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STMicroelectronics LD2985AM50R
- Part No.:
- LD2985AM50R
- Manufacturer:
- STMicroelectronics
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LD2985AM50R.pdf
- Description:
- IC REG LINEAR 5V 150MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,170
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Product details
Overview
LD2985AM50R from STMicroelectronics is a 150 mA fixed-output low-dropout linear voltage regulator with 5.0 V output, 280 mV dropout at 150 mA load, 30 µVrms output noise, and TTL-compatible inhibit control on Pin 3. It operates from –40 °C to 125 °C and is optimized for battery-powered portable electronics requiring ultra-low quiescent current (≤1 µA in shutdown) and high PSRR.
For engineers reviewing the LD2985AM50R datasheet, LD2985AM50R pinout, LD2985AM50R application, or LD2985AM50R equivalent, this page delivers verified electrical specs, SOT23-5L terminal mapping, real-world use cases in power-sensitive embedded systems, and validated alternative regulators with documented functional trade-offs.
Technical Context
The LD2985AM50R employs a PNP pass transistor architecture enabling ultra-low dropout (7 mV at 1 mA, 280 mV at 150 mA) and sub-1 µA shutdown current. Its internal feedback network sets a precise 5.0 V output with ±2% tolerance over temperature and load.
It integrates thermal and current limiting, supports external bypass capacitor (10 nF to GND on Pin 4) for noise reduction to 30 µVrms, and accepts input voltages from 2.5 V to 16 V. The INHIBIT pin (Pin 3) is not internally pulled up and requires explicit logic-level drive (VIL ≤ 0.15 V, VIH ≥ 2 V) for reliable enable/disable control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 5.0 V ±2% (1.8 V to 5.0 V variants exist; this part is fixed 5.0 V) |
| Max Output Current | 150 mA continuous - sufficient for microcontroller cores, sensors, and RF front-ends |
| Dropout Voltage | 280 mV at 150 mA - enables operation with input as low as 5.28 V while maintaining regulation |
| Quiescent Current | 80 µA at no load; <1 µA in inhibit-off state - extends battery life in standby modes |
| Output Noise | 30 µVrms (300 Hz–50 kHz) with 10 nF bypass capacitor - suitable for noise-sensitive analog/RF circuits |
| PSRR | 45 dB at 1 kHz - suppresses ripple from noisy DC-DC converters upstream |
| Operating Temp | –40 °C to +125 °C junction - qualified for automotive cabin and industrial edge environments |
Pinout & Package
SOT23-5L package: 5-pin surface-mount, 1.6 mm × 2.9 mm footprint, 0.95 mm pitch, exposed pad optional per manufacturer layout guidance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Input supply connection | Accepts 2.5–16 V DC; requires ≥1 µF ceramic capacitor placed within 12.7 mm of pin |
| 2 (GND) | Power ground reference | Common return for input, output, bypass, and inhibit; must connect to clean analog ground plane |
| 3 (INHIBIT) | Logic-controlled enable/disable | TTL-compatible; <0.15 V disables regulator (IQ <1 µA); ≥2 V enables; must not float |
| 4 (BYPASS) | Noise reduction node | Connect 10 nF ceramic capacitor to GND to reduce output noise to 30 µVrms |
| 5 (OUT) | Regulated 5.0 V output | Delivers up to 150 mA; requires 1–3.3 µF ceramic output capacitor depending on VOUT |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low dropout | 7 mV at 1 mA load - enables single-cell Li-ion (3.0 V min) to power 5 V logic via boost+LDO architecture |
| Sub-microamp shutdown | <1 µA IQ when INHIBIT = LOW - eliminates battery drain during system sleep without external switches |
| Low-noise output | 30 µVrms with 10 nF BYPASS cap - meets ADC reference and RF LNA supply requirements without additional filtering |
| Integrated protection | Thermal shutdown and current limiting - prevents damage during overload or ambient overheating |
| Wide input range | 2.5 V to 16 V - supports direct connection to 12 V rails, USB PD outputs, or multi-cell battery packs |
Applications
| Portable Medical Sensors | Industrial IoT Edge Nodes |
|---|---|
|
Use Scenario: Wearable ECG patch with ultra-low-power MCU and analog front-end. IC Role / Device Role / Timing Role: Local 5.0 V supply for op-amps and SAR ADC reference, enabled only during measurement bursts. Use Value: 30 µVrms noise ensures <12-bit ENOB; <1 µA shutdown cuts idle power by >99% vs. standard LDOs. |
Use Scenario: Battery-powered vibration sensor node in predictive maintenance system. IC Role / Device Role / Timing Role: Primary 5.0 V rail for MEMS accelerometer and BLE SoC, controlled via MCU GPIO. Use Value: 280 mV dropout allows operation down to 5.28 V input, extending usable battery range by ~18% vs. 400 mV-dropout alternatives. |
| Automotive Cabin Infotainment | Smart Home Audio Devices |
|
Use Scenario: USB-C powered car dock with display and voice assistant module. IC Role / Device Role / Timing Role: Clean 5.0 V supply for audio codec and touch controller, isolated from noisy 12 V vehicle bus. Use Value: 45 dB PSRR at 1 kHz rejects alternator ripple; –40 °C to 125 °C rating covers under-dash thermal environment. |
Use Scenario: Voice-controlled smart speaker with always-on mic array and DSP. IC Role / Device Role / Timing Role: Low-noise 5.0 V source for MEMS microphone bias and ADC, activated only during wake-word detection. Use Value: Inhibit control synchronizes power with DSP activity, reducing average system IQ by 85% versus always-on regulation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-noise, inhibit-enabled LDO applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS7A2050PDBVR | Lower IQ (6.5 µA typ. active), but higher dropout (175 mV @ 150 mA); no dedicated BYPASS pin | Lacks integrated noise-reduction path; requires external RC filter for 30 µVrms performance | Prefer when board space is constrained and noise <50 µVrms is acceptable |
| MCP1703T-5002E/MB | Higher dropout (400 mV @ 150 mA); no inhibit function - requires external MOSFET for shutdown | Cannot achieve <1 µA shutdown without added components; less suitable for burst-mode sensing | Select only if cost is primary constraint and system lacks GPIO for enable control |
Compared with TPS7A2050PDBVR and MCP1703T-5002E/MB, LD2985AM50R uniquely combines sub-1 µA inhibit-off current, 30 µVrms noise via dedicated BYPASS pin, and 280 mV dropout - making it optimal for battery-critical, noise-sensitive, and GPIO-constrained designs.
Availability
LD2985AM50R is available at Aetrix Electronics and suitable for portable medical sensors, industrial IoT edge nodes, automotive cabin infotainment, and smart home audio devices requiring stable component supply across extended temperature ranges and low-noise power delivery.
Supply support for LD2985AM50R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.
The LD2985 series belongs to ST's precision low-dropout regulator product line, engineered specifically for ultra-low-noise, ultra-low-quiescent-current power management in portable and battery-operated systems.
FAQ
What is the minimum input voltage required for regulation at full 150 mA load?
The LD2985AM50R requires an input voltage ≥5.28 V to maintain 5.0 V output at 150 mA, based on its 280 mV maximum dropout specification. Below this, output voltage drops linearly with input; operation below 2.5 V input is prohibited per absolute maximum ratings.
Can the INHIBIT pin be left unconnected?
No. The INHIBIT pin has no internal pull-up or pull-down; leaving it floating causes undefined output behavior. When not actively controlled, it must be tied directly to IN (not VOUT) to ensure guaranteed enable state per datasheet Section 6.5.
Is an external bypass capacitor mandatory for stable operation?
No - the 10 nF bypass capacitor on Pin 4 is optional but required to achieve the specified 30 µVrms output noise. Without it, typical noise rises to ~120 µVrms. Stability is maintained with or without the capacitor, as confirmed in Section 6.1 and Figure 11 of the datasheet.
What is the recommended output capacitor value for 5.0 V operation?
For LD2985AM50R (5.0 V output), the datasheet specifies a minimum 1 µF low-ESR ceramic capacitor on the output (Section 6.3). A 2.2 µF X7R ceramic placed within 12.7 mm of Pin 5 is preferred for improved transient response and margin across temperature.
LD2985AM50R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.575V @ 150mA
- Current - Output:
- 150mA
- Current - Quiescent (Iq):
- 150 µA
- Current - Supply (Max):
- 4 mA
- PSRR:
- 45dB (1kHz)
- Control Features:
- Enable
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LD2985AM50R FAQ
1.How can I place an order for LD2985AM50R through Aetrix?
Please submit a Request for Quotation (RFQ) for LD2985AM50R 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 LD2985AM50R reliable?
The price and inventory of LD2985AM50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD2985AM50R is usually 5 days.
3.What payment methods are accepted for LD2985AM50R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD2985AM50R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD2985AM50R?
LD2985AM50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD2985AM50R 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 LD2985AM50R?
For technical support, including LD2985AM50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD2985AM50R requirements.
6.How does Aetrix verify that LD2985AM50R is sourced from the original manufacturer or authorized distributors?
All LD2985AM50R 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 LD2985AM50R meets industry standards.
7.What is the process for return or replacement of LD2985AM50R?
All LD2985AM50R units undergo pre-shipment inspection (PSI). If there is an issue with LD2985AM50R, 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 LD2985AM50R part is unused and in its original packaging.
Return procedure for LD2985AM50R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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