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

onsemi NCP3985SN275T1G

Name: NCP3985SN275T1G
Brand: onsemi
SKU: NCP3985SN275T1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: NCP3985SN275T1G

Manufacturer:: onsemi

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

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

Datasheet:: NCP3985SN275T1G.pdf

Description:: IC REG LINEAR 2.75V 150MA 5TSOP

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Product details

Overview

NCP3985SN275T1G from onsemi is a micropower, 150 mA ultra-low dropout linear voltage regulator with fixed 2.75 V output, BiCMOS architecture, 105 mV typical dropout at 150 mA, 20 µV_RMS output noise (with 100 nF C_noise), and 70 dB PSRR at 1 kHz - designed for noise-sensitive analog power rails in portable battery-powered systems.

For engineers reviewing the NCP3985SN275T1G datasheet, pinout, applications, or equivalent options, this page delivers verified technical context, TSOP-5 package mapping, active discharge behavior, thermal shutdown thresholds, and validated alternatives for low-noise LDO selection in audio/video, GPS, and PDA subsystems.

Technical Context

The NCP3985SN275T1G integrates a bandgap reference, error amplifier, PMOS pass device, and active discharge transistor in a BiCMOS process to simultaneously achieve low ground current (70–220 µA across load), high PSRR (70 dB @ 1 kHz), and ultra-low noise (20 µV_RMS). Its C_noise pin provides direct access to the internal reference node for external capacitor-based noise filtering.

It features logic-controlled enable (CE) with 0.4 V/1.2 V thresholds, thermal shutdown at 150 °C ±20 °C hysteresis, and current limiting set to 200 mA minimum (310 mA typical). Stability is guaranteed with ≥1 µF ceramic output capacitors and no ESR lower limit requirement.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 2.75 V ±3% over 1–150 mA load and −40 °C to +85 °C - ensures stable biasing for 2.75 V–tolerant analog ICs without external feedback.
Dropout Voltage	105 mV typical at 150 mA - enables operation with Vin as low as 2.855 V while maintaining regulation, critical for single-cell Li-ion or Li-poly systems.
Output Noise	20 µV_RMS (10 Hz–100 kHz, 100 nF C_noise) - suppresses audible noise in audio codecs and phase jitter in RF synthesizers.
PSRR	70 dB at 1 kHz, 55 dB at 10 kHz - rejects switching noise from adjacent DC-DC converters feeding mixed-signal SoCs.
Ground Current	70 µA at 1 mA load, 220 µA at 150 mA - minimizes quiescent power loss in always-on sensor nodes and real-time clock domains.
Enable Threshold	CE low ≤0.4 V disables regulator; CE high ≥1.2 V enables - supports direct interfacing with 1.8 V/3.3 V GPIO without level-shifting.
Thermal Shutdown	Activates at 150 °C junction temperature with 20 °C hysteresis - prevents permanent damage during sustained overload or poor PCB thermal design.

Pinout & Package

TSOP-5 (Case 483), 3.00 mm × 1.50 mm × 0.95 mm body, 0.95 mm pitch, Pb-free, moisture sensitivity level 1.

Pin/Terminal	Circuit Role	Design Meaning
1 (Vin)	Input power supply	Accepts 2.5–5.5 V input; must be decoupled with ≥0.1 µF ceramic capacitor near pin to suppress high-frequency noise.
2 (GND)	Power ground reference	Low-impedance return path for regulator current and C_noise; requires solid copper pour under package for thermal dissipation.
3 (CE)	Chip enable control	Active-high logic input; internal 5 MΩ pull-down ensures safe default-off state when left floating or driven low.
4 (C_noise)	Noise reduction node	Direct connection to internal bandgap reference; 10–100 nF capacitor to GND reduces output noise by up to 5 µV_RMS.
5 (Vout)	Regulated output	Delivers 2.75 V ±3% to load; stable with ≥1 µF ceramic capacitor; active discharge circuit rapidly pulls Vout to GND when CE is low.

Key Features

Feature	Design Value
Ultra-low noise output	20 µV_RMS (10 Hz–100 kHz) with 100 nF C_noise capacitor - meets stringent SNR requirements for ADC reference supplies and RF LNA bias rails.
Active discharge circuit	Forces Vout to GND within milliseconds of CE deactivation - eliminates hold-up voltage that could cause latch-up in downstream logic or memory.
Micropower sleep mode	≤1 µA disable current - extends battery life in wake-on-event architectures such as GPS tracking or environmental sensors.
High PSRR across frequency	70 dB at 120 Hz and 1 kHz, 55 dB at 10 kHz - maintains clean supply under ripple from buck converters operating at 500 kHz–2 MHz switching frequencies.
Stable with low-ESR ceramics	No minimum ESR requirement for 1–10 µF output capacitors - enables use of compact, high-reliability X7R/X5R MLCCs without stability risk.

Applications

Audio Codec Power Rail	GPS Receiver LNA Bias
Use Scenario: Powers analog front-end of stereo audio codec in smartphone or portable media player. IC Role / Device Role / Timing Role: Low-noise 2.75 V supply for DAC/ADC reference and op-amp biasing. Use Value: 20 µV_RMS noise prevents audible hiss; 70 dB PSRR blocks ripple from system PMIC's 2 MHz buck converter.	Use Scenario: Supplies low-noise bias to GPS RF low-noise amplifier in handheld navigation device. IC Role / Device Role / Timing Role: Clean 2.75 V rail minimizing phase noise degradation in 1.575 GHz L1-band reception. Use Value: Ultra-low dropout (105 mV) allows operation from partially discharged 3.0 V Li-ion cell; active discharge prevents LNA latch-up during power cycling.
PDA Core Logic Supply	Portable Medical Sensor Analog Front-End
Use Scenario: Provides regulated 2.75 V to microcontroller core and SRAM in palm-sized PDA. IC Role / Device Role / Timing Role: Primary low-dropout regulator for digital logic domain requiring fast transient response. Use Value: 150 mA capability supports burst-mode CPU operation; 220 µA max ground current at full load preserves battery runtime.	Use Scenario: Powers signal conditioning circuitry (instrumentation amp, filter, ADC driver) in wearable ECG monitor. IC Role / Device Role / Timing Role: Precision analog supply with tight voltage tolerance and minimal thermal drift. Use Value: ±3% output accuracy over −40 °C to +85 °C ensures consistent gain calibration; thermal shutdown protects against skin-contact overheating.

Audio Codec Power Rail

GPS Receiver LNA Bias

Use Scenario: Powers analog front-end of stereo audio codec in smartphone or portable media player.

IC Role / Device Role / Timing Role: Low-noise 2.75 V supply for DAC/ADC reference and op-amp biasing.

Use Value: 20 µV_RMS noise prevents audible hiss; 70 dB PSRR blocks ripple from system PMIC's 2 MHz buck converter.

Use Scenario: Supplies low-noise bias to GPS RF low-noise amplifier in handheld navigation device.

IC Role / Device Role / Timing Role: Clean 2.75 V rail minimizing phase noise degradation in 1.575 GHz L1-band reception.

Use Value: Ultra-low dropout (105 mV) allows operation from partially discharged 3.0 V Li-ion cell; active discharge prevents LNA latch-up during power cycling.

PDA Core Logic Supply

Portable Medical Sensor Analog Front-End

Use Scenario: Provides regulated 2.75 V to microcontroller core and SRAM in palm-sized PDA.

IC Role / Device Role / Timing Role: Primary low-dropout regulator for digital logic domain requiring fast transient response.

Use Value: 150 mA capability supports burst-mode CPU operation; 220 µA max ground current at full load preserves battery runtime.

Use Scenario: Powers signal conditioning circuitry (instrumentation amp, filter, ADC driver) in wearable ECG monitor.

IC Role / Device Role / Timing Role: Precision analog supply with tight voltage tolerance and minimal thermal drift.

Use Value: ±3% output accuracy over −40 °C to +85 °C ensures consistent gain calibration; thermal shutdown protects against skin-contact overheating.

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise LDO applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LP3985IMF-2.75/NOPB	Same 2.75 V output, but CMOS-only process; higher ground current (120 µA typ @ 150 mA), no C_noise pin, 35 µV_RMS noise.	Lacks active discharge and noise-reduction pin - unsuitable where rapid Vout decay or sub-25 µV_RMS noise is required.	Choose LP3985IMF-2.75/NOPB only if cost is primary constraint and noise/PSRR specs are relaxed.
TPS7A20275PDBVR	2.75 V output, 250 mA rating, 12 µV_RMS noise, but requires 0.5 µF min Cout and has no C_noise pin; 160 mV dropout at 250 mA.	Higher current capacity and lower noise, but larger dropout limits use in <3.0 V input systems; no active discharge.	Select TPS7A20275PDBVR when >200 mA load or <15 µV_RMS noise is mandatory, and active discharge is unnecessary.

Compared with LP3985IMF-2.75/NOPB, the NCP3985SN275T1G delivers 15 µV_RMS lower noise and active discharge; versus TPS7A20275PDBVR, it offers 105 mV lower dropout and dedicated noise filtering, at the expense of 100 mA lower current rating.

Availability

NCP3985SN275T1G is available at Aetrix Electronics and suitable for cellular telephones, GPS receivers, portable medical sensors, and PDA power management requiring stable component supply, long-term lifecycle support, and Pb-free compliance.

Supply support for NCP3985SN275T1G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The NCP3985SN275T1G belongs to onsemi's NCP3985 family of micropower, low-noise LDOs engineered specifically for battery-powered portable electronics where ultra-low dropout, high PSRR, and sub-25 µV_RMS noise are essential.

FAQ

What is the maximum input voltage rating for the NCP3985SN275T1G?

The NCP3985SN275T1G has an absolute maximum input voltage (Vin) rating of 6 V. Operation above 5.5 V is not recommended per electrical characteristics - the device is specified for reliable performance from 2.5 V to 5.5 V input across its full temperature and load range. Exceeding 6 V risks permanent damage to the internal BiCMOS pass device.

Does the NCP3985SN275T1G require an external capacitor on the Cnoise pin?

Yes, the NCP3985SN275T1G requires a capacitor (10 nF to 100 nF) between the C_noise pin and GND to achieve its specified 20 µV_RMS output noise. Without this capacitor, noise rises to 25 µV_RMS. The capacitor directly filters the internal bandgap reference node, and its value determines final noise floor - 100 nF yields optimal suppression.

What is the purpose of the active discharge circuit in the NCP3985SN275T1G?

The active discharge circuit in the NCP3985SN275T1G rapidly pulls the Vout pin to GND when the CE pin is driven low, eliminating residual output voltage within milliseconds. This prevents unintended operation or latch-up in downstream logic, memory, or RF components during power-down sequences - a critical feature for systems with strict power sequencing requirements.

Can the NCP3985SN275T1G operate with a 1 µF ceramic output capacitor?

Yes, the NCP3985SN275T1G is explicitly characterized and guaranteed stable with a 1 µF ceramic output capacitor (e.g., Murata GRM219R71E105K), and no minimum ESR is required. This enables use of small, high-reliability X7R/X5R MLCCs without compromising loop stability - unlike many older LDOs that demand tantalum or high-ESR capacitors.

What is the thermal shutdown threshold and hysteresis for the NCP3985SN275T1G?

The NCP3985SN275T1G activates thermal shutdown at a junction temperature of 150 °C (typical), with 20 °C hysteresis - meaning the device remains off until the die cools to approximately 130 °C before re-enabling. This threshold is guaranteed by design and characterization, not production-tested, and serves as last-resort protection against catastrophic failure due to sustained overload or inadequate PCB heat sinking.

NCP3985SN275T1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

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):: 5.5V

Voltage - Output (Min/Fixed):: 2.75V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.155V @ 150mA

Current - Output:: 150mA

Current - Quiescent (Iq):: 90 µA

Current - Supply (Max):: 220 µA

PSRR:: 70dB ~ 55dB (120Hz ~ 10kHz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 5-TSOP

NCP3985SN275T1G FAQ

1.How can I place an order for NCP3985SN275T1G through Aetrix?

Please submit a Request for Quotation (RFQ) for NCP3985SN275T1G 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 NCP3985SN275T1G reliable?

The price and inventory of NCP3985SN275T1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NCP3985SN275T1G is usually 5 days.

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Once your NCP3985SN275T1G 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 NCP3985SN275T1G?

For technical support, including NCP3985SN275T1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NCP3985SN275T1G requirements.

6.How does Aetrix verify that NCP3985SN275T1G is sourced from the original manufacturer or authorized distributors?

All NCP3985SN275T1G 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 NCP3985SN275T1G meets industry standards.

7.What is the process for return or replacement of NCP3985SN275T1G?

All NCP3985SN275T1G units undergo pre-shipment inspection (PSI). If there is an issue with NCP3985SN275T1G, 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 NCP3985SN275T1G part is unused and in its original packaging.

Return procedure for NCP3985SN275T1G:

1.Submit a request within 90 days.

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

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