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Texas Instruments LP38691SDX-3.3/NOPB
- Part No.:
- LP38691SDX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 6-WDFN Exposed Pad
- Datasheet:
-
LP38691SDX-3.3/NOPB.pdf
- Description:
- IC REG LINEAR 3.3V 500MA 6WSON
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LP38691SDX-3.3/NOPB from Texas Instruments is a 500-mA, 3.3-V fixed-output low-dropout CMOS linear regulator in WSON-6 package, featuring 2% output accuracy (25°C), 250 mV dropout at 500 mA (VOUT = 5 V), 55 µA ground pin current at full load, and stable operation with only 1-µF ceramic output capacitor. It serves as a primary power rail for microcontroller cores and I/O in space-constrained portable instrumentation.
For engineers reviewing the LP38691SDX-3.3/NOPB datasheet, LP38691SDX-3.3/NOPB pinout, LP38691SDX-3.3/NOPB application, or LP38691SDX-3.3/NOPB equivalent, key selection criteria include dropout voltage at 3.3 V output, thermal performance in WSON-6, remote sense capability (SNS pin), quiescent current under light load, and compatibility with ceramic capacitors without ESR requirements.
Technical Context
The LP38691SDX-3.3/NOPB uses a PMOS pass transistor architecture, eliminating DC base-drive current and enabling ground pin current to remain below 100 µA across all load, input voltage, and temperature conditions. Its trimmed bandgap reference ensures 2% output accuracy over –40°C to 125°C, with line regulation of 0.03%/V and load regulation of 1.8%/A at 3.3 V output.
It integrates foldback current limiting (350 mA at VIN–VOUT > 5 V; 850 mA at VIN–VOUT < 4 V), thermal shutdown activation at 160°C with 10°C hysteresis, and operates stably with 1-µF input and output ceramic capacitors - no minimum ESR requirement. The SNS pin enables remote voltage sensing exclusively in WSON-package variants.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% (25°C), ±4% over –40°C to 125°C - ensures stable logic-level supply for 3.3-V microcontrollers and peripherals. |
| Max Output Current | 500 mA - supports moderate-power digital subsystems without external current boosting. |
| Dropout Voltage | 330 mV at 500 mA (VOUT = 3.3 V) - enables operation down to VIN = 3.63 V, critical for single-cell Li-ion or Li-poly battery systems. |
| Quiescent Current | 55 µA typical at full load - minimizes standby power loss in always-on sensor nodes and battery-backed modules. |
| Input Voltage Range | 2.7 V to 10 V - accommodates wide-input industrial supplies and multi-cell battery stacks. |
| PSRR | 55 dB at 120 Hz - suppresses ripple from switching pre-regulators or noisy DC/DC converters feeding the LDO. |
| Thermal Resistance θJA | 50.6°C/W (WSON-6) - allows 500-mA operation up to +85°C ambient with standard PCB copper area (2-in² 2-oz). |
Pinout & Package
The LP38691SDX-3.3/NOPB is housed in a 3.0 mm × 3.0 mm WSON-6 package with exposed thermal pad (DAP) on the bottom, requiring solder connection to PCB copper for thermal management. Pin 1 is IN, Pin 2 is GND, Pin 3 is OUT, Pin 4 is IN (dual-input configuration), Pin 5 is SNS (remote sense), and Pin 6 is NC (no internal connection). The DAP functions solely as a thermal path, not an electrical terminal.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pins 1, 4) | Input supply connection | Both pins must be tied together externally; each rated for ≤250 mA - enables robust current handling and reduced trace inductance in compact layouts. |
| GND (Pin 2) | Regulator ground reference | Low-impedance return path for control circuitry and load current; thermally coupled to die via package substrate. |
| OUT (Pin 3) | Regulated output voltage | Delivers stable 3.3 V to load; connects directly to SNS pin for local sensing or to remote load for precision regulation. |
| SNS (Pin 5) | Remote output voltage sense | Compensates for IR drop in PCB traces by closing feedback loop at load point - improves regulation accuracy to ±2% under dynamic load. |
| NC (Pin 6) | No internal connection | Must be left unconnected or grounded per layout best practice; no functional role in regulation or protection. |
| DAP (Exposed Pad) | Thermal interface | Requires solder mask-defined thermal pad (≥3×3 mm) connected to internal ground plane - reduces θJA by ~25% vs. non-thermal-pad packages. |
Key Features
| Feature | Design Value |
|---|---|
| Stable with 1-µF ceramic output capacitor | Eliminates need for tantalum or aluminum electrolytic capacitors - reduces board area, cost, and aging-related drift in portable designs. |
| PMOS pass transistor architecture | Maintains ground pin current ≤100 µA regardless of load, input voltage, or temperature - simplifies low-power system current budgeting. |
| Remote sensing (SNS pin) | Enables ±2% output accuracy at point-of-load under 500-mA dynamic load - critical for FPGA I/O banks and high-speed ADC references. |
| Foldback current limiting | Reduces short-circuit current to 350 mA when VIN–VOUT > 5 V - limits power dissipation during fault conditions without external current-limiting components. |
| Thermal shutdown with hysteresis | Activates at 160°C junction temperature and resets at 150°C - prevents thermal runaway while allowing safe recovery after transient overload. |
Applications
| Portable Medical Sensors | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Powering ultra-low-noise analog front-ends and BLE radio SoCs in handheld patient monitors with single-cell Li-ion battery input. IC Role / Device Role: Primary 3.3-V supply for signal chain and wireless transceiver, delivering clean, stable voltage despite battery voltage sag. Use Value: 0.7 µV/√Hz output noise and 55 dB PSRR ensure sub-16-bit ADC performance; 330-mV dropout extends usable battery life by ≥12% versus higher-dropout alternatives. |
Use Scenario: Regulating 3.3-V logic rails for isolated digital I/O channels in DIN-rail mounted programmable logic controllers operating in 0–70°C enclosures. IC Role / Device Role: Local post-regulator for field-side microcontrollers and level-shifters, rejecting ripple from 24-V DC-DC converters. Use Value: WSON-6 thermal resistance (50.6°C/W) enables full 500-mA output at 70°C ambient without heatsink; SNS pin maintains ±2% regulation across 15-cm backplane traces. |
| Automotive Body Control Units | Test & Measurement Handheld Meters |
|
Use Scenario: Supplying 3.3-V MCU cores and CAN transceivers in non-safety-critical body electronics (e.g., door modules, seat controls) with 8–16-V battery input. IC Role / Device Role: Secondary LDO after buck converter, providing low-noise, low-quiescent power for always-on wake-up circuitry. Use Value: 1-µA off-state quiescent current (LP38693 variant only; LP38691 draws 55 µA in shutdown) - not applicable here; LP38691SDX-3.3/NOPB maintains 55 µA ground current even at zero load, enabling predictable sleep-mode current modeling. |
Use Scenario: Powering precision op-amps, reference buffers, and display drivers in battery-operated multimeters and oscilloscope probes. IC Role / Device Role: Low-noise, low-drift voltage source for analog signal conditioning stages requiring <10 ppm/°C drift. Use Value: 2% initial accuracy and ±4% over –40°C to 125°C, combined with 0.03%/V line regulation, ensures measurement repeatability across temperature and input voltage variation. |
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 |
|---|---|---|---|
| TLS850F0TES/V33 | 500-mA automotive-grade LDO with integrated watchdog and reset generator; 350-mV dropout at 500 mA; requires 2.2-µF min. output capacitance. | Designed for ASIL-B safety compliance; includes diagnostic features absent in LP38691SDX-3.3/NOPB. | Select when functional safety monitoring (reset, window watchdog) is required alongside regulation - adds complexity but meets ISO 26262 requirements. |
| MCP1826T-3302E/DB | 500-mA LDO in SOT-223; 350-mV dropout at 500 mA; 2% accuracy; no SNS pin; 100-µA quiescent current. | Lacks remote sensing and has higher ground current - suitable where trace-length-induced voltage drop is negligible. | Choose for cost-sensitive industrial applications where PCB layout permits local regulation and thermal constraints allow SOT-223 footprint. |
Compared with TLS850F0TES/V33 and MCP1826T-3302E/DB, the LP38691SDX-3.3/NOPB uniquely combines WSON-6 thermal efficiency, SNS-based remote sensing, and 55-µA ground current - making it optimal for compact, high-accuracy analog/digital hybrid systems where layout space and point-of-load regulation are critical.
Availability
LP38691SDX-3.3/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, industrial PLC I/O modules, and test & measurement handheld meters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LP38691SDX-3.3/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, signal chain solutions, and high-reliability components for industrial, automotive, and consumer markets.
The LP38691SDX-3.3/NOPB belongs to TI's LP3869x family of low-dropout CMOS linear regulators, designed specifically for space-constrained, battery-powered digital systems requiring fast start-up, tight output tolerance, and ceramic-capacitor stability without ESR constraints.
FAQ
What is the dropout voltage specification for LP38691SDX-3.3/NOPB at full 500-mA load?
The LP38691SDX-3.3/NOPB has a typical dropout voltage of 330 mV at 500 mA load current when regulating 3.3 V output. This value is measured under standard conditions (TJ = 25°C, CIN = COUT = 10 µF) and increases slightly at –40°C and 125°C extremes. The dropout ensures reliable operation down to VIN = 3.63 V, supporting single-cell Li-ion batteries throughout their discharge curve.
Does LP38691SDX-3.3/NOPB support remote voltage sensing, and how is it implemented?
Yes, LP38691SDX-3.3/NOPB supports remote sensing via its dedicated SNS pin (Pin 5), which is exclusive to WSON-package variants. To implement remote sensing, connect the SNS pin directly to the load-side of the output trace - not to the regulator's OUT pin - thereby compensating for IR drop in PCB copper. This configuration maintains ±2% output accuracy at the load under full 500-mA dynamic current.
What is the thermal performance of LP38691SDX-3.3/NOPB in its WSON-6 package?
The LP38691SDX-3.3/NOPB in WSON-6 exhibits a junction-to-ambient thermal resistance (θJA) of 50.6°C/W under standard JEDEC High-K board conditions. With a maximum junction temperature of 125°C and 25°C ambient, this allows continuous 500-mA operation with up to 1.25 W power dissipation - achievable using a 3×3-mm DAP soldered to ≥2-in² of 2-oz internal copper ground plane.
Can LP38691SDX-3.3/NOPB operate stably with only 1-µF ceramic output capacitors?
Yes, LP38691SDX-3.3/NOPB is explicitly characterized and guaranteed stable with a single 1-µF ceramic output capacitor - no minimum ESR requirement. This eliminates dependency on bulkier tantalum or aluminum electrolytic capacitors, reducing board area and improving long-term reliability in portable and high-vibration environments.
How does the ground pin current behave across load and temperature for LP38691SDX-3.3/NOPB?
The LP38691SDX-3.3/NOPB maintains a ground pin current of 55 µA typical at full 500-mA load, and this value remains stable across input voltage (2.7–10 V), load current (0–500 mA), and temperature (–40°C to 125°C). This consistency stems from its PMOS pass transistor architecture, which avoids base-drive current - enabling precise system-level current budgeting in battery-powered designs.
LP38691SDX-3.3/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):
- 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/NOPB FAQ
1.How can I place an order for LP38691SDX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LP38691SDX-3.3/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 LP38691SDX-3.3/NOPB reliable?
The price and inventory of LP38691SDX-3.3/NOPB 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/NOPB is usually 5 days.
3.What payment methods are accepted for LP38691SDX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP38691SDX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP38691SDX-3.3/NOPB?
LP38691SDX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP38691SDX-3.3/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 LP38691SDX-3.3/NOPB?
For technical support, including LP38691SDX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP38691SDX-3.3/NOPB requirements.
6.How does Aetrix verify that LP38691SDX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LP38691SDX-3.3/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 LP38691SDX-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LP38691SDX-3.3/NOPB?
All LP38691SDX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LP38691SDX-3.3/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 LP38691SDX-3.3/NOPB part is unused and in its original packaging.
Return procedure for LP38691SDX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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