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STMicroelectronics LD2985AM18R
- Part No.:
- LD2985AM18R
- Manufacturer:
- STMicroelectronics
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LD2985AM18R.pdf
- Description:
- IC REG LINEAR 1.8V 150MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,566
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Product details
Overview
LD2985AM18R from STMicroelectronics is a 150 mA fixed-output low-dropout linear voltage regulator delivering 1.8 V with 280 mV dropout at 150 mA, 30 µVrms output noise, and logic-controlled inhibit shutdown. It operates across –40 °C to 125 °C and targets battery-powered portable electronics requiring ultra-low quiescent current (80 µA at no load) and precise low-noise power.
For engineers reviewing the LD2985AM18R datasheet, LD2985AM18R pinout, LD2985AM18R application, or LD2985AM18R equivalent, key selection criteria include dropout performance at light load, inhibit input logic thresholds (VIL = 0.15 V), bypass-capacitor–enabled noise reduction, and SOT23-5L thermal resistance (RthJA = 255 °C/W).
Technical Context
The LD2985AM18R uses a PNP pass transistor architecture enabling ultra-low dropout-just 7 mV at 1 mA-and supports stable operation with ceramic output capacitors as low as 2.2 µF for 1.8 V output. Its internal feedback resistors (42.6 kΩ / 51.15 kΩ) set the fixed 1.8 V output and enable reverse-current blocking when VOUT > VIN.
Inhibit control is TTL-compatible: pulling Pin 3 ≤ 0.15 V disables regulation and reduces quiescent current to < 1 µA; leaving it unconnected is invalid. The Bypass pin (Pin 4) accepts a 10 nF capacitor to ground to reduce output noise to 30 µVrms (300 Hz–50 kHz).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.8 V ±2.5% over –40 °C to 125 °C; ensures stable core supply for 1.8 V logic rails. |
| Dropout Voltage | 280 mV at 150 mA; enables regulation down to VIN = 2.08 V, critical for single-cell Li-ion or Li-poly systems. |
| Quiescent Current | 80 µA at no load; extends battery life in standby mode without external biasing. |
| Output Noise | 30 µVrms (300 Hz–50 kHz) with 10 nF bypass cap; meets low-noise analog/RF supply requirements. |
| Inhibit Threshold | VIL = 0.15 V max; allows direct interface with 1.8 V GPIO without level-shifting. |
| Thermal Resistance | RthJA = 255 °C/W (SOT23-5L); limits max junction temperature to 125 °C at 150 mA with minimal PCB copper. |
| Operating Temp | –40 °C to 125 °C junction; qualified for automotive cabin and industrial edge-node environments. |
Pinout & Package
SOT23-5L package: 5-pin surface-mount, 1.45 mm height, 2.95 mm × 1.60 mm footprint, exposed pad not present. RoHS-compliant, ECOPACK2 rated.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Input supply connection | Accepts 2.5–16 V DC; requires ≥1 µF ceramic capacitor within 12.7 mm of pin for stability. |
| 2 GND | Power ground reference | Low-impedance return path for IN, OUT, INHIBIT, and Bypass; must connect to clean analog ground plane. |
| 3 INHIBIT | Active-low enable control | TTL-compatible; <0.15 V disables regulator (IQ < 1 µA); must not float; tie to VIN if unused. |
| 4 Bypass | Noise-reduction node | Connects 10 nF ceramic capacitor to GND to lower output noise from ~100 µVrms to 30 µVrms. |
| 5 OUT | Regulated 1.8 V output | Delivers up to 150 mA; requires 2.2 µF ceramic capacitor (low ESR) within 12.7 mm for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low dropout | 7 mV at 1 mA load enables operation with near-dead batteries or stacked coin cells. |
| Sub-µA shutdown | <1 µA quiescent current in inhibit mode extends shelf life in always-on IoT sensors. |
| Bypass-enabled noise reduction | 30 µVrms noise with 10 nF cap meets ADC reference and RF LDO requirements. |
| Reverse-current blocking | No body diode conduction; output-to-input reverse current limited to 160 µA at VREV. |
| Fixed 1.8 V output | Factory-trimmed resistor network eliminates external feedback components and layout sensitivity. |
Applications
| Smartphone Baseband Power | Wearable Sensor Node |
|---|---|
|
Use Scenario: Supplying 1.8 V core voltage to application processors and memory interfaces in compact smartphones. IC Role / Device Role / Timing Role: Local LDO providing clean, low-noise power to digital baseband ICs during burst-mode transmission. Use Value: 280 mV dropout preserves headroom under dynamic load; 30 µVrms noise prevents bit errors in high-speed DDR I/O. |
Use Scenario: Powering ultra-low-power accelerometers, temperature sensors, and BLE SoCs in fitness trackers. IC Role / Device Role / Timing Role: Primary regulated supply enabling sub-10 µA sleep current via INHIBIT control. Use Value: 80 µA no-load IQ and <1 µA inhibit mode extend coin-cell lifetime beyond 12 months. |
| Digital Camera Image Sensor Bias | Industrial PLC I/O Module |
|
Use Scenario: Delivering low-noise 1.8 V bias to CMOS image sensor analog front-end circuits. IC Role / Device Role / Timing Role: Dedicated LDO isolating sensor analog supply from noisy digital domains. Use Value: 30 µVrms noise with bypass cap suppresses fixed-pattern noise in 12-bit image capture. |
Use Scenario: Providing isolated 1.8 V logic supply for FPGA configuration and serial interface ICs in harsh industrial cabinets. IC Role / Device Role / Timing Role: Robust local regulator handling wide input transients (up to 16 V) and extended temperature cycling. Use Value: –40 °C to 125 °C operation and 255 °C/W RthJA ensure reliability without heatsinking in confined enclosures. |
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 |
|---|---|---|---|
| TPS7A0518PDBVR | Lower IQ (25 µA typ.), but higher dropout (300 mV at 150 mA); no bypass pin for noise reduction. | Lacks dedicated noise-reduction path; unsuitable where <35 µVrms is required. | Select if lowest quiescent current dominates; avoid for precision analog or RF supply. |
| MCP1700T-1802E/TT | Higher dropout (550 mV at 150 mA); no inhibit function; only 250 mA max output. | Requires external enable circuitry for shutdown; cannot achieve <1 µA off-state. | Select for cost-sensitive, non-battery applications where dropout and noise are less critical. |
Compared with TPS7A0518PDBVR and MCP1700T-1802E/TT, the LD2985AM18R uniquely combines sub-10 mV dropout at light load, integrated bypass noise filtering, and guaranteed <1 µA inhibit current-making it optimal for space-constrained, battery-operated systems demanding both ultra-low power and ultra-low noise.
Availability
LD2985AM18R is available at Aetrix Electronics and suitable for smartphone baseband power, wearable sensor nodes, digital camera image sensor bias, and industrial PLC I/O modules requiring stable component supply across automotive and industrial temperature ranges.
Supply support for LD2985AM18R 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 devices for industrial, automotive, and consumer markets.
The LD2985 series belongs to ST's high-performance LDO portfolio, engineered specifically for ultra-low-noise, ultra-low-dropout power delivery in portable and battery-critical applications.
FAQ
What is the minimum input voltage required for regulation at 150 mA output?
The LD2985AM18R requires VIN ≥ VOUT + VDROP. At 150 mA, typical dropout is 280 mV, so minimum input is 1.8 V + 0.28 V = 2.08 V. Absolute minimum operating input voltage per datasheet is 2.5 V to guarantee all specifications across temperature.
Can the INHIBIT pin be left floating?
No. The INHIBIT pin has no internal pull-up or pull-down. Leaving it floating risks undefined behavior and potential device malfunction. If not used, it must be tied directly to VIN to maintain regulation; if used, drive it to ≤0.15 V for shutdown or ≥2 V for enable.
Is an external capacitor required on the Bypass pin?
Yes-only if 30 µVrms output noise is required. The datasheet specifies a 10 nF ceramic capacitor between Bypass (Pin 4) and GND to achieve that spec. Without it, typical noise rises to ~100 µVrms, which may affect sensitive analog circuits.
Does the LD2985AM18R support ceramic output capacitors?
Yes-specifically designed for ceramic output capacitors. For 1.8 V output, minimum recommended value is 2.2 µF with low ESR. Tantalum capacitors are possible but not recommended due to size, cost, and ESR variability over temperature.
LD2985AM18R 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):
- 1.8V
- 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
LD2985AM18R FAQ
1.How can I place an order for LD2985AM18R through Aetrix?
Please submit a Request for Quotation (RFQ) for LD2985AM18R 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 LD2985AM18R reliable?
The price and inventory of LD2985AM18R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD2985AM18R is usually 5 days.
3.What payment methods are accepted for LD2985AM18R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD2985AM18R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD2985AM18R?
LD2985AM18R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD2985AM18R 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 LD2985AM18R?
For technical support, including LD2985AM18R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD2985AM18R requirements.
6.How does Aetrix verify that LD2985AM18R is sourced from the original manufacturer or authorized distributors?
All LD2985AM18R 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 LD2985AM18R meets industry standards.
7.What is the process for return or replacement of LD2985AM18R?
All LD2985AM18R units undergo pre-shipment inspection (PSI). If there is an issue with LD2985AM18R, 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 LD2985AM18R part is unused and in its original packaging.
Return procedure for LD2985AM18R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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