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Home Products Integrated Circuits (ICs)PMIC - Voltage Regulators - Linear~~LT1129CST-5#TRPBF~~

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LT1129CST-5#TRPBF - Analog Devices Inc.

Name: Analog Devices Inc. LT1129CST-5#TRPBF
Brand: Analog Devices Inc.
SKU: LT1129CST-5#TRPBF
Availability: InStock
Rating: 5 (7 reviews)

Manufacturer Part Number: LT1129CST-5#TRPBF

Manufacturer: Analog Devices, Inc.

Allelco Part Number: 32D-LT1129CST-5#TRPBF

Warranty: 1 Year Allelco Warranty - Find out more

Stock Status:: 11,015 pcs available, New & Original

Parts Description: IC REG LINEAR 5V 700MA SOT223-3

Package: SOT-223-3

Data sheet: LT1129CST-5#TRP.pdf

Environmental Information
Material Declaration LT1129CST-5#TRPBF.pdf

HTML Datasheet
LT1129(-3.3,-5) Datasheet.pdf

PCN Assembly/Origin
2.73KHz.pdf

Other Related Documents
Tape and Reel Packaging.pdf

RoHs Status: ROHS3 Compliant

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In stock: 11015

Specifications

LT1129CST-5#TRPBF Tech Specifications
Analog Devices Inc. - LT1129CST-5#TRPBF technical specifications, attributes, parameters and parts with similar specifications to Analog Devices Inc. - LT1129CST-5#TRPBF

Product Attribute	Attribute Value
Manufacturer	Analog Devices, Inc.
Voltage Dropout (Max)	0.7V @ 700mA
Voltage - Output (Min/Fixed)	5V
Voltage - Output (Max)	-
Voltage - Input (Max)	30V
Supplier Device Package	SOT-223-3
Series	-
Protection Features	Over Temperature, Reverse Polarity
Package / Case	TO-261-4, TO-261AA
Package	Tape & Reel (TR)
PSRR	64dB (120Hz)

Product Attribute	Attribute Value
Output Type	Fixed
Output Configuration	Positive
Operating Temperature	0°C ~ 125°C
Number of Regulators	1
Mounting Type	Surface Mount
Current - Supply (Max)	90 mA
Current - Quiescent (Iq)	70 µA
Current - Output	700mA
Control Features	Enable
Base Product Number	LT1129

Environmental & Export Classifications

ATTRIBUTE	DESCRIPTION
RoHs Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Unaffected
ECCN	EAR99
HTSUS	8542.39.0001

Parts Introduction

LT1129CST-5#TRPBF (1)

Manufacturer Part Number

LT1129CST-5#TRPBF

Manufacturer

Analog Devices

Introduction

LT1129CST-5#TRPBF is a linear low-dropout (LDO) regulator designed for power management applications. It is packaged in Tape & Reel for efficient assembly in surface mount technology.

Product Features and Performance

Positive fixed output configuration

Single regulator

Maximum input voltage of 30V

Fixed output voltage of 5V

Maximum dropout voltage of 0.7V at 700mA

Output current of 700mA

Quiescent current of 70 µA

Supply current maximum of 90 mA

Power supply rejection ratio (PSRR) of 64dB at 120Hz

Enable control feature

Product Advantages

Low dropout voltage enhances efficiency

High output current capability

Minimal quiescent current aids in power conservation

Over Temperature and Reverse Polarity protection for safety and durability

Key Technical Parameters

Voltage - Input (Max): 30V

Voltage - Output (Min/Fixed): 5V

Voltage Dropout (Max): 0.7V @ 700mA

Current - Output: 700mA

Current - Quiescent (Iq): 70 µA

Current - Supply (Max): 90 mA

PSRR: 64dB (120Hz)

Quality and Safety Features

Protection against Over Temperature and Reverse Polarity

Operating Temperature range of 0°C to 125°C

Compatibility

Mounting Type: Surface Mount

Package / Case: TO-261-4, TO-261AA

Supplier Device Package: SOT-223-3

Application Areas

Suitable for various electronic applications requiring efficient voltage regulation including consumer electronics, telecommunications, and industrial equipment.

Product Lifecycle

The product status is active, ensuring ongoing production and availability. It is not nearing discontinuation.

Several Key Reasons to Choose This Product

Low dropout voltage for enhanced performance in low voltage applications

High output current suitable for demanding applications

Built-in safety features ensure reliability and durability

Wide input voltage range makes it versatile for different electronic setups

Low quiescent current helps in reducing power loss and improving efficiency

Frequently Asked Questions(FAQ)

How does the LT1129CST-5#TRPBF handle thermal performance under continuous 700mA load, and what is the minimum input voltage required to maintain a stable 5V output in a high ambient temperature environment?: Under continuous 700mA output current, the LT1129CST-5#TRPBF exhibits a dropout voltage of up to 0.7V, meaning the input must be at least 5.7V to ensure regulation. In high ambient temperatures—such as 85°C or 100°C—the device’s internal thermal resistance (junction-to-case, approximately 32°C/W) increases power dissipation, which can lead to significant junction temperature rise. For example, with a 6V input, power dissipation reaches 700mA × 1V = 0.7W, resulting in a ΔT of ~22.4°C above case temperature. If the case sits at 85°C, the junction could reach 107.4°C, still within the 125°C maximum rating but reducing available thermal headroom. Proper heatsinking or airflow is essential to prevent throttling due to over-temperature protection.

What are the key differences between the LT1129CST-5#TRPBF and the MIC5209-5.0YS in terms of quiescent current, dropout voltage, and package suitability for space-constrained PCB designs?: The LT1129CST-5#TRPBF offers a quiescent current of 70µA, slightly higher than the MIC5209-5.0YS (typically 50–60µA), but both are suitable for low-power applications. However, the LT1129 has a lower dropout voltage (max 0.7V at 700mA) compared to the MIC5209 (around 0.5V at 300mA), making it more efficient under heavier loads or when input voltage is close to 5V. Package-wise, the LT1129 uses SOT-223-3, which provides better thermal performance than the SC70 or SOT-23 packages commonly used by the MIC5209, enabling higher current handling without external cooling. This makes the LT1129 more appropriate for applications requiring both thermal resilience and moderate current delivery.

Can the LT1129CST-5#TRPBF reliably protect against reverse polarity conditions, and how does its internal protection circuitry compare to discrete diode-based solutions in automotive environments?: Yes, the LT1129CST-5#TRPBF includes integrated reverse polarity protection, allowing it to safely tolerate negative input voltages without damage—critical in automotive systems where accidental battery reversal is common. Unlike discrete Schottky diode solutions that introduce a fixed 0.3–0.5V drop and dissipate power proportional to the load current, the LT1129’s active protection avoids voltage loss and reduces heat generation. For instance, in a 12V system drawing 500mA, a diode would dissipate 1.5W, while the LT1129, if properly biased, handles the fault condition with minimal power loss. This improves efficiency and reliability in harsh environments.

Is the LT1129CST-5#TRPBF suitable for use in battery-powered IoT devices where quiescent current must remain below 100µA and the input voltage may drop as low as 5.5V?: While the LT1129CST-5#TRPBF operates with a quiescent current of 70µA—well within the 100µA limit—its dropout voltage of 0.7V at full load means the minimum usable input is 5.7V. In a deeply discharged Li-ion battery system (e.g., 3.0V nominal, dropping to 3.3V during discharge), the LT1129 cannot regulate a 5V output. Therefore, it is not ideal for directly stepping up from sub-5.7V sources. For such applications, a switching regulator like the LTC3649 would be more efficient. However, if the system maintains an auxiliary supply or uses a charge pump to boost the rail above 5.7V, the LT1129 becomes viable due to its ultra-low Iq and robust protection features.

How does the PSRR of the LT1129CST-5#TRPBF perform at high frequencies, and what implications does this have for noise-sensitive analog circuits powered by a switching pre-regulator?: The LT1129CST-5#TRPBF achieves a PSRR of 64dB at 120Hz, but this degrades significantly at higher frequencies—typical PSRR drops to around 40–50dB at 1kHz and further decreases beyond 10kHz. When driven by a switching regulator (e.g., buck converter operating at 2MHz), high-frequency ripple from the pre-stage will not be adequately attenuated. For example, a 100mVpp ripple at 200kHz may appear as 1–10mV after regulation depending on actual PSRR, which could couple into sensitive analog sections. To mitigate this, additional post-filtering using LC networks or ferrite beads is often necessary before feeding the LT1129 input in precision measurement or RF applications.

What are the implications of mounting the LT1129CST-5#TRPBF on a standard FR4 PCB without thermal vias, and how much does trace width influence thermal resistance in continuous operation?: Mounting the LT1129CST-5#TRPBF without thermal vias or adequate copper pours increases the effective thermal resistance between the die and ambient air, potentially raising junction temperatures beyond safe limits. The SOT-223 package has a junction-to-ambient thermal resistance of about 65–80°C/W in open-air conditions. With a 6V input delivering 700mA, power dissipation is 0.7W, leading to a temperature rise of 45–56°C above ambient. On a 2-layer FR4 board with limited copper, this could push the junction past 100°C even at 40°C ambient, risking thermal shutdown or reduced lifespan. Adding a 2x2 array of 1mm thermal vias connected to a 1oz inner plane can reduce thermal resistance by 20–30%, improving reliability in compact designs.

Can the LT1129CST-5#TRPBF be substituted with the MIC2954-02WS-TR in industrial control systems requiring wide input voltage tolerance and extended temperature range?: The MIC2954-02WS-TR is a direct substitute offering similar 5V output and 1A current capability, but it lacks integrated reverse polarity protection present in the LT1129CST-5#TRPBF. Additionally, the MIC2954 typically requires careful attention to layout due to higher quiescent current and sensitivity to input transients. While both operate over 0°C to 125°C and accept inputs up to 26V, the LT1129’s superior protection features make it preferable in industrial settings where wiring errors or ESD events are likely. Substitution is possible only if external protection diodes and input filtering are added to match the robustness profile of the LT1129.

Does the LT1129CST-5#TRPBF support enable functionality, and how can this feature improve system-level power management in multi-rail embedded designs?: Yes, the LT1129CST-5#TRPBF includes an enable pin that allows logic-level control over output state. By connecting this pin to a microcontroller GPIO, the regulator can be turned off during sleep modes, reducing total system power consumption. In a multi-rail design with multiple regulators, sequencing can be implemented so that only necessary rails are active during idle periods. For example, disabling the LT1129CST-5#TRPBF when the MCU enters deep sleep cuts quiescent losses from 70µA to zero, extending battery life by several hours in portable devices. This also prevents inrush current when power is reapplied, aiding compliance with surge immunity standards.

What is the significance of the Moisture Sensitivity Level (MSL) rating of 1 for the LT1129CST-5#TRPBF, and does this affect storage or reflow soldering procedures in mass production?: An MSL rating of 1 indicates the LT1129CST-5#TRPBF is not susceptible to moisture-induced damage and can be stored indefinitely at room conditions without baking. This simplifies inventory management and reduces manufacturing costs in high-volume production. Standard lead-free reflow profiles (e.g., peak 245°C for <10 seconds) are fully compatible. There is no need for nitrogen reflow or special handling, unlike components rated MSL 3 or higher. This reliability in packaging enhances yield consistency across assembly lines using automated pick-and-place systems.

How does the LT1129CST-5#TRPBF behave under transient load steps typical in motor-driven applications, and what capacitance requirements are needed for stability?: The LT1129CST-5#TRPBF is internally compensated for stability with ceramic output capacitors, but adequate bulk capacitance is essential during fast load transients. A minimum of 10µF tantalum or 22µF X7R ceramic capacitor is recommended near the output to suppress droop and prevent undershoot. In motor applications where current can change rapidly (e.g., 0A to 700mA in 10µs), insufficient capacitance causes output voltage to dip below 4.7V, potentially resetting microcontrollers. Adding a small ESR (e.g., 1–10Ω) in series with the capacitor improves phase margin and damping, ensuring loop stability without oscillations. Overshoot during turn-on should also be controlled via soft-start behavior inherent in the design.

Are there any layout considerations specific to the SOT-223-3 package of the LT1129CST-5#TRPBF that impact EMI performance or thermal integrity in RF-susceptible environments?: Yes, the exposed pad on the bottom of the SOT-223-3 must be soldered directly to a large copper pour or ground plane to ensure both thermal and electrical connection. Poor pad attachment increases parasitic inductance and raises ground impedance, which can degrade PSRR and introduce noise into nearby analog traces. Additionally, long input/output traces increase susceptibility to radiated interference; these should be routed away from high-speed digital lines. A solid ground plane under the regulator minimizes loop area and reduces conducted emissions. Keeping bypass capacitors within 5mm of the input pins further enhances high-frequency rejection, critical in mixed-signal systems.

What environmental certifications apply to the LT1129CST-5#TRPBF, and how do RoHS3 and REACH status influence global regulatory compliance for consumer electronics?: The LT1129CST-5#TRPBF is RoHS3 compliant, meaning it meets all restrictions including stricter limits on substances like DEHP and TBP. It is also REACH unaffected, indicating no SVHCs (Substances of Very High Concern) are intentionally added above threshold levels. These statuses ensure the component can be used in products destined for markets such as the EU, Japan, and California without additional documentation or substitution risks. For OEMs designing white-label devices, this simplifies CE marking and export clearance processes, avoiding potential recalls due to non-compliant materials.

How does the LT1129CST-5#TRPBF compare to modern switching regulators like the TPS62840 in terms of efficiency when converting 12V to 5V at 500mA in a compact form factor?: At 500mA output from a 12V input, the LT1129CST-5#TRPBF dissipates 3.5W (7V × 500mA), resulting in ~58% efficiency assuming linear regulation. In contrast, the TPS62840 switching regulator achieves over 90% efficiency under the same conditions, drastically reducing heat generation and power loss. However, the LT1129 offers advantages in noise-critical analog circuits due to its inherently low output ripple (<10mVpp) and excellent PSRR at low frequencies, whereas switchers introduce switching noise that requires filtering. Thus, the choice depends on trade-offs: efficiency vs. simplicity, heat vs. noise—not absolute superiority.

Parts with Similar Specifications

The three parts on the right have similar specifications to Analog Devices Inc. LT1129CST-5#TRPBF

Product Attribute
Part Number	LT1129CST-3.3#TRPBF	LT1129CS8-5#TRPBF	LT1129CST-5#PBF	LT1129CT-5#PBF
Manufacturer	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.
Output Configuration	-	-	-	-
Package / Case	-	196-LFBGA	16-DIP (0.300', 7.62mm)	64-VFQFN Exposed Pad
Protection Features	-	-	-	-
Output Type	-	Current - Unbuffered	Voltage - Buffered	-
Control Features	-	-	-	-
Voltage - Output (Min/Fixed)	-	-	-	-
Operating Temperature	-	-40°C ~ 85°C	0°C ~ 70°C	-40°C ~ 85°C
Voltage Dropout (Max)	-	-	-	-
Voltage - Input (Max)	-	-	-	-
Voltage - Output (Max)	-	-	-	-
Supplier Device Package	-	196-NFBGA (12x12)	16-PDIP	64-VQFN (9x9)
Package	-	Tape & Reel (TR)	Tube	Tape & Reel (TR)
Current - Quiescent (Iq)	-	-	-	-
PSRR	-	-	-	-
Mounting Type	-	Surface Mount	Through Hole	Surface Mount
Base Product Number	-	DAC34H84	MAX500	ADS62P42
Series	-	-	-	-
Current - Supply (Max)	-	-	-	-
Number of Regulators	-	-	-	-
Current - Output	-	-	-	-

LT1129CST-5#TRPBF Datasheet PDF

Download LT1129CST-5#TRPBF pdf datasheets and Analog Devices Inc. documentation for LT1129CST-5#TRPBF - Analog Devices Inc..

Environmental Information: Material Declaration LT1129CST-5#TRPBF.pdf
HTML Datasheet: LT1129(-3.3,-5) Datasheet.pdf
PCN Assembly/Origin: 2.73KHz.pdf
Other Related Documents: Tape and Reel Packaging.pdf

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Customer Reviews

Evaluation: 10 Articles

Dani***alkerTech

Jun 1, 2026

Product works, but setup took more effort than expected. Once configured the MCU ran reliably, although documentation support felt older compared with newer platforms. Fine for maintenance projects.
Yuki***aka88

May 26, 2026

信号通信プロジェクトでこのRS-485トランシーバーを使用しました。設置は簡単で、長距離ケーブルでも通信は安定していました。消費電力も、以前使用していたものより低くなっています。
Stev***aker

May 20, 2026

Solid diode for power rectification. Works well in switching circuits.
Bran***Lewis

May 11, 2026

Compact FPGA with good performance. Suitable for basic signal processing tasks.
Oliv***arris

May 7, 2026

Reliable I/O expander. Works well in embedded control applications.
Jess***Jones

Apr 17, 2026

It offers good value for the price, and the specifications match the description. I’ve been using it for two days with no issues, and I’ll definitely buy it again if I need it in the future.
Mich***Smith

Apr 17, 2026

Shipping was on time, the component pins are neatly aligned, and I tested 10 of them with a multimeter—all readings were within the specified range. Highly recommended.
Aman***arris

Apr 3, 2026

It was great—the entire process, from placing the order to receiving the package, went very smoothly. The components were consistent, the price was fair, and I had a very pleasant shopping experience.
Mike***nch

Apr 3, 2026

Better than expected! The resistance and capacitance readings were spot-on, and it passed the test on the first try. The service was reliable, and the packaging was thoughtful—I highly recommend it.
Daic***K.

Mar 23, 2026

Very good. No issue after long time testing.

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