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STMicroelectronics LD2985AM285R
- Part No.:
- LD2985AM285R
- Manufacturer:
- STMicroelectronics
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LD2985AM285R.pdf
- Description:
- IC REG LIN 2.85V 150MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,286
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Product details
Overview
LD2985AM285R from STMicroelectronics is a 150 mA fixed-output low-dropout linear voltage regulator with 2.85 V nominal output, ultra-low dropout (280 mV at 150 mA), 30 µVrms output noise, and logic-controlled inhibit function on Pin 3. It operates across –40 °C to 125 °C and uses a 10 nF bypass capacitor to achieve low-noise performance in battery-powered portable electronics.
For engineers reviewing the LD2985AM285R datasheet, LD2985AM285R pinout, LD2985AM285R application, or LD2985AM285R equivalent, this device is selected for precision low-noise local regulation where quiescent current (<1 µA in shutdown), thermal stability, and TTL-compatible enable control are critical design requirements.
Technical Context
The LD2985AM285R integrates a PNP pass transistor architecture enabling ultra-low dropout operation down to 7 mV at 1 mA load. Its internal feedback network sets a precise 2.85 V output with ±1.2% tolerance over temperature and line variations.
It features a dedicated INHIBIT pin (Pin 3) with TTL-compatible thresholds (VIL ≤ 0.15 V, VIH ≥ 2 V) and <5 µA input leakage, allowing direct interfacing with microcontroller GPIOs for system-level power gating without external level-shifting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 2.85 V ±1.2% (ensures stable core supply for 2.8 V–3.0 V logic rails) |
| Dropout Voltage | 280 mV at 150 mA (enables regulation from 3.13 V input when VOUT = 2.85 V) |
| Quiescent Current | 80 µA at no load; <1 µA in inhibit mode (extends battery life in standby) |
| Output Noise | 30 µVrms (B = 300 Hz–50 kHz, with 10 nF bypass cap; suitable for RF/analog circuitry) |
| Supply Rejection | 45 dB at 1 kHz (rejects switching noise from upstream DC/DC converters) |
| Operating Temp | –40 °C to +125 °C junction (supports automotive cabin and industrial edge node deployment) |
| Max Output Current | 150 mA continuous (powers single-core MCUs, sensors, or RF front-ends) |
Pinout & Package
SOT23-5L package: 5-pin surface-mount, 1.3 mm height, 2.95 mm × 1.60 mm footprint, exposed pad not present, RoHS-compliant ECOPACK2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Input voltage supply | Accepts 2.5–16 V DC; requires ≥1 µF ceramic capacitor within 12.7 mm of pin |
| 2 (GND) | Ground reference | Common return for input, output, bypass, and inhibit paths; must connect to clean analog ground plane |
| 3 (INHIBIT) | Logic shutdown control | TTL-compatible enable: <0.15 V disables regulator (IQ <1 µA); ≥2 V enables operation |
| 4 (BYPASS) | Noise reduction terminal | Connects 10 nF ceramic capacitor to GND to reduce output noise to 30 µVrms |
| 5 (OUT) | Regulated output | Delivers 2.85 V ±1.2% at up to 150 mA; requires 2.2 µF ceramic cap (low-ESR) for stability |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low dropout | 7 mV at 1 mA load enables operation from near-output voltages - critical for coin-cell or single Li-ion systems |
| Sub-µA shutdown | Inhibit-driven shutdown draws <1 µA total, reducing system standby power by >99% vs. active mode |
| Low-noise architecture | 30 µVrms noise with 10 nF bypass cap meets LDO requirements for ADC references and RF synthesizers |
| Thermal protection | Internal thermal foldback limits junction temperature to 125 °C - no external thermal sensor required |
| Reverse-current blocking | No body diode between IN and OUT prevents backfeed when VOUT > VIN, eliminating need for external blocking diodes |
Applications
| Portable Medical Sensors | Wearable Biometric Monitors |
|---|---|
Use Scenario: Continuous ECG/PPG signal acquisition in patch-style monitors powered by CR2032 or thin-film batteries. IC Role / Device Role / Timing Role: Local 2.85 V LDO supplying analog front-end and low-power MCU, with inhibit synchronized to measurement duty cycle. Use Value: 80 µA quiescent current and <1 µA shutdown extend battery life to >6 months; 30 µVrms noise ensures <12-bit ENOB in ADC path. |
Use Scenario: Real-time heart rate and SpO₂ monitoring in wrist-worn devices with ambient light rejection. IC Role / Device Role / Timing Role: Precision 2.85 V rail for optical sensor array and BLE SoC, enabled only during sampling windows via GPIO-controlled INHIBIT. Use Value: 280 mV dropout allows operation down to 3.13 V input from aging LiPo cells; reverse-current blocking prevents sensor leakage from draining battery. |
| Industrial IoT Edge Nodes | Automotive Cabin Controllers |
Use Scenario: Battery-backed environmental sensor node (temp/humidity/pressure) deployed in remote locations with 10-year lifetime target. IC Role / Device Role / Timing Role: Primary 2.85 V regulator for ultra-low-power MCU and digital sensors, disabled between wake-up intervals using INHIBIT. Use Value: –40 °C to +125 °C rating supports unheated outdoor enclosures; 45 dB SVR suppresses noise from shared 12 V vehicle bus-derived input. |
Use Scenario: Power management for touch-button control modules behind automotive center console displays. IC Role / Device Role / Timing Role: Local 2.85 V supply for capacitive touch controller IC, enabled only when ignition is ON via CAN-linked MCU GPIO. Use Value: TTL-compatible INHIBIT eliminates level-shifter cost; thermal shutdown protects against sustained high-ambient under-dash conditions. |
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 |
|---|---|---|---|
| Torex XC6219B285MR-G | 2.85 V output, 150 mA, 250 mV dropout at 150 mA, but no dedicated BYPASS pin - noise is 45 µVrms without external filtering | Lacks integrated noise-reduction path; requires larger output cap or external RC filter for same noise performance | Select if board space prohibits 10 nF bypass cap placement near IC, and 45 µVrms noise is acceptable |
| Diodes Inc. AP2204K-2.8TRG1 | 2.8 V output (not 2.85 V), 150 mA, 350 mV dropout at 150 mA, 60 µVrms noise, no BYPASS pin, inhibit threshold VIL = 0.4 V (less noise-immune) | 0.05 V output offset may affect 2.85 V-tolerant logic; higher noise and looser inhibit threshold limit use in noisy environments | Select only for cost-sensitive designs where 2.8 V output suffices and system EMI margin is >200 mV |
Compared with XC6219B285MR-G and AP2204K-2.8TRG1, LD2985AM285R delivers tighter output accuracy (±1.2% vs. ±2%), lower noise (30 vs. 45/60 µVrms), and a dedicated BYPASS pin enabling predictable noise suppression - making it optimal for signal-chain-critical applications.
Availability
LD2985AM285R is available at Aetrix Electronics and suitable for portable medical sensors, wearable biometric monitors, industrial IoT edge nodes, and automotive cabin controllers requiring stable component supply across extended temperature and long-lifecycle programs.
Supply support for LD2985AM285R 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 analog, MCU, power, and sensing solutions for industrial, automotive, and consumer markets.
The LD2985 series belongs to ST's precision low-noise LDO portfolio, engineered specifically for battery-powered portable electronics demanding sub-µA shutdown, ultra-low dropout, and integrated noise mitigation without external compensation.
FAQ
What is the minimum input voltage required for regulation at 2.85 V output?
The LD2985AM285R maintains regulation when input voltage exceeds output voltage by its dropout voltage. At 150 mA load, dropout is 280 mV, so minimum input is 3.13 V. At 1 mA load, dropout drops to 7 mV, permitting regulation from 2.857 V - enabling operation from nearly depleted single-cell Li-ion or alkaline sources.
Can the INHIBIT pin be left floating?
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 (to force ON) or to GND (to force OFF). A weak pull-up to IN is acceptable only if system timing permits guaranteed logic-high startup.
Is an external bypass capacitor mandatory for stable operation?
The 10 nF bypass capacitor on Pin 4 is not required for basic regulation stability but is mandatory to achieve the specified 30 µVrms output noise. Without it, noise rises to ~120 µVrms. The capacitor must be a high-quality ceramic type placed within 2 mm of Pin 4 and GND to preserve high-frequency noise suppression.
Does LD2985AM285R support reverse-current protection?
Yes. Unlike NPN-based LDOs, the LD2985AM285R uses a PNP pass element without an intrinsic body diode. When VOUT exceeds VIN, reverse current is limited to ~160 µA through internal feedback resistors - eliminating need for external blocking diodes in backup-supply or hot-swap configurations.
LD2985AM285R 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):
- 2.85V
- 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
LD2985AM285R FAQ
1.How can I place an order for LD2985AM285R through Aetrix?
Please submit a Request for Quotation (RFQ) for LD2985AM285R 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 LD2985AM285R reliable?
The price and inventory of LD2985AM285R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD2985AM285R is usually 5 days.
3.What payment methods are accepted for LD2985AM285R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD2985AM285R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD2985AM285R?
LD2985AM285R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD2985AM285R 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 LD2985AM285R?
For technical support, including LD2985AM285R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD2985AM285R requirements.
6.How does Aetrix verify that LD2985AM285R is sourced from the original manufacturer or authorized distributors?
All LD2985AM285R 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 LD2985AM285R meets industry standards.
7.What is the process for return or replacement of LD2985AM285R?
All LD2985AM285R units undergo pre-shipment inspection (PSI). If there is an issue with LD2985AM285R, 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 LD2985AM285R part is unused and in its original packaging.
Return procedure for LD2985AM285R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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