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Texas Instruments LP38690SDX-ADJ
- Part No.:
- LP38690SDX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 6-WDFN Exposed Pad
- Datasheet:
-
LP38690SDX-ADJ.pdf
- Description:
- IC REG LINEAR POS ADJ 1A 6WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,014
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Product details
Overview
LP38690SDX-ADJ from Texas Instruments is a 1-A adjustable-output low-dropout CMOS linear regulator with PMOS pass transistor, stable with 1-µF ceramic output capacitors, 450-mV dropout at 1 A (5-V output), and ±2.5% ADJ pin voltage accuracy at 25°C - used in battery-powered portable instrumentation requiring precise, low-noise DC power.
For engineers reviewing the LP38690SDX-ADJ datasheet, LP38690SDX-ADJ pinout, LP38690SDX-ADJ application, or LP38690SDX-ADJ equivalent, key selection factors include dropout voltage vs. load current, ground pin current stability across temperature, thermal resistance of WSON package, and compatibility with ultralow-ESR ceramic capacitors without external compensation.
Technical Context
The LP38690SDX-ADJ employs a precision trimmed 1.25-V bandgap reference and PMOS pass element to achieve ultra-low ground current (55 µA typical at full load) independent of input voltage, load, or temperature. Its foldback current limiting activates at VIN–VOUT > 5 V (450 mA limit) and relaxes to 1500 mA when differential drops below 4 V.
No enable pin is present - unlike the LP38692-ADJ variant - making it a fixed-function, always-on LDO optimized for simplicity and minimal quiescent current. It operates across –40°C to +125°C with guaranteed specs and integrates thermal shutdown (160°C activation, 10°C hysteresis).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 1 A maximum continuous - supports high-current digital loads like HDD logic rails or FPGA I/O banks. |
| Dropout Voltage | 450 mV typical at 1 A, 5-V output - enables regulation from 5.45-V input down to 5-V rail with margin. |
| ADJ Pin Voltage | 1.25 V ±2.5% at 25°C - sets output via R1/R2 divider; enables 1.25–9-V adjustable range with <±0.5% line/load regulation error. |
| Ground Pin Current | 55 µA typical at full load - remains stable across temperature and input voltage, minimizing system standby power loss. |
| Input Voltage Range | 2.7 V to 10 V - compatible with single-cell Li-ion (3.0–4.2 V), dual-cell alkaline (3.0–3.6 V), or 5/9-V wall adapters. |
| Thermal Resistance θJA | 50.6°C/W (WSON-6 NGG) - allows full 1-A operation up to +85°C ambient with standard 4-via thermal pad layout. |
| PSRR | 55 dB at 120 Hz - suppresses ripple from upstream switching converters feeding the LDO input. |
Pinout & Package
LP38690SDX-ADJ is packaged in a 6-pin WSON (NGG) with 3.00 mm × 3.00 mm body and exposed thermal pad (DAP) on bottom for PCB heat sinking. Pins 1 and 6 are both IN terminals and must be tied together for full 1-A operation (250 mA max per pin).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pins 1, 6) | Input supply connection | Two parallel input pins reduce trace resistance and thermal stress; both must be connected to same input net. |
| GND (Pin 2) | Regulator circuit ground | Reference node for feedback and internal bias; connects to PCB ground plane under DAP for thermal conduction. |
| NC (Pin 3) | No internal connection | Unbonded die pad - must be left floating or connected to GND only if required by PCB layout rules (no electrical function). |
| ADJ (Pin 4) | Feedback reference node | Senses 1.25-V reference; connects to R1–R2 divider junction to set VOUT = 1.25 × (1 + R1/R2). |
| OUT (Pin 5) | Regulated output terminal | Delivers stabilized voltage; requires local 1-µF ceramic capacitor directly between OUT and GND for stability. |
| DAP (Bottom) | Thermal interface | Exposed copper pad soldered to PCB thermal plane - mandatory for achieving rated 1-A current and θJA = 50.6°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Stable with 1-µF ceramic output cap | Eliminates need for tantalum or electrolytic capacitors - reduces board area, cost, and aging-related failure modes. |
| PMOS pass transistor | Enables ground pin current ≤100 µA regardless of load, input, or temperature - critical for battery runtime in always-on systems. |
| Foldback current limiting | Protects device during short-circuit or overcurrent: limits to ~450 mA at high VIN–VOUT, scaling to 1500 mA as differential decreases. |
| Guaranteed –40°C to +125°C operation | All electrical specs validated across full industrial/junction temperature range - suitable for automotive under-hood or industrial control environments. |
| Low-noise output | 0.7 µV/√Hz (10 Hz–10 kHz) - preserves signal integrity in ADC reference, sensor front-end, or RF bias applications. |
Applications
| Hard Disk Drive Power Rail | Notebook System Core Logic |
|---|---|
Use Scenario: Supplies regulated 3.3-V or 2.5-V power to HDD controller ASIC and servo motor driver ICs from noisy 5-V or 12-V intermediate bus. IC Role / Device Role / Timing Role: Low-noise, high-PSRR LDO delivering clean, stable voltage to noise-sensitive analog and mixed-signal blocks. Use Value: Prevents data corruption and servo jitter by rejecting switching ripple from upstream DC/DC converters and maintaining tight load regulation (<5%/A) under dynamic head-positioning currents. | Use Scenario: Powers DDR memory termination (VTT) or chipset I/O rails in ultraportable notebooks using single-cell Li-ion battery (3.0–4.2 V). IC Role / Device Role / Timing Role: Adjustable LDO enabling flexible rail generation from limited input voltage range while minimizing dropout-induced brownouts. Use Value: Delivers full 1-A output even at battery end-of-discharge (3.0 V), thanks to 450-mV dropout and 1.25-V reference accuracy - extends usable runtime by >12% versus higher-dropout alternatives. |
| Battery-Powered Portable Instrumentation | Industrial Sensor Signal Conditioning |
Use Scenario: Provides precision 1.8-V or 2.8-V supply to microcontroller, ADC, and op-amp stages in handheld multimeters or gas analyzers. IC Role / Device Role / Timing Role: Primary analog power source ensuring low-noise, thermally stable voltage for high-resolution measurement circuits. Use Value: 0.7 µV/√Hz noise and ±2.5% ADJ accuracy maintain <16-bit effective resolution; 55-µA ground current extends 200-mAh coin-cell life to >1000 hours in sleep mode. | Use Scenario: Powers isolated 4–20-mA transmitter ICs and precision instrumentation amplifiers in factory-floor pressure/temperature transmitters. IC Role / Device Role / Timing Role: Robust, wide-input LDO handling 9–36-V loop-powered inputs while delivering stable 5-V or 3.3-V analog supply. Use Value: Operates reliably from 2.7–10-V input with guaranteed specs to +125°C - eliminates need for external pre-regulation and supports extended temperature qualification per IEC 61000-6-2. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable-output LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LP38692SDX-ADJ | Includes EN pin; same WSON-6 package, 1.25-V reference, and 1-A rating; 6-pin pinout differs (EN replaces NC). | Required where system-level power sequencing or standby mode control is needed - not drop-in compatible due to pin function change. | Select LP38692SDX-ADJ only if enable functionality is essential; otherwise LP38690SDX-ADJ offers simpler layout and lower BOM count. |
| TLS850B0TBV50 | Automotive-qualified 500-mA LDO with integrated watchdog and reset; 5-V fixed output; SOIC-8 package; higher dropout (600 mV @ 500 mA). | Targeted at ASIL-B automotive ECUs - includes safety features absent in LP38690SDX-ADJ; not adjustable and lower current. | Choose TLS850B0TBV50 only for automotive functional safety compliance; LP38690SDX-ADJ remains preferred for cost-sensitive industrial/portable designs needing adjustability and 1-A output. |
Compared with LP38692SDX-ADJ, LP38690SDX-ADJ removes enable complexity for always-on use cases, while versus TLS850B0TBV50 it provides higher current, adjustable output, and non-automotive qualification - making it optimal for portable instrumentation and embedded computing where flexibility and efficiency dominate.
Availability
LP38690SDX-ADJ is available at Aetrix Electronics and suitable for hard disk drive power rails, notebook system core logic, and battery-powered portable instrumentation requiring stable component supply, long-lifecycle availability, and consistent parametric performance across production batches.
Supply support for LP38690SDX-ADJ 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 consumer markets.
The LP38690SDX-ADJ belongs to TI's low-dropout linear regulator product line, engineered specifically for portable, battery-powered digital systems demanding fast start-up, ceramic-capacitor stability, and ultra-low ground current across wide temperature ranges.
FAQ
What is the minimum output capacitor required for stable operation of the LP38690SDX-ADJ?
The LP38690SDX-ADJ requires a minimum 1-µF ceramic output capacitor placed within 1 cm of the OUT and GND pins. It is stable with ESR values from 0 mΩ to 100 mΩ, and X7R/X5R dielectrics are recommended to maintain capacitance across voltage and temperature. The LP38690SDX-ADJ does not require additional series resistance or compensation networks when using ceramic capacitors.
Does the LP38690SDX-ADJ have an enable (EN) pin?
No, the LP38690SDX-ADJ does not include an enable pin. That functionality is exclusive to the LP38692-ADJ variant. The LP38690SDX-ADJ operates continuously when input voltage is applied - it has no shutdown mode or logic-controlled turn-off capability. If system-level power control is needed, external MOSFET switching on the input rail must be implemented.
What is the thermal performance of the LP38690SDX-ADJ in its WSON package?
The LP38690SDX-ADJ in the 6-pin WSON (NGG) package has a junction-to-ambient thermal resistance (θJA) of 50.6°C/W when mounted with four thermal vias under the exposed pad per JEDEC JESD51-5. This allows full 1-A operation up to +85°C ambient temperature with proper PCB copper area, and junction temperature remains within 125°C limit under typical load conditions.
How is the output voltage set on the LP38690SDX-ADJ?
The output voltage of the LP38690SDX-ADJ is set externally using two resistors (R1 and R2) connected in a divider network between OUT, ADJ, and GND. The formula is VOUT = 1.25 V × (1 + R1/R2). TI recommends R2 ≤12 kΩ to ensure ≥100 µA minimum load current and R2 ≤100 kΩ to avoid noise susceptibility at the ADJ node. The LP38690SDX-ADJ's 2.5% ADJ voltage accuracy directly determines output tolerance.
Is the LP38690SDX-ADJ compatible with reverse voltage conditions at the output?
The LP38690SDX-ADJ contains a parasitic body diode in its PMOS pass transistor that conducts reverse current if VOUT exceeds VIN by >500 mV. While brief reverse discharge (e.g., from output capacitor decay) is tolerated, continuous reverse current must be limited to <1 A. For systems prone to sustained reverse bias - such as dual-supply configurations - an external Schottky diode clamping OUT to GND is recommended to protect the LP38690SDX-ADJ.
LP38690SDX-ADJ 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:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 9V
- Voltage Dropout (Max):
- 1.6V @ 1A
- Current - Output:
- 1A
- 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:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 6-WSON (3x3)
LP38690SDX-ADJ FAQ
1.How can I place an order for LP38690SDX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LP38690SDX-ADJ 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 LP38690SDX-ADJ reliable?
The price and inventory of LP38690SDX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP38690SDX-ADJ is usually 5 days.
3.What payment methods are accepted for LP38690SDX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP38690SDX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP38690SDX-ADJ?
LP38690SDX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP38690SDX-ADJ 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 LP38690SDX-ADJ?
For technical support, including LP38690SDX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP38690SDX-ADJ requirements.
6.How does Aetrix verify that LP38690SDX-ADJ is sourced from the original manufacturer or authorized distributors?
All LP38690SDX-ADJ 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 LP38690SDX-ADJ meets industry standards.
7.What is the process for return or replacement of LP38690SDX-ADJ?
All LP38690SDX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LP38690SDX-ADJ, 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 LP38690SDX-ADJ part is unused and in its original packaging.
Return procedure for LP38690SDX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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