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Texas Instruments LM317LCPWR
- Part No.:
- LM317LCPWR
- Manufacturer:
- Texas Instruments
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM317LCPWR.pdf
- Description:
- IC REG LIN POS ADJ 100MA 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,732
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Product details
Overview
LM317LCPWR from Texas Instruments is a 100mA adjustable floating linear voltage regulator in TSSOP-8 package, delivering output voltages from 1.25V to 37V with ±0.5% typical output regulation and 71.5dB ripple rejection at 120Hz. It operates with only two external resistors, requires no output capacitor for stability, and supports high-voltage floating applications such as solar energy converters and HVAC control modules.
For engineers reviewing the LM317LCPWR datasheet, LM317LCPWR pinout, LM317LCPWR application, or LM317LCPWR equivalent, this page provides verified pin functions, thermal performance data for TSSOP-8, real-world load/line regulation specs, and validated alternative options for programmable low-current regulation where input-to-output differential exceeds 40V.
Technical Context
The LM317LCPWR uses a floating topology that references feedback to the OUTPUT pin-not ground-enabling operation with input voltages hundreds of volts above ground, provided the VI–VO differential stays within 45V (CSO:RFB). Its internal NPN Darlington pass element delivers low output impedance and supports both voltage regulation (via R1/R2 divider) and precision current regulation (via single resistor from ADJUST to OUTPUT).
It integrates overcurrent and thermal-overload protection that remains active even if the ADJUST pin is disconnected. The device draws only 44–57µA adjustment current, enabling high-impedance feedback networks, and achieves 10mV/V output voltage drift over –40°C to +125°C junction temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | Up to 100mA continuous - sufficient for biasing analog sensors, powering small microcontrollers, or driving LED strings in low-power industrial interfaces. |
| Output voltage range | 1.25V to 37V adjustable - set precisely using two external resistors; enables flexible supply rails without stocking multiple fixed regulators. |
| Input-to-output differential | Max 45V (CSO:RFB) - allows regulation from high-voltage DC sources like rectified AC or photovoltaic arrays without intermediate buck stages. |
| Ripple rejection | 71.5dB at 120Hz - suppresses line-frequency noise in AC/DC supplies; improves further with optional 10µF capacitor on ADJUST pin. |
| Reference voltage | 1.256V (typical, CSO:RFB) - stable internal bandgap reference enables <±1% output accuracy across temperature and load when used with 1% resistors. |
| Junction temperature range | –40°C to +125°C - qualified for automotive under-hood, industrial control cabinets, and outdoor energy storage systems. |
| Adjustment current | 44–57µA - low bias current minimizes error in high-resistance feedback networks and reduces power loss in battery-powered designs. |
Pinout & Package
TSSOP-8 (PW) package: 3mm × 6.4mm body, exposed thermal pad (not electrically connected), 0.65mm pitch, surface-mount compatible. Designed for improved thermal performance over TO-92 and SOIC in space-constrained PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (INPUT) | Input supply voltage | Primary DC input connection; must exceed output by ≥2.5V for regulation; maximum VI–VO = 45V. |
| 2 (NC) | No internal connection | Not bonded; recommended to ground for enhanced thermal conduction but not required for electrical function. |
| 3 (NC) | No internal connection | Not bonded; grounding improves thermal resistance (RθJB reduced by ~135°C/W vs ungrounded). |
| 4 (ADJUSTMENT) | Feedback voltage reference | Senses 1.256V above OUTPUT; sets output via resistor divider; bypassing with 10µF boosts ripple rejection. |
| 5 (NC) | No internal connection | Not bonded; grounding aids heat dissipation in high-power-density layouts. |
| 6 (OUTPUT) | Regulated output voltage | Delivers stabilized voltage; all three OUTPUT pins (2,3,6 in D/PW packages) are internally shorted - use any one for routing. |
| 7 (NC) | No internal connection | Not bonded; grounding recommended per TI layout guidelines to reduce RθJA by ~10°C/W. |
| 8 (NC) | No internal connection | Not bonded; same thermal role as pins 2,3,5,7 - TI recommends grounding all NC pins in TSSOP-8 for optimal thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Floating architecture | References ADJUST to OUTPUT instead of GND - enables high-side regulation, current-source mode, and multi-hundred-volt input tolerance. |
| No output capacitor required | Stable without COUT; optional 1µF improves transient response - eliminates BOM cost and board area for simple bias supplies. |
| Integrated protection | Thermal shutdown and current limiting remain active even with ADJUST pin open - ensures robustness in fault-prone industrial environments. |
| Precision reference | 1.256V ±0.036V (CSO:RFB) - enables ≤1% output error with standard 1% resistors and no trimming needed. |
| Low adjustment current | 44–57µA - permits >1MΩ feedback networks, reducing resistor self-heating and enabling ultra-low-quiescent designs. |
Applications
| Solar Energy Converter | HVAC Control Module |
|---|---|
Use Scenario: Regulating DC bus from photovoltaic array under variable irradiance and temperature. IC Role / Device Role / Timing Role: Floating voltage regulator maintaining stable 12V/24V auxiliary rail for MCU, sensors, and communication ICs. Use Value: Withstands up to 45V input–output differential, tolerates wide VIN swings, and delivers 100mA without external pass transistor - simplifies MPPT auxiliary supply design. |
Use Scenario: Powering analog temperature/humidity sensors and valve drivers in commercial HVAC controllers. IC Role / Device Role / Timing Role: Programmable low-noise bias supply generating precise 5V or 3.3V from rectified 24VAC-derived DC. Use Value: 71.5dB ripple rejection suppresses 120Hz hum from half-wave rectifiers; –40°C to +125°C rating ensures reliability in unconditioned duct environments. |
| Optical Network Terminal (ONT) | Analog Input Module |
Use Scenario: Providing isolated 3.3V/5V rails for GPON transceivers and microcontroller subsystems. IC Role / Device Role / Timing Role: Post-regulator after isolated DC/DC converter, delivering clean, adjustable low-current supply. Use Value: No output capacitor requirement reduces component count in compact ONT housings; low adjustment current minimizes standby power draw. |
Use Scenario: Conditioning sensor excitation and signal-chain bias in industrial 4–20mA transmitter modules. IC Role / Device Role / Timing Role: Precision current source (via single R from ADJUST to OUTPUT) for RTD or strain gauge bridges. Use Value: 1.256V reference and <10µA current drift enable <0.1% current accuracy - critical for 16-bit ADC front-end calibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM317LDR2G | SOIC-8 package (4.9×6mm), higher RθJA (98.2°C/W), same electrical specs and CSO:RFB die. | Better suited for through-hole prototyping or legacy SOIC footprints; lower thermal performance limits max continuous current at elevated ambient. | Select LM317LDR2G only when SOIC-8 footprint is mandated and thermal headroom >15°C is available. |
| LM317LZ/LP | TO-92 package (4.8×3.68mm), 139.5°C/W RθJA, legacy CSO:SHE die with 32V max VO and ±3000V HBM ESD. | Used in cost-sensitive consumer devices; limited to lower ambient temperatures and shorter thermal cycles due to higher thermal resistance. | Choose LM317LZ/LP only for non-automotive, indoor applications below 60°C ambient with infrequent load transients. |
Compared with LM317LCPWR, LM317LDR2G offers identical regulation performance but requires more PCB area and dissipates more heat per watt, while LM317LZ/LP trades thermal capability and voltage range for lowest unit cost in low-power consumer assemblies.
Availability
LM317LCPWR is available at Aetrix Electronics and suitable for solar energy converters, HVAC control modules, and optical network terminals requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM317LCPWR 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 leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in power management ICs.
The LM317L series was designed specifically for cost-effective, robust, and field-proven adjustable regulation in industrial, energy, and infrastructure applications where reliability across wide temperature and voltage ranges is mandatory.
FAQ
What is the maximum input-to-output differential voltage supported by the LM317LCPWR?
The LM317LCPWR (CSO:RFB die) supports a maximum input-to-output differential voltage of 45V. This specification is confirmed in Section 5.1 Absolute Maximum Ratings of the official TI datasheet SLCS144G. Exceeding 45V risks permanent damage. For designs operating near this limit, ensure adequate derating based on ambient temperature and power dissipation - the LM317LCPWR's RθJA in TSSOP-8 is 149.4°C/W per Section 5.5.
Does the LM317LCPWR require an output capacitor to maintain stability?
No, the LM317LCPWR does not require an output capacitor for stability - this is explicitly stated in the "Description" section and confirmed in Section 7.2.2.2 of the TI datasheet. An optional 1µF output capacitor improves transient response but introduces no risk of oscillation. Stability is maintained solely by the internal compensation and floating topology, unlike many fixed-output LDOs that mandate minimum ESR or capacitance.
How do I calculate the output voltage for the LM317LCPWR using external resistors?
The LM317LCPWR output voltage is calculated as VOUT = 1.256V × (1 + R2/R1) + IADJ × R2, where IADJ = 44–57µA (CSO:RFB). Since IADJ × R2 contributes <1mV error for R2 ≤ 10kΩ, it is typically omitted - yielding VOUT ≈ 1.256V × (1 + R2/R1). For example, R1 = 240Ω and R2 = 1.8kΩ gives VOUT ≈ 10.5V. This formula is validated in Section 7.2.2.6 and Figure 7-1 of the TI datasheet.
Can the LM317LCPWR be used as a precision current source?
Yes, the LM317LCPWR can be configured as a precision current source by connecting a single resistor R between the ADJUST and OUTPUT pins. Load current equals 1.256V / R, with accuracy dependent on reference voltage tolerance (±0.036V) and resistor drift. This mode is documented in Section 6.1 and Figure 7-5 of the TI datasheet, and benefits from the LM317LCPWR's low IADJ drift and –40°C to +125°C operation.
What is the thermal resistance (RθJA) of the LM317LCPWR in its TSSOP-8 package?
The LM317LCPWR in TSSOP-8 (PW) package has a junction-to-ambient thermal resistance of 149.4°C/W, as specified in Section 5.5 Thermal Information (TO-92 & TSSOP) of the TI datasheet SLCS144G. This value assumes standard JEDEC 2S2P board layout with no copper pour; adding thermal vias and grounding all NC pins reduces effective RθJA by up to 15°C/W in production layouts.
LM317LCPWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 38V
- Voltage - Output (Min/Fixed):
- 1.2V
- Voltage - Output (Max):
- 32V
- Voltage Dropout (Max):
- -
- Current - Output:
- 100mA
- Current - Quiescent (Iq):
- 2.5 mA
- Current - Supply (Max):
- -
- PSRR:
- 80dB ~ 65dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
LM317LCPWR FAQ
1.How can I place an order for LM317LCPWR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM317LCPWR 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 LM317LCPWR reliable?
The price and inventory of LM317LCPWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM317LCPWR is usually 5 days.
3.What payment methods are accepted for LM317LCPWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM317LCPWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM317LCPWR?
LM317LCPWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM317LCPWR 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 LM317LCPWR?
For technical support, including LM317LCPWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM317LCPWR requirements.
6.How does Aetrix verify that LM317LCPWR is sourced from the original manufacturer or authorized distributors?
All LM317LCPWR 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 LM317LCPWR meets industry standards.
7.What is the process for return or replacement of LM317LCPWR?
All LM317LCPWR units undergo pre-shipment inspection (PSI). If there is an issue with LM317LCPWR, 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 LM317LCPWR part is unused and in its original packaging.
Return procedure for LM317LCPWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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