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Texas Instruments LP38691SDX-3.3
- Part No.:
- LP38691SDX-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 6-WDFN Exposed Pad
- Datasheet:
-
LP38691SDX-3.3.pdf
- Description:
- IC REG LINEAR 3.3V 500MA 6WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,333
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Product details
Overview
LP38691SDX-3.3 from Texas Instruments is a 3.3 V, 500-mA low-dropout CMOS linear regulator in WSON-6 package with PMOS pass transistor, 2% output accuracy (25°C), 250 mV typical dropout at 500 mA (VOUT = 5 V), and stable operation with 1-µF ceramic output capacitor. It delivers precise voltage regulation for battery-powered microcontroller cores in portable instrumentation.
For engineers reviewing the LP38691SDX-3.3 datasheet, LP38691SDX-3.3 pinout, LP38691SDX-3.3 application, or LP38691SDX-3.3 equivalent, key selection considerations include dropout voltage at 3.3 V output, ground pin current under full load, thermal shutdown threshold, enable functionality absence, and WSON-6 thermal pad layout requirements.
Technical Context
The LP38691SDX-3.3 uses a PMOS power transistor architecture eliminating DC base-drive current, enabling ground pin current of only 55 µA at full load across –40°C to 125°C. Its trimmed bandgap reference and internal feedback resistors set fixed 3.3 V output without external components.
No enable pin is present - the device operates continuously when input voltage is within 2.7 V–10 V and exceeds dropout margin. Remote sense (SNS) is implemented but must be tied directly to OUT; it is not functional as a separate control node.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% at 25°C; ensures stable core supply for 3.3-V logic without external resistor network |
| Max Output Current | 500 mA continuous; supports single-core MCU or FPGA I/O bank with margin at ambient ≤85°C |
| Dropout Voltage | 330 mV typical at 500 mA (VOUT = 3.3 V); enables regulation down to VIN ≥ 3.63 V |
| Ground Pin Current | 55 µA typical at full load; minimizes system quiescent loss in always-on battery monitoring circuits |
| Input Voltage Range | 2.7 V to 10 V; compatible with single-cell Li-ion (3.0–4.2 V), dual-cell alkaline (2.7–3.6 V), and 5-V rail inputs |
| Thermal Shutdown | Activates at 160°C junction temperature with 10°C hysteresis; protects against sustained overload in sealed enclosures |
| PSRR | 55 dB at 120 Hz (1 Vp-p ripple); suppresses switching noise from upstream DC/DC converters |
Pinout & Package
LP38691SDX-3.3 is housed in a 3.0 mm × 3.0 mm WSON-6 package with exposed thermal pad (DAP) on bottom for PCB heat sinking. Pin 1 is IN, Pin 2 is GND, Pin 3 is OUT, Pin 4 is SNS, Pin 5 is NC, Pin 6 is IN (dual-input configuration required for full 500-mA rating).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pins 1 & 6) | Input supply connection | Both pins must be connected to same VIN net; each rated for ≤250 mA to meet full 500-mA spec |
| GND (Pin 2) | Regulator ground reference | Low-impedance return path for control circuitry and load current; thermally coupled to die |
| OUT (Pin 3) | Regulated output terminal | Delivers 3.3 V to load; requires 1-µF ceramic capacitor placed ≤1 cm from pin per stability requirement |
| SNS (Pin 4) | Remote output sense input | Must be shorted to OUT; enables remote sensing compensation but unused in standard configurations |
| NC (Pin 5) | No internal connection | Not bonded; must remain unconnected and unstubbed to avoid parasitic coupling |
| DAP (Exposed Pad) | Thermal interface | Requires solder mask-defined thermal pad on PCB; connects to internal ground plane for thermal conduction |
Key Features
| Feature | Design Value |
|---|---|
| Ceramic-capacitor stability | Stable with 1-µF X7R/X5R ceramic output capacitor - eliminates need for high-ESR tantalum or electrolytic types |
| Ultra-low ground current | 55 µA typical at 500-mA load - reduces system standby power by >90% vs bipolar LDOs |
| Wide temperature range | Specified from –40°C to +125°C - suitable for automotive cabin and industrial edge controller environments |
| Foldback current limiting | Reduces output current to ~350 mA when VIN–VOUT > 5 V - prevents thermal runaway during input overvoltage |
| Thermal overload protection | Shuts down at 160°C junction temp with 10°C hysteresis - provides self-recovery under transient overload |
Applications
| Portable Medical Sensors | Industrial PLC I/O Modules |
|---|---|
Use Scenario: Powering ultra-low-power ADCs and BLE transceivers in handheld glucose meters with coin-cell or LiPo backup. IC Role / Device Role / Timing Role: Primary 3.3-V supply for analog front-end and wireless SoC; no timing function. Use Value: 55 µA ground current extends battery life beyond 12 months; 1-µF ceramic compatibility reduces BOM count and board area. |
Use Scenario: Regulating 3.3 V for digital isolator side and microcontroller in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Fixed-output LDO delivering clean rail to isolated communication interfaces and real-time MCU cores. Use Value: 55 dB PSRR at 120 Hz rejects noise from 24-V DC/DC converters; –40°C to 125°C rating ensures operation in uncooled cabinets. |
| Automotive Body Control Units | Test & Measurement Handhelds |
Use Scenario: Supplying 3.3 V to CAN transceivers and LIN controllers in door module ECUs operating across battery voltage swings. IC Role / Device Role / Timing Role: Load-regulated voltage source maintaining stable logic levels despite 6–16 V input variation. Use Value: 330 mV dropout at 500 mA allows regulation down to 3.63 V input - supports cold-crank operation to 6.5 V battery minimum. |
Use Scenario: Providing precision 3.3-V rail to high-resolution SAR ADCs and FPGA configuration memory in portable oscilloscopes. IC Role / Device Role / Timing Role: Low-noise analog supply decoupled from digital switching domains via ceramic capacitor filtering. Use Value: 0.7 µV/√Hz output noise preserves SNR in 16-bit data acquisition; WSON thermal pad enables compact heatsinking in sealed chassis. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-dropout linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLC7603-33IDBVR | 3.3 V fixed, 300 mA max, SOT-23-5, 400 mV dropout at 300 mA | Lower current rating; no SNS pin; smaller footprint but higher thermal resistance | Select when board space is critical and load < 300 mA; verify thermal derating at 85°C ambient |
| TPS7A2033PDQNR | 3.3 V fixed, 300 mA, WSON-6, 170 mV dropout at 300 mA, 25 µA IQ | Lower dropout and quiescent current, but reduced max current and no foldback limiting | Prefer for ultra-low-IQ battery systems with < 300 mA loads; avoid where input overvoltage risk exists |
Compared with TLC7603-33IDBVR and TPS7A2033PDQNR, LP38691SDX-3.3 offers higher output current (500 mA vs ≤300 mA), integrated foldback current limiting for input overvoltage resilience, and proven stability with minimal 1-µF ceramic output capacitance - making it optimal for cost-sensitive, thermally constrained 3.3-V power rails requiring robustness over raw efficiency.
Availability
LP38691SDX-3.3 is available at Aetrix Electronics and suitable for portable instrumentation, industrial PLC I/O modules, and automotive body control units requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LP38691SDX-3.3 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
Texas Instruments is a global semiconductor company designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and personal electronics markets.
The LP3869x family was developed specifically for portable, battery-powered digital systems requiring fast start-up, tight output tolerance, and ceramic-capacitor compatibility - targeting notebook computers, hard disk drives, and handheld instrumentation.
FAQ
Does LP38691SDX-3.3 have an enable pin?
No, LP38691SDX-3.3 does not include an enable (EN) pin. It is a permanently enabled regulator - operation begins whenever input voltage exceeds 2.7 V and the dropout condition is met. The LP38693 variant includes EN functionality, but LP38691SDX-3.3 relies on input rail control for on/off sequencing. This simplifies design for always-on subsystems where external enable logic is unnecessary.
What is the minimum input voltage required for LP38691SDX-3.3 to regulate 3.3 V?
The minimum input voltage for LP38691SDX-3.3 to maintain regulation is determined by its dropout voltage: 330 mV typical at 500 mA load. Therefore, VIN must be ≥ 3.63 V to sustain 3.3 V output under full load. At lighter loads (e.g., 100 mA), dropout drops to ~65 mV, allowing regulation down to ~3.37 V. Input must also exceed the absolute minimum 2.7 V specified for internal circuit functionality.
Can LP38691SDX-3.3 be used with a 1-µF output capacitor?
Yes, LP38691SDX-3.3 is explicitly designed and characterized for stability with a single 1-µF ceramic output capacitor - no ESR requirements or damping networks needed. This is confirmed in the datasheet's "Typical Application Circuits" and "Electrical Characteristics" sections. Using X5R or X7R dielectrics is recommended to maintain capacitance across temperature and bias.
How should the exposed thermal pad (DAP) of LP38691SDX-3.3 be connected?
The exposed thermal pad (DAP) on the underside of the LP38691SDX-3.3 WSON-6 package must be soldered to a dedicated PCB copper pour connected to the GND net. Per TI's AN-1187 and datasheet Section 11.3, this pad serves as the primary thermal conduction path - omitting it increases RθJA by >20°C/W. A minimum 2×2 array of thermal vias (0.3-mm diameter, spaced ≤1 mm apart) should connect the pad to inner-layer ground planes.
Is LP38691SDX-3.3 suitable for automotive applications?
LP38691SDX-3.3 is not AEC-Q100 qualified. While it operates across –40°C to +125°C and meets many automotive environmental requirements, only the LP38691-Q1 variant is certified to AEC-Q100 Grade 1. For production automotive ECUs, LP38691-Q1SDX-3.3 must be used. LP38691SDX-3.3 may be considered for prototyping or non-safety-critical aftermarket devices where qualification is not mandated.
LP38691SDX-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 6-WDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.55V @ 500mA
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 55 µA
- Current - Supply (Max):
- 100 µA
- PSRR:
- 55dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 6-WSON (3x3)
LP38691SDX-3.3 FAQ
1.How can I place an order for LP38691SDX-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LP38691SDX-3.3 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 LP38691SDX-3.3 reliable?
The price and inventory of LP38691SDX-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP38691SDX-3.3 is usually 5 days.
3.What payment methods are accepted for LP38691SDX-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP38691SDX-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP38691SDX-3.3?
LP38691SDX-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP38691SDX-3.3 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 LP38691SDX-3.3?
For technical support, including LP38691SDX-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP38691SDX-3.3 requirements.
6.How does Aetrix verify that LP38691SDX-3.3 is sourced from the original manufacturer or authorized distributors?
All LP38691SDX-3.3 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 LP38691SDX-3.3 meets industry standards.
7.What is the process for return or replacement of LP38691SDX-3.3?
All LP38691SDX-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LP38691SDX-3.3, 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 LP38691SDX-3.3 part is unused and in its original packaging.
Return procedure for LP38691SDX-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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