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Texas Instruments LP38691SD-1.8/NOPB
- Part No.:
- LP38691SD-1.8/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 6-WDFN Exposed Pad
- Datasheet:
-
LP38691SD-1.8/NOPB.pdf
- Description:
- IC REG LINEAR 1.8V 500MA 6WSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,520
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Product details
Overview
LP38691SD-1.8/NOPB from Texas Instruments is a 500-mA, 1.8-V fixed-output low-dropout CMOS linear regulator in a 6-pin WSON package with exposed thermal pad. It features 2% output accuracy at 25°C, 250 mV typical dropout at 500 mA (VOUT = 5 V), 55 µA ground pin current at full load, and stable operation with only 1-µF ceramic output capacitance. It is used in space-constrained battery-powered systems requiring precise, low-noise voltage regulation.
For engineers reviewing the LP38691SD-1.8/NOPB datasheet, LP38691SD-1.8/NOPB pinout, LP38691SD-1.8/NOPB application, or LP38691SD-1.8/NOPB equivalent, key selection considerations include dropout performance at 1.8 V output, thermal behavior in WSON packages, remote sensing capability (SNS pin), quiescent current under light load, and compatibility with ultra-low-ESR ceramic capacitors without external compensation.
Technical Context
The LP38691SD-1.8/NOPB uses a PMOS pass transistor architecture enabling near-zero ground pin current independent of load, input voltage, or temperature - critical for battery runtime. Its trimmed bandgap reference and internal feedback network deliver 2% output tolerance across –40°C to 125°C, with load regulation of ≤5%/A and line regulation of ≤0.1%/V over full operating conditions.
No enable pin is integrated; the device operates continuously when powered. Thermal shutdown activates at ~160°C junction temperature with ~10°C hysteresis, and foldback current limiting engages based on VIN–VOUT differential - limiting to ~350 mA above 5 V differential and ~850 mA below 4 V differential.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.8 V ±2% (25°C); ensures stable core supply for low-voltage microcontrollers and FPGAs. |
| Max Output Current | 500 mA continuous; supports moderate-power digital loads without external heat sinking in WSON package. |
| Dropout Voltage | 250 mV typical at 500 mA (for 5 V output); at 1.8 V output, minimum input is ~2.05 V @ 500 mA per datasheet curves. |
| Ground Pin Current | 55 µA typical at full load; enables high efficiency at light loads and extends battery life in standby modes. |
| Input Voltage Range | 2.7 V to 10 V; compatible with single-cell Li-ion (with boost), dual-cell alkaline, or 3.3/5 V system rails. |
| Output Noise | 0.7 µV/√Hz (10 Hz–10 kHz, VOUT = 3.3 V); low noise preserves signal integrity in analog-sensitive applications. |
| Ripple Rejection | 55 dB at 120 Hz; suppresses switching noise from upstream DC/DC converters feeding the LDO input. |
Pinout & Package
The LP38691SD-1.8/NOPB is housed in a 6-pin WSON (NGG) package measuring 3.00 mm × 3.00 mm with an exposed thermal pad (DAP) on the bottom for enhanced heat dissipation. The DAP must be soldered to a PCB copper plane to meet thermal specifications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pins 1, 6) | Input supply connection | Both pins must be tied together externally; each rated for up to 250 mA, enabling robust current handling in compact layout. |
| OUT (Pin 3) | Regulated output node | Delivers stable 1.8 V; connects directly to load and output capacitor; low-impedance path required for transient response. |
| SNS (Pin 5) | Remote output voltage sense | Must be connected to OUT; enables remote sensing to compensate for PCB trace IR drop in high-current or long-trace applications. |
| GND (Pin 2) | Power and signal reference | Primary ground return; low-inductance connection to PCB ground plane essential for stability and noise control. |
| DAP (Exposed Pad) | Thermal interface | Electrically connected to GND; soldering to ≥100 mm² copper area reduces RθJB to 24.9°C/W for improved thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Stable with 1-µF ceramic output cap | Eliminates need for large tantalum or electrolytic capacitors - reduces board area and cost in portable designs. |
| 2% output accuracy over temperature | Ensures reliable operation of 1.8-V I/O and core logic across industrial temperature range (–40°C to 125°C). |
| 55 µA ground current at full load | Minimizes wasted current in battery-powered systems where GND path loss directly impacts runtime. |
| PMOS pass transistor architecture | Removes base-drive current dependency - ground current stays constant regardless of load, input, or temp. |
| Thermal shutdown with hysteresis | Protects against sustained overload; 10°C hysteresis prevents oscillation during thermal recovery in enclosed environments. |
Applications
| Portable Medical Sensors | Notebook Subsystem Power |
|---|---|
|
Use Scenario: Powering ultra-low-power ADCs, MEMS accelerometers, and Bluetooth LE radios in wearable health monitors. IC Role / Device Role / Timing Role: Primary 1.8-V supply rail regulator delivering clean, stable voltage to mixed-signal ICs with tight noise and accuracy requirements. Use Value: 0.7 µV/√Hz output noise and 2% accuracy ensure measurement fidelity; 1-µF ceramic compatibility shrinks BOM footprint. |
Use Scenario: Supplying 1.8-V I/O banks for DDR memory interfaces or PCIe controller auxiliary rails in thin-and-light notebooks. IC Role / Device Role / Timing Role: Local point-of-load regulator providing fast transient response and low dropout to maintain voltage under dynamic load changes. Use Value: 250 mV dropout at 500 mA allows operation from 2.05 V input - enabling efficient use of shared 3.3 V or boosted 2.5 V system rails. |
| Industrial PLC I/O Modules | Automotive Infotainment Core Logic |
|
Use Scenario: Regulating 1.8-V supply for isolated CAN transceivers and low-power microcontrollers in DIN-rail mounted controllers. IC Role / Device Role / Timing Role: Fixed-output LDO ensuring reliable startup and operation across –40°C to 125°C ambient with no enable control needed. Use Value: Guaranteed –40°C to 125°C operation and thermal shutdown protect against field failures in unventilated enclosures. |
Use Scenario: Providing 1.8-V core voltage to application processors or display interface ICs in head-unit infotainment systems. IC Role / Device Role / Timing Role: Secondary LDO supplying noise-sensitive logic blocks downstream of main DC/DC converter. Use Value: 55 dB ripple rejection at 120 Hz attenuates switching artifacts from upstream buck converters, preventing digital glitches. |
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 |
|---|---|---|---|
| TPL7407LDR | 7-channel 100-mA sink driver with integrated LDO; not a standalone 500-mA regulator - lacks SNS pin and 1.8-V fixed option. | Targeted at LED/relay driving with local bias; unsuitable as primary 1.8-V power rail for digital ICs. | Select only if driving discrete loads is primary function and 1.8-V regulation is secondary. |
| TLV70718PDQNR | 500-mA, 1.8-V LDO in 4-pin X2SON; 250 mV dropout, 25 µA IQ, but no SNS pin and only 1% accuracy over 0°C–70°C. | Lacks remote sensing and extended temperature grade; suitable for commercial-grade consumer devices only. | Prefer for cost-sensitive, non-automotive applications where SNS and –40°C operation are unnecessary. |
Compared with TPL7407LDR and TLV70718PDQNR, the LP38691SD-1.8/NOPB uniquely combines 500-mA capability, SNS-enabled remote sensing, –40°C to 125°C guaranteed operation, and WSON thermal performance - making it the only choice for ruggedized 1.8-V point-of-load regulation where accuracy, noise, and thermal reliability are co-critical.
Availability
LP38691SD-1.8/NOPB is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and battery-powered medical devices requiring stable component supply, long-term manufacturability, and automotive-grade thermal resilience.
Supply support for LP38691SD-1.8/NOPB 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 specializing in analog and embedded processing technologies, with leadership in power management ICs for industrial, automotive, and portable applications.
The LP3869x family was designed specifically for battery-powered digital systems demanding accurate, low-noise, low-dropout regulation with minimal external components - targeting space-constrained, thermally challenging environments.
FAQ
What is the minimum input voltage required for LP38691SD-1.8/NOPB to regulate 1.8 V at 500 mA?
The LP38691SD-1.8/NOPB requires a minimum input voltage of approximately 2.05 V at 500 mA load, based on its typical dropout voltage curve for 1.8-V output. This value increases slightly at higher temperatures or lower input voltages due to thermal derating - always verify using Figure 22 (Dropout vs IOUT) in the SNVS321O datasheet.
Does LP38691SD-1.8/NOPB have an enable pin?
No, the LP38691SD-1.8/NOPB does not include an enable (EN) pin. It is a permanently enabled regulator - power is delivered as soon as valid input voltage (≥2.7 V) is applied. For enable functionality, consider the pin-compatible LP38693SD-1.8/NOPB variant, which adds EN control while sharing identical output specs and package.
Can LP38691SD-1.8/NOPB be used with a 0.47-µF ceramic output capacitor?
No - the LP38691SD-1.8/NOPB requires a minimum 1-µF ceramic output capacitor for guaranteed stability, as specified in the datasheet's Typical Application Circuits and Section 9.2.2.3. Using 0.47 µF may cause oscillation or poor transient response; TI does not characterize or guarantee performance below 1 µF.
What is the purpose of the SNS pin on LP38691SD-1.8/NOPB?
The SNS (sense) pin on LP38691SD-1.8/NOPB enables remote voltage sensing at the load to compensate for IR drop in PCB traces. It must be connected directly to the regulated output node (OUT) - not to the LDO's output pin - to close the feedback loop at the point of load, improving regulation accuracy under varying current conditions.
Is LP38691SD-1.8/NOPB qualified for automotive applications?
No - LP38691SD-1.8/NOPB is the commercial-grade version. For automotive use, select LP38691QSD-1.8/NOPB (AEC-Q100 Grade 1, –40°C to 125°C), which shares identical electrical specs and pinout but includes automotive qualification testing, enhanced ESD robustness, and controlled manufacturing flow.
LP38691SD-1.8/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 6-WDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 1.8V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- 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)
LP38691SD-1.8/NOPB FAQ
1.How can I place an order for LP38691SD-1.8/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LP38691SD-1.8/NOPB 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 LP38691SD-1.8/NOPB reliable?
The price and inventory of LP38691SD-1.8/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP38691SD-1.8/NOPB is usually 5 days.
3.What payment methods are accepted for LP38691SD-1.8/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP38691SD-1.8/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP38691SD-1.8/NOPB?
LP38691SD-1.8/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP38691SD-1.8/NOPB 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 LP38691SD-1.8/NOPB?
For technical support, including LP38691SD-1.8/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP38691SD-1.8/NOPB requirements.
6.How does Aetrix verify that LP38691SD-1.8/NOPB is sourced from the original manufacturer or authorized distributors?
All LP38691SD-1.8/NOPB 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 LP38691SD-1.8/NOPB meets industry standards.
7.What is the process for return or replacement of LP38691SD-1.8/NOPB?
All LP38691SD-1.8/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LP38691SD-1.8/NOPB, 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 LP38691SD-1.8/NOPB part is unused and in its original packaging.
Return procedure for LP38691SD-1.8/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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