Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

STMicroelectronics LDS3985M25R

Name: LDS3985M25R
Brand: STMicroelectronics
SKU: LDS3985M25R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: LDS3985M25R

Manufacturer:: STMicroelectronics

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

Package:: SC-74A, SOT-753

Datasheet:: LDS3985M25R.pdf

Description:: IC REG LINEAR 2.5V 300MA SOT23-5

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,502

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

LDS3985M25R from STMicroelectronics is a BiCMOS low-dropout linear voltage regulator delivering 300 mA output at fixed 2.5 V with 150 mV typical dropout at full load, 30 µV_RMS output noise (10 Hz–100 kHz), and logic-controlled shutdown. It operates from 2.5 V to 6 V input and is stable with low-ESR ceramic capacitors-ideal for battery-powered mobile phones and portable information appliances requiring ultra-low quiescent current (85 µA typ. no-load) and high PSRR (55 dB @ 1 kHz).

For engineers reviewing the LDS3985M25R datasheet, LDS3985M25R pinout, LDS3985M25R application, or LDS3985M25R equivalent, this page delivers verified package mapping (SOT23-5L), validated thermal performance (−40 °C to 125 °C), confirmed shutdown behavior (VINH ≤ 0.4 V = OFF), and real-world noise/line regulation specs critical for low-power embedded power rail design.

Technical Context

The LDS3985M25R implements a BiCMOS pass transistor architecture enabling ultra-low dropout (0.4 mV typ. @ 1 mA) and sub-100 µA quiescent current. Its internal current and thermal limiting protect against overload and fault conditions without external circuitry.

It features dual capacitor support: a 2.2 µF output capacitor for stability and transient response, plus a dedicated 33 nF bypass capacitor on the Bypass pin to suppress high-frequency noise and improve PSRR-critical for powering RF sections or precision analog blocks.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 2.5 V ±2% over −40 °C to 125 °C - ensures stable core voltage for 2.5 V logic or analog subsystems.
Dropout Voltage	150 mV typ. @ 300 mA - enables operation down to 2.65 V input, extending battery runtime in single-cell Li-ion systems.
Quiescent Current	85 µA typ. @ no load - minimizes standby power loss in always-on sensor nodes or wake-on-event circuits.
Output Noise	30 µV_RMS (10 Hz–100 kHz) - supports noise-sensitive ADCs, PLLs, or RF receivers without additional filtering.
PSRR	55 dB @ 1 kHz - suppresses switching noise from upstream DC/DC converters feeding the LDO input.
Shutdown Current	1.5 µA max. @ −40 °C to 125 °C - enables true zero-power off-state for system-level energy budgeting.
Turn-on Time	240 µs typ. - fast enough for dynamic power sequencing in multi-rail processors or FPGAs.

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 2.95 mm × 1.60 mm footprint, 0.95 mm pitch, ECOPACK® compliant, thermal resistance R_thJA = 255 °C/W.

Pin	Circuit Role	Design Meaning
1	VI	Input voltage supply pin - accepts 2.5 V to 6 V; must be decoupled with ≥1 µF ceramic capacitor.
2	GND	Common ground reference - connects to PCB ground plane for low-noise return path.
3	VINH	Inhibit control input - logic-high (≥1.4 V) enables output; logic-low (≤0.4 V) disables output and reduces IQ to <1.5 µA.
4	BYPASS	Noise reduction node - requires 33 nF capacitor to ground to lower high-frequency output impedance and boost PSRR.
5	VO	Regulated 2.5 V output - supplies load up to 300 mA; requires 2.2 µF low-ESR ceramic output capacitor.

Key Features

Feature	Design Value
Ultra-low dropout	150 mV @ 300 mA enables use with weak or aging batteries in portable devices.
Low-noise regulation	30 µV_RMS noise supports clean power for RF transceivers and high-resolution ADCs.
Logic-controlled shutdown	VINH pin allows microcontroller-driven power gating of peripheral rails to reduce system standby current.
Stable with ceramic caps	Eliminates need for costly tantalum or aluminum electrolytic capacitors - lowers BOM cost and improves reliability.
Wide temperature range	−40 °C to 125 °C operation qualifies for under-hood automotive modules and industrial edge sensors.

Applications

Mobile Handsets

Wearable Health Monitors

Use Scenario: Powering baseband processor I/O banks and camera sensor interfaces in compact smartphones.

IC Role / Device Role / Timing Role: Local 2.5 V LDO supplying noise-sensitive analog front-ends and digital I/O domains.

Use Value: 55 dB PSRR rejects noise from PMIC switching regulators; 240 µs turn-on supports fast modem wake-up sequences.

Use Scenario: Regulating power for ECG/PPG analog signal chains and Bluetooth LE radio in wrist-worn devices.

IC Role / Device Role / Timing Role: Primary low-noise 2.5 V supply for precision biopotential amplifiers and RF transceivers.

Use Value: 30 µV_RMS noise prevents baseline drift in µV-level bio-signals; 85 µA quiescent current extends 7-day battery life.

Industrial IoT Sensors

Automotive Body Control Modules

Use Scenario: Providing stable 2.5 V bias to MEMS accelerometers and LoRaWAN transceivers in remote environmental nodes.

IC Role / Device Role / Timing Role: Low-power, wide-temperature LDO enabling long-life battery operation in uncontrolled ambient conditions.

Use Value: −40 °C to 125 °C rating ensures functionality in outdoor enclosures; 1.5 µA shutdown current preserves battery during multi-year sleep cycles.

Use Scenario: Supplying 2.5 V to LIN transceiver bias rails and EEPROM interfaces in door module ECUs.

IC Role / Device Role / Timing Role: Automotive-grade local regulator meeting AEC-Q100 requirements for body electronics.

Use Value: DFN6 variant available with AEC-Q100 qualification; thermal shutdown (160 °C) protects against engine-bay thermal runaway.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Torex XC6206P252MR	2.5 V fixed, 150 mA max, 250 mV dropout @ 150 mA, no shutdown pin, SOT23-3 package	Limited current and no enable control - unsuitable for 300 mA loads or power-gated subsystems	Select only if cost sensitivity outweighs current capability and controllability needs
ON Semiconductor NCP114AMX25TBG	2.5 V fixed, 300 mA, 220 mV dropout @ 300 mA, 1.2 µA shutdown current, SOT23-5	Higher dropout and slightly higher noise (45 µV_RMS) - reduces battery headroom and analog SNR margin	Prefer when legacy ON Semi sourcing is required; verify thermal derating at 125 °C ambient

Compared with XC6206P252MR and NCP114AMX25TBG, the LDS3985M25R uniquely combines 300 mA capability, 150 mV dropout, 30 µV_RMS noise, and logic-enable in SOT23-5 - making it optimal for space-constrained, battery-critical designs demanding both performance and control.

Availability

LDS3985M25R is available at Aetrix Electronics and suitable for mobile handset power management, wearable health monitoring, and industrial IoT sensor nodes requiring stable component supply across extended temperature ranges and low-noise operation.

Supply support for LDS3985M25R 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 components for industrial, automotive, and consumer markets.

The LDS3985 belongs to ST's high-performance LDO family targeting ultra-low-noise, low-quiescent-current regulation in battery-powered and thermally constrained applications - emphasizing efficiency, stability, and functional safety readiness.

FAQ

What is the minimum input voltage required for stable 2.5 V output?

The LDS3985M25R requires a minimum input voltage of 2.5 V + V_DROP. At 300 mA load, typical dropout is 150 mV, so stable operation begins at 2.65 V. Below 2.5 V input, regulation is not guaranteed per datasheet Section 3 Absolute Maximum Ratings and Electrical Characteristics Table 5.

Can the BYPASS pin be left unconnected?

No. The BYPASS pin must be connected to a 33 nF capacitor to ground. Leaving it floating degrades PSRR by up to 20 dB and increases output noise - as confirmed in Figure 14 (PSRR vs frequency) and Table 5 note on eN measurement condition. A missing BYPASS cap violates the test setup used to guarantee 30 µV_RMS noise.

Is the LDS3985M25R qualified for automotive applications?

The LDS3985M25R itself is rated for −40 °C to 125 °C and meets industrial reliability standards, but it is not AEC-Q100 qualified. For automotive use, ST offers the pin-compatible LDS3985PU25R in DFN6 package, which is explicitly qualified per AEC-Q100 Grade 3 (−40 °C to 85 °C) and advanced screening per AEC-Q001/Q002.

What output capacitor ESR range ensures stability?

The LDS3985M25R is stable with ceramic capacitors having ESR between 5 mΩ and 5000 mΩ, as specified in Table 5 notes and Table 6. Unlike older LDOs, it does not require minimum ESR - enabling use of low-ESR X7R/X5R ceramics without series resistance, reducing board area and cost while improving transient response.

LDS3985M25R 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):: 2.5V

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

LDS3985M25R FAQ

1.How can I place an order for LDS3985M25R through Aetrix?

Please submit a Request for Quotation (RFQ) for LDS3985M25R 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 LDS3985M25R reliable?

The price and inventory of LDS3985M25R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LDS3985M25R is usually 5 days.

3.What payment methods are accepted for LDS3985M25R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LDS3985M25R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LDS3985M25R?

LDS3985M25R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LDS3985M25R 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 LDS3985M25R?

For technical support, including LDS3985M25R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LDS3985M25R requirements.

6.How does Aetrix verify that LDS3985M25R is sourced from the original manufacturer or authorized distributors?

All LDS3985M25R 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 LDS3985M25R meets industry standards.

7.What is the process for return or replacement of LDS3985M25R?

All LDS3985M25R units undergo pre-shipment inspection (PSI). If there is an issue with LDS3985M25R, 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 LDS3985M25R part is unused and in its original packaging.

Return procedure for LDS3985M25R:

1.Submit a request within 90 days.

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

Tech Hub

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…

2026-08-11 LDO Regulator: Dropout Voltage, Noise, PSRR and Power Dissipation

LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…

2026-08-06 Conditional Access Module: CAM, CI/CI+ and DVB Security

Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…

2026-08-03 Electronic Component Obsolescence: EOL Risks, Replacement Options and Last-Time Buy Strategy

Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.

2026-07-29 18650 Battery: Voltage, Capacity, Charging and Pack Design

18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…