Name: TPS7A78
Brand: Texas Instruments
Price: 0.79 USD
Availability: InStock

MPN: TPS7A78 ✓ Active

In Stock Ships in 1-3 business days

3.3 V, 5 V Vdss 120 mA Id 14-HTSSOP (PWP) Package

From $0.79 USD / Unit

MOQ: 1 |

Price updated: 2026-08-25

Volume Pricing

Qty	Unit Price	Extended
1	$1.25	$1.25
10	$1.12	$11.20
100	$0.98	$98.00
500	$0.87	$435.00
1,000	$0.79	$790.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

Drop-in alternatives for TPS7A78 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

TPS7A7833PWPR

✅ Drop-In

📦 14-HTSSOP (PWP)

Same package, fixed 3.3V output variant

📋 Reference alternative (not in catalog)

TPS7A7850PWPR

✅ Drop-In

📦 14-HTSSOP (PWP)

Same package, fixed 5V output variant

📋 Reference alternative (not in catalog)

ℹ️ 3 cross-package part(s) hidden — different package requires PCB rework and is not a true drop-in replacement. Contact us if you need cross-package suggestions.

TPS7A78 Maximum Ratings & Electrical Characteristics

Output Type	Fixed
Output Voltage Options	3.3 V, 5 V
Maximum Output Current	120 mA
Input Voltage Range (AC)	85 VAC to 265 VAC
Architecture	Capacitance-drop (cap-drop) LDO
Rectification	Active bridge rectifier (internal)
Quiescent Current	[DATA_NEEDED: Quiescent current]
Dropout Voltage	[DATA_NEEDED: Dropout voltage]
Line Regulation	[DATA_NEEDED: Line regulation]
Load Regulation	[DATA_NEEDED: Load regulation]
Operating Temperature Range	[DATA_NEEDED: Operating temperature range]
Package	14-HTSSOP (PWP)
Mounting Type	Surface Mount
RoHS Status	Compliant
MSL Level	[DATA_NEEDED: MSL level]

TPS7A78 Pin Configuration

Pin 1	AC1 — AC input from cap-drop capacitor
Pin 2	AC2 — AC input return
Pin 3	NC — No connect
Pin 4	NC — No connect
Pin 5	GND — Ground
Pin 6	OUT — Regulated output voltage
Pin 7	OUT — Regulated output voltage
Pin 8	NC — No connect
Pin 9	NC — No connect
Pin 10	NC — No connect
Pin 11	NC — No connect
Pin 12	NC — No connect
Pin 13	NC — No connect
Pin 14	NC — No connect
Pin Pad	GND — Exposed thermal pad, connect to ground

Safe Operating Area (SOA) & Thermal Characteristics

No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.

Typical Applications

TPS7A78 is suitable for 6 applications: Smart Meters, Home Automation, IoT Devices, LED Lighting, Appliance Control Boards, Standby Power Supplies.

🏭

Smart Meters

The TPS7A78 provides a compact, non-isolated power supply for smart meters, converting AC mains to a regulated DC rail. Its 120 mA output is sufficient for metering ICs, communication modules, and display drivers. The cap-drop architecture eliminates the need for a bulky transformer, reducing meter size and cost. The device's high efficiency and low standby power help meet energy regulations, and its wide input range (85-265 VAC) ensures operation across global mains voltages.

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🧩

Home Automation

In home automation systems, the TPS7A78 powers smart switches, thermostats, and sensors directly from AC mains. Its small footprint and lack of magnetic components allow for slim wall-mounted designs. The 3.3V or 5V output can directly supply microcontrollers and wireless transceivers. The device's low quiescent current is ideal for always-on devices, and its thermal shutdown protection ensures safe operation in enclosed spaces.

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CC2652R1FRGZR · Texas Instruments TMP117 · Texas Instruments

📱

IoT Devices

The TPS7A78 is ideal for IoT devices that need a compact power supply from AC mains, such as smart plugs, sensors, and gateways. Its 120 mA output can power a microcontroller, sensors, and wireless communication. The cap-drop architecture reduces BOM cost and size compared to transformer-based supplies. The device's wide input range and fixed output options simplify design, and its low standby power helps extend battery life in hybrid-powered systems.

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MSP430FR2433IRGER · Texas Instruments CC3135RNMARG · Texas Instruments

💡

LED Lighting

The TPS7A78 can be used in LED lighting applications to provide a regulated DC supply for LED drivers or control circuits. Its non-isolated design is suitable for retrofit bulbs and fixtures where isolation is not required. The 120 mA output can power LED driver ICs and communication modules for smart lighting. The device's high efficiency reduces heat generation, and its compact package fits into tight spaces.

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TPS92691 · Texas Instruments TMP117 · Texas Instruments

🏭

Appliance Control Boards

In home appliances like washing machines, refrigerators, and air conditioners, the TPS7A78 provides a low-cost power supply for control boards. It converts AC mains to a regulated DC rail for microcontrollers, relays, and user interfaces. The cap-drop architecture is more reliable than resistor-drop supplies and more compact than transformer-based ones. The device's wide input range and protection features ensure robust operation in demanding environments.

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MSP430FR5989IPMR · Texas Instruments DRV8873QPWPRQ1 · Texas Instruments

📺

Standby Power Supplies

The TPS7A78 is well-suited for standby power supplies in TVs, monitors, and other consumer electronics. It provides a small, efficient power source for standby circuits, such as remote control receivers and status LEDs. Its low quiescent current helps meet stringent standby power regulations (e.g., Energy Star). The cap-drop architecture is cost-effective and reliable for low-power standby loads.

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MSP430FR2433IRGER · Texas Instruments TLV743P · Texas Instruments

Recommended Products Summary

What is the TPS7A78?

The TPS7A78 is a 120-mA, smart, capacitance-drop (cap-drop), low-dropout (LDO) linear voltage regulator from Texas Instruments. It uses an external high-voltage capacitor and an internal active bridge rectifier to convert AC mains voltage to a regulated DC output without a magnetic transformer. According to TI's product page, it is designed for non-isolated AC/DC conversion in low-power applications.

What is the output current of TPS7A78?

The TPS7A78 provides a maximum output current of 120 mA. This makes it suitable for low-power loads such as smart meters, IoT sensors, and LED lighting. The output current is limited by the external cap-drop capacitor (CS) value and the input AC voltage, as described in the TI datasheet.

What is the input voltage range of TPS7A78?

The TPS7A78 operates from an AC input voltage range of 85 VAC to 265 VAC, covering worldwide mains voltages. This wide range allows the device to be used in universal power supply designs without modification. The input is applied through an external high-voltage capacitor (CS) that drops the voltage before rectification.

What are the output voltage options for TPS7A78?

The TPS7A78 is available with fixed output voltages of 3.3 V and 5 V. These are common logic and sensor supply voltages, making the device easy to integrate into digital systems. The specific output voltage variant is indicated by the part number suffix, such as TPS7A7833PWPR for 3.3 V output.

How does the TPS7A78 achieve AC/DC conversion without a transformer?

The TPS7A78 uses a capacitance-drop (cap-drop) architecture where an external high-voltage capacitor (CS) is placed in series with the AC line to drop the voltage. The internal active bridge rectifier then converts the reduced AC to DC, and the LDO regulates it to a stable output. This eliminates the need for a bulky magnetic transformer, reducing size and cost.

What is the efficiency of TPS7A78?

The TPS7A78 improves overall efficiency and standby power compared to traditional resistor-drop or transformer-based solutions. By actively clamping the rectified voltage, it minimizes power dissipation. However, the exact efficiency depends on the input voltage, output voltage, and load current. For detailed efficiency curves, refer to the TI datasheet.

What are the typical applications of TPS7A78?

The TPS7A78 is ideal for low-power, non-isolated AC/DC applications such as smart meters, home automation, IoT devices, LED lighting, and appliance control boards. Its compact size and lack of magnetic components make it suitable for space-constrained designs. It is also used in standby power supplies where low quiescent current is critical.

What is the package of TPS7A78?

The TPS7A78 is available in a 14-pin HTSSOP (PWP) package, which is a surface-mount package with an exposed thermal pad. This package provides good thermal performance and is suitable for compact PCB layouts. The PWP package is commonly used for power management ICs.

Is TPS7A78 RoHS compliant?

Yes, the TPS7A78 is RoHS compliant, as indicated on TI's product page and distributor listings. This ensures it meets the European Union's Restriction of Hazardous Substances directive, making it suitable for use in products sold in the EU and other regions with similar regulations.

Where can I buy TPS7A78?

The TPS7A78 is available from authorized distributors such as DigiKey, Mouser, and directly from TI. As of 2026-08-26, DigiKey lists the TPS7A7850PWPR variant in stock. Pricing varies by quantity and distributor, so it is recommended to check current availability and pricing on distributor websites.

What is the price of TPS7A78?

As of 2026-08-26, the TPS7A78 is priced around $1.25 for single-unit quantities, decreasing to approximately $0.79 at 1000 units, based on typical distributor pricing. However, prices may vary between distributors and over time. For the most accurate pricing, check DigiKey, Mouser, or TI's online store.

What is the lead time for TPS7A78?

The lead time for TPS7A78 depends on the distributor and current stock levels. As of 2026-08-26, DigiKey shows the TPS7A7850PWPR as 'ships today', indicating immediate availability. For other variants, lead times may vary from a few days to several weeks. Check distributor websites for real-time lead time information.

Is TPS7A78 in stock?

As of 2026-08-26, the TPS7A7850PWPR variant is in stock at DigiKey and ships today. Other variants may have different stock levels. It is recommended to check Mouser and TI's website for additional inventory. For high-volume orders, contact distributors for lead time and availability.

What is the difference between TPS7A78 and TPS7A4701?

The TPS7A78 is a cap-drop AC/DC linear regulator designed for non-isolated mains-powered applications, while the TPS7A4701 is a low-noise LDO for DC input applications. The TPS7A78 operates from AC input (85-265 VAC) and provides up to 120 mA, whereas the TPS7A4701 operates from DC input (3-35 V) and provides up to 1 A. They serve different purposes and are not drop-in replacements.

Can TPS7A78 be used for IoT devices?

Yes, the TPS7A78 is well-suited for IoT devices that require a compact, low-cost power supply from AC mains. Its 120 mA output is sufficient for many IoT sensors, microcontrollers, and wireless modules. The non-isolated design is acceptable for applications where isolation is not required, and the low standby power helps meet energy efficiency regulations.

Engineering reference data for TPS7A78 — comparison, design guidance, and compliance information.

Selection Guide

Choose the TPS7A78 when you need a compact, non-isolated AC/DC power supply for low-power applications (up to 120 mA) and want to avoid magnetic components. It is ideal for smart meters, IoT devices, and appliance control boards. If you need higher output current or isolation, consider a flyback controller like UCC28730-Q1, but be prepared for a larger footprint and more complex design. For applications requiring a specific output voltage, select the appropriate variant (TPS7A7833PWPR for 3.3V, TPS7A7850PWPR for 5V). The TPS7A78 is not a drop-in replacement for DC-input LDOs like TPS7A4701.

Comparison with Alternatives

Parameter	This Product	TPS7A7833PWPR	TPS7A7850PWPR	UCC28730-Q1
Package	14-HTSSOP (PWP)	14-HTSSOP (PWP)	14-HTSSOP (PWP)	SOT-23-6
Brand	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments
Output Current	120 mA	120 mA	120 mA	[DATA_NEEDED]
Input Voltage (AC)	85-265 VAC	85-265 VAC	85-265 VAC	[DATA_NEEDED]
Output Voltage	3.3V or 5V (fixed)	3.3V fixed	5V fixed	[DATA_NEEDED]
Architecture	Cap-drop LDO	Cap-drop LDO	Cap-drop LDO	Flyback controller
Isolation	Non-isolated	Non-isolated	Non-isolated	Isolated (with transformer)
Pin Compatibility	Reference	Pin-compatible	Pin-compatible	Not pin-compatible

Key Differentiators

Capacitance-drop architecture eliminates magnetic transformer (vs UCC28730-Q1)
Integrated active bridge rectifier (vs LNK304)
Fixed output options (3.3V/5V) simplify design (vs UCC28880)

Design Notes

The TPS7A78 uses a capacitance-drop architecture, so the external capacitor (CS) must be selected carefully. The capacitor value determines the maximum output current and must be rated for the full AC mains voltage (e.g., 400V for 265VAC). Use a Class X2 safety capacitor for reliability. Refer to the TI datasheet for the formula to calculate CS based on load current and input voltage.

For optimal thermal performance, solder the exposed thermal pad (GND) to a large copper area on the PCB. The HTSSOP package has a thermal resistance that depends on the PCB copper area. Provide at least 1 square inch of copper on the top layer and use thermal vias to connect to inner and bottom layers. This is especially important for high input voltage and load conditions.

Do not operate the TPS7A78 without a proper cap-drop capacitor (CS) connected, as this will cause excessive voltage at the input and may damage the device. Also, ensure the output capacitor is placed close to the OUT pins to maintain stability. The device is non-isolated, so the output is referenced to the AC mains; ensure proper insulation and safety measures in the final product.