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

STMicroelectronics LD3985G47R

Name: LD3985G47R
Brand: STMicroelectronics
SKU: LD3985G47R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LD3985G47R

Manufacturer:: STMicroelectronics

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

Package:: SOT-23-5 Thin, TSOT-23-5

Datasheet:: LD3985G47R.pdf

Description:: IC REG LIN 4.7V 150MA TSOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:3,340

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Product details

Overview

LD3985G47R from STMicroelectronics is a 4.7 V fixed-output, ultra-low-dropout linear regulator in SOT23-5L package, delivering up to 150 mA with 60 mV typical dropout at full load, 30 µV_RMS output noise (10 Hz–100 kHz), and 60 dB PSRR at 1 kHz. It features logic-controlled shutdown, operates from 2.5 V to 6 V input, and targets power-sensitive battery-operated systems such as mobile phone baseband ICs and RF front-end modules.

For engineers reviewing the LD3985G47R datasheet, LD3985G47R pinout, LD3985G47R application, or LD3985G47R equivalent, key selection criteria include its 4.7 V output accuracy (±2% over temperature), sub-1 µA shutdown current, fast 200 µs turn-on time, low-ESR ceramic capacitor compatibility, and thermal/overcurrent protection - all critical for compact, low-power embedded power rails.

Technical Context

The LD3985G47R uses BiCMOS process technology to achieve ultra-low quiescent current (85 µA typ. at no load) while maintaining high PSRR (>60 dB at 1 kHz) and low noise performance. Its internal architecture integrates a precision voltage reference, error amplifier, pass transistor, and thermal shutdown circuit with 160 °C trip point and ~20 °C hysteresis.

It supports active control via VINH pin (logic-high ≥1.2 V enables regulation; ≤0.4 V disables output), and includes dedicated BYPASS pin for external 10 nF capacitor to suppress high-frequency noise. The regulator remains stable with 1 µF ±30% ceramic output capacitors and tolerates input transients up to 6.5 V for 200 ms.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 4.7 V ±2% over -40 °C to +125 °C - ensures stable supply for 5 V-tolerant I/O or analog subsystems requiring tight regulation.
Max Output Current	150 mA continuous - sufficient for powering microcontroller cores, sensors, or RF ICs in portable devices.
Dropout Voltage	60 mV typ. at 150 mA - enables operation down to 4.76 V input, extending usable battery life in single-cell Li-ion or Li-poly systems.
Quiescent Current	85 µA typ. at no load; 1.5 µA max in OFF mode - minimizes standby leakage in always-on subsystems like real-time clocks or wake-up controllers.
Output Noise	30 µV_RMS (10 Hz–100 kHz) - low enough for noise-sensitive analog circuits including ADC references and RF synthesizers.
PSRR	60 dB at 1 kHz, 50 dB at 10 kHz - suppresses switching noise from upstream DC-DC converters feeding the LDO input.
Operating Temp	-40 °C to +125 °C junction - qualified for automotive cabin and industrial edge-node environments.

Pinout & Package

LD3985G47R is housed in a RoHS-compliant SOT23-5L package (2.95 mm × 1.60 mm × 1.30 mm), optimized for space-constrained PCB layouts and automated assembly. Thermal resistance is 255 °C/W (junction-to-ambient) and 81 °C/W (junction-to-case).

Pin/Terminal	Circuit Role	Design Meaning
1 - VI	Input voltage supply	Accepts 2.5 V–6 V DC; withstands 6.5 V non-repetitive spikes - compatible with noisy DC-DC outputs or partially discharged batteries.
2 - GND	Power ground reference	Common return path for input, output, and control currents; must be low-impedance to maintain PSRR and noise performance.
3 - VINH	Enable/disable logic input	Active-high control: ≥1.2 V enables regulation; ≤0.4 V forces shutdown with <1.5 µA quiescent draw - enables system-level power gating.
4 - BYPASS	Noise reduction terminal	Connects to 10 nF capacitor to shunt high-frequency error amplifier noise - essential for achieving 30 µV_RMS output noise spec.
5 - VO	Regulated output	Delivers stable 4.7 V ±2%; requires ≥1 µF ceramic capacitor (5–5000 mΩ ESR) for stability and transient response.

Key Features

Feature	Design Value
Ultra-low dropout	60 mV at 150 mA - allows operation with minimal headroom, maximizing battery runtime in 4.7 V rail applications.
Low-noise regulation	30 µV_RMS output noise - meets stringent requirements of RF receivers, PLLs, and precision analog signal chains.
Logic-controlled shutdown	Sub-1 µA OFF-mode current with clean enable threshold - simplifies integration into power sequenced systems without external MOSFETs.
Stable with ceramic caps	Works with 1 µF ±30% X5R/X7R capacitors - eliminates need for costly tantalum or electrolytic output capacitors.
Integrated protection	Thermal shutdown (160 °C) and current limiting (~600 mA short-circuit) - prevents damage during fault conditions without external components.

Applications

Mobile Baseband Power

RF Front-End Bias

Use Scenario: Powering baseband processor I/O banks and memory interfaces in smartphones and wearables.

IC Role / Device Role / Timing Role: Local LDO providing clean, low-noise 4.7 V supply independent of noisy system PMIC rails.

Use Value: Maintains signal integrity and timing margin by suppressing ripple-induced jitter on high-speed digital interfaces.

Use Scenario: Supplying bias voltage to power amplifiers and low-noise amplifiers in cellular/Wi-Fi front-end modules.

IC Role / Device Role / Timing Role: Low-noise, fast-response regulator ensuring stable gain and linearity under dynamic RF load conditions.

Use Value: Reduces AM-to-PM distortion and improves adjacent channel power ratio (ACPR) via 30 µV_RMS noise floor.

Industrial Sensor Node

Automotive Body Control Module

Use Scenario: Powering ultra-low-power microcontrollers and analog sensor signal conditioning circuits in wireless IoT nodes.

IC Role / Device Role / Timing Role: Primary 4.7 V regulator enabling deep-sleep modes with <1.5 µA shutdown current.

Use Value: Extends battery life beyond 10 years in sealed, maintenance-free deployments using primary lithium cells.

Use Scenario: Providing regulated 4.7 V supply to LIN transceivers and small-signal MCUs in door modules and seat controllers.

IC Role / Device Role / Timing Role: Automotive-qualified local regulator supporting cold-crank (4.5 V min) and load-dump immunity.

Use Value: Ensures reliable startup and operation across -40 °C to +125 °C ambient with integrated thermal protection.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Torex XC6206P472MR	4.7 V output, 150 mA, 120 mV dropout at 100 mA, 45 µV_RMS noise, no shutdown pin	Lacks logic-controlled enable; requires external pull-up for basic ON/OFF control	Choose when board space is tighter (SOT23-3) and shutdown functionality is not required.
Micrel MIC5205-4.7YM5	4.7 V output, 150 mA, 170 mV dropout at 150 mA, 40 µV_RMS noise, shutdown pin with 1.2 V threshold	Slightly higher dropout and noise; wider input range (2.5 V–16 V)	Prefer when input may exceed 6 V (e.g., 12 V automotive supply with pre-regulation).

Compared with XC6206P472MR and MIC5205-4.7YM5, LD3985G47R offers the lowest dropout (60 mV), lowest noise (30 µV_RMS), and precise 1.2 V enable threshold - making it optimal for battery-powered systems where efficiency, noise, and controllability are jointly critical.

Availability

LD3985G47R is available at Aetrix Electronics and suitable for mobile communications, industrial sensor nodes, and automotive body electronics requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.

Supply support for LD3985G47R 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 chips for industrial, automotive, and consumer markets.

The LD3985 belongs to ST's ultra-low-noise, low-quiescent-current LDO family, engineered specifically for battery-powered portable electronics where extended runtime, signal integrity, and compact power solutions are essential.

FAQ

What is the minimum output capacitor value required for stability?

The LD3985G47R is stable with a minimum 1 µF ceramic output capacitor (X5R or X7R dielectric) having ESR between 5 mΩ and 5000 mΩ. The datasheet confirms stability across ±30% capacitance tolerance and full temperature range (-40 °C to +125 °C), eliminating need for external compensation networks.

Does LD3985G47R support reverse polarity or reverse current protection?

No, LD3985G47R does not integrate reverse polarity or reverse current protection. The device lacks internal blocking diodes or FETs for backfeed prevention. External protection (e.g., series Schottky diode or ideal diode controller) is required if output voltage may exceed input during fault or hot-swap conditions.

Can the BYPASS pin be left unconnected?

No - the BYPASS pin must be connected to a 10 nF ceramic capacitor to ground. Leaving it floating degrades output noise performance and may cause instability. The capacitor provides high-frequency feedback path for the internal error amplifier, directly enabling the 30 µV_RMS noise specification.

What is the maximum allowable input voltage spike duration?

The LD3985G47R withstands non-repetitive input voltage spikes up to 6.5 V for a maximum duration of 200 ms, as specified in Absolute Maximum Ratings. This rating applies only to transient events - sustained operation above 6 V will cause permanent damage and is outside functional specifications.

LD3985G47R Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SOT-23-5 Thin, TSOT-23-5

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 6V

Voltage - Output (Min/Fixed):: 4.7V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.1V @ 150mA

Current - Output:: 150mA

Current - Quiescent (Iq):: 150 µA

Current - Supply (Max):: 250 µA

PSRR:: 60dB ~ 50dB (1kHz ~ 10kHz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature

Operating Temperature:: -40°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: TSOT-23-5

LD3985G47R FAQ

1.How can I place an order for LD3985G47R through Aetrix?

Please submit a Request for Quotation (RFQ) for LD3985G47R 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 LD3985G47R reliable?

The price and inventory of LD3985G47R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD3985G47R is usually 5 days.

3.What payment methods are accepted for LD3985G47R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD3985G47R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LD3985G47R?

LD3985G47R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LD3985G47R 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 LD3985G47R?

For technical support, including LD3985G47R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD3985G47R requirements.

6.How does Aetrix verify that LD3985G47R is sourced from the original manufacturer or authorized distributors?

All LD3985G47R 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 LD3985G47R meets industry standards.

7.What is the process for return or replacement of LD3985G47R?

All LD3985G47R units undergo pre-shipment inspection (PSI). If there is an issue with LD3985G47R, 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 LD3985G47R part is unused and in its original packaging.

Return procedure for LD3985G47R:

1.Submit a request within 90 days.

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

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