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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

STMicroelectronics LDS3985M30R

Name: LDS3985M30R
Brand: STMicroelectronics
SKU: LDS3985M30R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LDS3985M30R

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: SC-74A, SOT-753

Datasheet:: LDS3985M30R.pdf

Description:: IC REG LINEAR 3V 300MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Product details

Overview

LDS3985M30R from STMicroelectronics is a BiCMOS low-dropout linear voltage regulator delivering 3.0 V at up to 300 mA output current, with 150 mV typical dropout at full load and 30 µV_RMS output noise (10 Hz–100 kHz). It operates from 2.5 V to 6 V input, features logic-controlled shutdown (VINH), and is stable with low-ESR ceramic capacitors. Designed for battery-powered wireless systems including mobile phones and portable information appliances.

For engineers reviewing the LDS3985M30R datasheet, LDS3985M30R pinout, LDS3985M30R application, or LDS3985M30R equivalent, key selection criteria include ultra-low quiescent current (85 µA typ. no-load), fast 240 µs turn-on time, automotive-grade thermal range options, and precise 3.0 V fixed output with ±2% tolerance over –40 °C to 125 °C.

Technical Context

The LDS3985M30R implements a BiCMOS architecture enabling simultaneous ultra-low dropout (150 mV @ 300 mA), sub-100 µA quiescent current, and high PSRR (55 dB @ 1 kHz). Its internal current and thermal limiting protect against fault conditions without external components.

Logic-controlled inhibit (VINH) enables system-level power management: device enters <1.5 µA OFF mode when VINH ≤ 0.4 V, and resumes regulation when VINH ≥ 1.2 V. The bypass (BYP) pin accepts a 33 nF capacitor to suppress high-frequency noise and improve transient response.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.0 V ±2% (over –40 °C to 125 °C), enabling direct replacement of 3.0 V logic rails without feedback resistors.
Dropout Voltage	150 mV typical at 300 mA load - supports operation down to 3.15 V input while maintaining regulation.
Quiescent Current	85 µA typical at no load; rises to 200 µA at 300 mA - minimizes battery drain in always-on subsystems.
Output Noise	30 µV_RMS (10 Hz–100 kHz) - suitable for noise-sensitive analog/RF circuitry without additional filtering.
Supply Rejection	55 dB at 1 kHz - attenuates switching regulator ripple upstream, reducing need for bulk input capacitance.
Turn-on Time	240 µs typical (with 33 nF BYP cap) - enables rapid wake-up from low-power states in portable devices.
Shutdown Current	Max 1.5 µA in OFF mode - ensures negligible leakage during deep sleep, critical for multi-day battery life.

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 2.95 mm × 1.60 mm footprint, 1.45 mm height, ECOPACK® compliant.

Pin/Terminal	Circuit Role	Design Meaning
1 (VI)	LDO input voltage	Accepts 2.5–6 V supply; withstands non-repetitive 6.5 V spikes (200 ms).
2 (GND)	Common ground	Reference node for all internal circuitry; must be low-impedance connection to system ground plane.
3 (VINH)	Inhibit control input	Active-high enable: ≥1.2 V = ON; ≤0.4 V = OFF; requires external pull-down if unused.
4 (BYP)	Bypass capacitor terminal	Connects to 33 nF capacitor to reduce internal reference noise and improve AC performance.
5 (VO)	Regulated output	Delivers stable 3.0 V; requires 2.2 µF output capacitor (5–5000 mΩ ESR) for stability.

Key Features

Feature	Design Value
Ultra-low dropout	150 mV @ 300 mA enables use with single-cell Li-ion (3.0–4.2 V) or 3.3 V supply rails near end-of-discharge.
Low-noise regulation	30 µV_RMS noise and 55 dB PSRR allow direct powering of RF transceivers, ADCs, and precision sensors.
Logic-controlled shutdown	VINH input draws only ±1 nA, permitting direct interface with GPIOs without level-shifting or current-limiting resistors.
Thermal & current protection	Internal foldback current limit and 160 °C thermal shutdown prevent damage during sustained overload or PCB overheating.
Wide temperature range	Specified from –40 °C to +125 °C junction temperature - qualified for under-hood and industrial ambient environments.

Applications

Mobile Phone Power Management

Wearable Sensor Node

Use Scenario: Local 3.0 V supply for baseband processor I/O and PMIC sequencing logic in compact smartphone designs.

IC Role / Device Role / Timing Role: Primary LDO regulator providing clean, low-noise 3.0 V rail with fast enable/disable for dynamic power gating.

Use Value: 240 µs turn-on time synchronizes with SoC wake-up signals; 85 µA quiescent current extends standby battery life.

Use Scenario: Power source for MEMS accelerometers, environmental sensors, and BLE radio in coin-cell–powered wearables.

IC Role / Device Role / Timing Role: Low-quiescent LDO converting 3.6 V LiPo to regulated 3.0 V, enabled only during sensor readout cycles.

Use Value: <1.5 µA shutdown current preserves coin-cell capacity over multi-week deployment; 30 µV_RMS noise avoids sensor measurement corruption.

Industrial IoT Edge Controller

Automotive Body Control Module

Use Scenario: Secondary 3.0 V rail for isolated CAN transceiver bias and microcontroller peripherals in DIN-rail mounted gateways.

IC Role / Device Role / Timing Role: Fault-tolerant local regulator with thermal/current limiting, supporting wide-input industrial 5–24 V supplies.

Use Value: 125 °C max operating temperature and internal protection eliminate need for external thermal monitoring or current sense circuits.

Use Scenario: 3.0 V supply for LIN transceiver and microcontroller I/O in door module electronics exposed to under-dash temperatures.

IC Role / Device Role / Timing Role: AEC-Q100 qualified LDO (DFN6 variant) delivering stable 3.0 V across –40 °C to +85 °C ambient.

Use Value: 55 °C/W junction-to-ambient thermal resistance (DFN6) enables operation without heatsinking in confined enclosures.

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Torex XC6206P302MR	300 mA rated, but 350 mV dropout @ 300 mA; 45 µV_RMS noise; no inhibit pin.	Lacks logic-controlled shutdown - requires external MOSFET for system-level power gating.	Select when cost sensitivity outweighs need for integrated enable and lowest noise.
ON Semiconductor NCP114AMX30T2G	300 mA rated, 200 mV dropout @ 300 mA; 120 µA quiescent current; 40 µV_RMS noise.	Higher quiescent current reduces battery runtime in always-on sensing nodes.	Select when wider input range (1.7–5.5 V) is required, and 120 µA IQ is acceptable.

Compared with XC6206P302MR and NCP114AMX30T2G, LDS3985M30R delivers superior dropout (150 mV), lower noise (30 µV_RMS), and integrated shutdown - making it optimal for space-constrained, battery-critical applications demanding fast response and minimal leakage.

Availability

LDS3985M30R is available at Aetrix Electronics and suitable for mobile phone power management, wearable sensor nodes, and industrial IoT edge controllers requiring stable component supply with guaranteed long-term availability.

Supply support for LDS3985M30R includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The LDS3985 series belongs to ST's high-performance LDO portfolio, engineered specifically for ultra-low-power, low-noise, and fast-transient applications in battery-operated and automotive electronics.

FAQ

What is the minimum input voltage required for regulation at 300 mA load?

The LDS3985M30R requires a minimum input voltage of 3.15 V to maintain 3.0 V output at 300 mA load, based on its 150 mV typical dropout specification. Input voltages below 2.5 V are not supported per absolute maximum ratings, and regulation is not guaranteed below VI = VO + VDROP.

Can the BYP pin be left unconnected?

No - the BYP pin must be connected to a 33 nF capacitor (as specified in the datasheet) to stabilize the internal reference and achieve rated noise performance (30 µV_RMS) and PSRR (55 dB). Leaving it open degrades AC performance and may cause instability under transient loads.

Is the LDS3985M30R qualified for automotive applications?

The LDS3985M30R itself is the standard industrial-grade part in SOT23-5L. For automotive use, ST offers the pin-compatible LDS3985PU30R in DFN6 (3×3 mm) package, qualified to AEC-Q100 Grade 3 (–40 °C to +85 °C) with advanced screening per AEC-Q001/Q002.

What output capacitor ESR range ensures stability?

The LDS3985M30R is stable with output capacitors having ESR between 5 mΩ and 5000 mΩ, as verified with 2.2 µF ceramic capacitors. Unlike older LDOs, it does not require minimum ESR, enabling use of low-ESR X7R/X5R ceramics without external compensation.

LDS3985M30R Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SC-74A, SOT-753

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 6V

Voltage - Output (Min/Fixed):: 3V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.25V @ 300mA

Current - Output:: 300mA

Current - Quiescent (Iq):: 150 µA

Current - Supply (Max):: 300 µA

PSRR:: 55dB ~ 50dB (1kHz ~ 10kHz)

Control Features:: Shutdown

Protection Features:: Over Current, Over Temperature

Operating Temperature:: -40°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

LDS3985M30R FAQ

1.How can I place an order for LDS3985M30R through Aetrix?

Please submit a Request for Quotation (RFQ) for LDS3985M30R on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LDS3985M30R reliable?

The price and inventory of LDS3985M30R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LDS3985M30R is usually 5 days.

3.What payment methods are accepted for LDS3985M30R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LDS3985M30R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LDS3985M30R?

LDS3985M30R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LDS3985M30R order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LDS3985M30R?

For technical support, including LDS3985M30R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LDS3985M30R requirements.

6.How does Aetrix verify that LDS3985M30R is sourced from the original manufacturer or authorized distributors?

All LDS3985M30R products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LDS3985M30R meets industry standards.

7.What is the process for return or replacement of LDS3985M30R?

All LDS3985M30R units undergo pre-shipment inspection (PSI). If there is an issue with LDS3985M30R, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LDS3985M30R part is unused and in its original packaging.

Return procedure for LDS3985M30R:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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