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STMicroelectronics LD1117STR
- Part No.:
- LD1117STR
- Manufacturer:
- STMicroelectronics
- Package:
- TO-261-4, TO-261AA
- Datasheet:
-
LD1117STR.pdf
- Description:
- IC REG LIN POS ADJ 800MA SOT223
- Quantity:
- Payment:
- Shipping:
Inventory:4,749
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Product details
Overview
LD1117STR from STMicroelectronics is a fixed-output, low-dropout linear voltage regulator delivering up to 800 mA at 3.3 V with 1.2 V typical dropout at 100 mA, ±1 % output tolerance at 25 °C, and 75 dB supply voltage rejection - used in embedded power rails for microcontrollers, sensors, and industrial I/O modules.
For engineers reviewing the LD1117STR datasheet, LD1117STR pinout, LD1117STR application, or LD1117STR equivalent, key selection criteria include dropout voltage under load, thermal resistance in SOT-223, output tolerance across temperature, and minimum 10 µF output capacitor requirement for stability.
Technical Context
The LD1117STR integrates an NPN pass transistor enabling high efficiency by routing quiescent current primarily into the load rather than ground. Its internal bandgap reference and error amplifier maintain regulation across input voltages from 4.75 V to 15 V and output loads from 2 mA to 800 mA.
Thermal protection and current limiting are implemented on-die, with junction-to-case thermal resistance of 15 °C/W in SOT-223. The device operates over –40 °C to +125 °C (C-grade) and requires only a single 10 µF ceramic or tantalum output capacitor for stability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V, ±1 % tolerance at 25 °C ensures precise MCU core/logic rail compliance |
| Max Output Current | 800 mA continuous - supports moderate-power peripherals without external boost stages |
| Dropout Voltage | 1.1 V typ. at 800 mA - enables operation from 4.4 V input while maintaining 3.3 V output |
| Supply Rejection | 75 dB typ. at 120 Hz - suppresses ripple from upstream switching converters |
| Thermal Resistance | 15 °C/W junction-to-case (SOT-223) - allows ~7 W dissipation with heatsinked PCB copper |
| Output Capacitor | 10 µF minimum - standard value compatible with low-ESR ceramic capacitors |
| Quiescent Current | 5–10 mA - scales with input voltage, not load, enabling predictable idle power |
Pinout & Package
LD1117STR is supplied in SOT-223 package with exposed thermal pad connected internally to VOUT. Pin 1 = IN, Pin 2 = OUT, Pin 3 = GND, Pin 4 = TAB/VOUT (electrically tied to Pin 2).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (IN) | Input voltage supply | Accepts 4.75–15 V DC; must be decoupled within 1 cm of pin with ≥1 µF ceramic capacitor |
| Pin 2 (OUT) | Regulated output | Delivers stable 3.3 V; connects directly to load and 10 µF output capacitor |
| Pin 3 (GND) | Ground reference | Low-impedance return path for feedback and load current; separate trace from power ground recommended |
| Pin 4 (TAB) | Thermal pad / VOUT | Internally bonded to VOUT; must be soldered to ≥2 cm² copper pour for thermal performance |
Key Features
| Feature | Design Value |
|---|---|
| Low dropout | 1.1 V max at 800 mA enables use with 5 V bus or Li-ion battery (3.7 V nominal) |
| Output accuracy | ±1 % at 25 °C and ±2 % over full –40 °C to +125 °C range ensures reliable logic-level margin |
| Thermal shutdown | Activates at ~165 °C junction temperature and auto-recovers after cooldown |
| Current limit | Internally set to ~1.3 A peak - protects against short-circuit without external foldback |
| Stability | Guaranteed with 10 µF output capacitor; no ESR requirements simplify BOM |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
Use Scenario: Powering isolated digital input buffers and CAN transceiver logic rails in DIN-rail mounted controllers. IC Role / Device Role / Timing Role: Primary 3.3 V LDO supplying FPGA configuration I/O banks and optocoupler interface circuitry. Use Value: 1.1 V dropout allows direct regulation from 5 V backplane, reducing heat vs. older 2.5 V dropout regulators. |
Use Scenario: Providing clean 3.3 V to microcontroller peripherals (LIN transceivers, EEPROM, sensors) in door module ECUs. IC Role / Device Role / Timing Role: Post-regulator following a 5 V buck converter, rejecting switching noise before sensitive analog inputs. Use Value: 75 dB SVR at 120 Hz attenuates buck ripple, eliminating need for additional LC filtering. |
| Medical Patient Monitor Front-End | POS Terminal Secure Element Supply |
Use Scenario: Biasing analog front-end amplifiers and ADC reference circuits in portable vital sign monitors. IC Role / Device Role / Timing Role: Low-noise 3.3 V source for precision signal chain components requiring <100 µV RMS noise. Use Value: 100 µV output noise (10 Hz–10 kHz) meets EN 60601-1 EMC immunity thresholds for clinical devices. |
Use Scenario: Supplying secure crypto co-processor and smart card interface ICs in payment terminals. IC Role / Device Role / Timing Role: Tamper-resistant regulated rail with thermal/current protection to prevent fault injection attacks. Use Value: On-chip thermal shutdown prevents sustained overtemperature during malicious power glitching attempts. |
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 |
|---|---|---|---|
| AMS1117-3.3 | Higher dropout (1.2 V min at 800 mA), ±2 % tolerance over temperature, no guaranteed C-grade (-40 °C to +125 °C) option | Suitable for commercial-grade consumer devices but not automotive or extended-temp industrial use | Select when cost sensitivity outweighs thermal performance and temp range requirements |
| MCP1700T-3302E/MB | Lower IQ (2 µA), 250 mA max output, SOT-23 package - not a drop-in replacement for 800 mA loads | Targeted at ultra-low-power battery applications, not high-current embedded systems | Choose only for sub-100 mA loads where quiescent current dominates system energy budget |
Compared with AMS1117-3.3 and MCP1700T-3302E/MB, LD1117STR provides higher current capability with tighter tolerance and wider operating temperature range, making it suitable for demanding industrial and automotive power rails where reliability and thermal headroom are critical.
Availability
LD1117STR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical monitoring equipment, and point-of-sale terminals requiring stable component supply with long lifecycle support.
Supply support for LD1117STR 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, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.
LD1117STR belongs to ST's high-reliability linear regulator product line, engineered specifically for robust, low-noise power delivery in harsh environments with wide temperature operation and integrated protection.
FAQ
What is the minimum input voltage required for LD1117STR to regulate 3.3 V at 800 mA?
The minimum input voltage is 4.4 V, calculated as 3.3 V output plus maximum dropout voltage of 1.1 V at 800 mA. Below this, regulation fails and output drops linearly with input. Input must also remain within absolute maximum rating of 15 V.
Can LD1117STR replace LM1117-3.3 in existing designs?
Yes, LD1117STR is pin-compatible with LM1117-3.3 in SOT-223 and offers identical pinout, electrical behavior, and footprint. It improves upon LM1117 with tighter output tolerance (±1 % vs. ±2 %) and higher guaranteed current (800 mA vs. 800 mA typical).
Is an input capacitor required for stable operation?
An input capacitor is strongly recommended: ≥1 µF ceramic placed within 1 cm of the IN pin reduces high-frequency noise and prevents oscillation due to trace inductance. While not strictly mandatory per datasheet, omission risks instability under fast load transients.
How does thermal performance differ between SOT-223 and DPAK packages?
SOT-223 has RthJC = 15 °C/W and RthJA = 110 °C/W; DPAK offers lower RthJC = 8 °C/W but similar RthJA = 100 °C/W. In PCB-constrained layouts, DPAK delivers better junction-to-heatsink transfer, while SOT-223 relies more on copper pour area for cooling.
LD1117STR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-261-4, TO-261AA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 15V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 15V
- Voltage Dropout (Max):
- 1.2V @ 800mA
- Current - Output:
- 800mA
- Current - Quiescent (Iq):
- 5 mA
- Current - Supply (Max):
- -
- PSRR:
- 75dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-223
LD1117STR FAQ
1.How can I place an order for LD1117STR through Aetrix?
Please submit a Request for Quotation (RFQ) for LD1117STR 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 LD1117STR reliable?
The price and inventory of LD1117STR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD1117STR is usually 5 days.
3.What payment methods are accepted for LD1117STR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD1117STR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD1117STR?
LD1117STR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD1117STR 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 LD1117STR?
For technical support, including LD1117STR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD1117STR requirements.
6.How does Aetrix verify that LD1117STR is sourced from the original manufacturer or authorized distributors?
All LD1117STR 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 LD1117STR meets industry standards.
7.What is the process for return or replacement of LD1117STR?
All LD1117STR units undergo pre-shipment inspection (PSI). If there is an issue with LD1117STR, 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 LD1117STR part is unused and in its original packaging.
Return procedure for LD1117STR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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