LM317DCYR - 1.5A Adjustable Positive Regulator | TI
MPN: LM317DCYR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.42 | $0.42 |
| 10 | $0.35 | $3.50 |
| 100 | $0.28 | $28.00 |
| 500 | $0.24 | $120.00 |
| 1,000 | $0.21 | $210.00 |
Drop-in alternatives for LM317DCYR β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
LM317DCY
β Drop-Inπ Reference alternative (not in catalog)
LM317MDCY
β Drop-Inπ Reference alternative (not in catalog)
LM317DCYR
β Drop-Inβ In Stock
$0.21 / Unit
View Datasheet βLM317DCYR Maximum Ratings & Electrical Characteristics
| Output Type | Adjustable |
| Output Voltage Range | 1.25 V to 37 V |
| Maximum Output Current | 1.5 A |
| Input Voltage Range | Up to 40 V |
| Dropout Voltage | 2.5 V typical at 1.5 A |
| Line Regulation | 0.01% typical |
| Load Regulation | 0.1% typical |
| Reference Voltage | 1.25 V |
| Quiescent Current | 3.5 mA typical |
| Operating Temperature Range | 0Β°C to +125Β°C |
| Package | SOT-223-4 |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Current Limiting | Internal |
| Thermal Overload Protection | Yes |
LM317DCYR Pin Configuration
| Pin 1 | ADJ β Adjustment pin for setting output voltage |
| Pin 2 | OUT β Regulated output voltage |
| Pin 3 | IN β Input supply voltage |
| Pin 4 | TAB β Thermal pad, connected to OUT |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
LM317DCYR is suitable for 6 applications: Adjustable Power Supply, Battery Charger, LED Driver, Audio Equipment Power Supply, Industrial Control Systems, Test and Measurement Equipment.
Adjustable Power Supply
The LM317DCYR is ideal for building adjustable bench power supplies. Its output voltage can be set from 1.25V to 37V using two external resistors, providing a versatile supply for prototyping and testing. The device's 1.5A output current and internal protection features ensure reliable operation. With typical line regulation of 0.01% and load regulation of 0.1%, it delivers stable output for sensitive circuits. The SOT-223-4 package allows compact PCB designs, and the low dropout voltage of 2.5V ensures efficient operation with moderate input-output differentials.
Recommended
Battery Charger
The LM317DCYR can be configured as a constant-current/constant-voltage charger for lead-acid or lithium batteries. By setting the output voltage to the battery's float voltage and using a resistor to limit current, it provides a simple and effective charging solution. The device's current limiting and thermal protection prevent overcharging and overheating. With a 1.5A output capability, it can charge medium-capacity batteries efficiently. The adjustable output allows precise voltage settings for different battery chemistries, making it a flexible choice for DIY and industrial chargers.
Recommended
LED Driver
The LM317DCYR is commonly used as a constant-current source for driving LEDs. By placing a resistor between the output and adjustment pins, the output current is set to 1.25V/R, providing a stable current for LED strings. This ensures uniform brightness and protects LEDs from current spikes. The device's thermal protection is beneficial in high-power LED applications. With a 1.5A output, it can drive multiple high-power LEDs in series. The SOT-223-4 package is suitable for compact lighting modules, and the adjustable current allows fine-tuning for different LED configurations.
Recommended
Audio Equipment Power Supply
The LM317DCYR is used in audio equipment to provide a clean, adjustable power supply for op-amps, DACs, and preamplifiers. Its low output noise and high PSRR (though not specified, linear regulators inherently have low noise) make it suitable for audio circuits. The adjustable output allows optimization of supply voltages for different audio stages. The device's thermal protection ensures reliable operation in enclosed audio equipment. With a 1.5A output, it can power multiple audio ICs. The SOT-223-4 package is compact, fitting into tight audio chassis designs.
Recommended
Industrial Control Systems
The LM317DCYR is widely used in industrial control systems for providing regulated supply voltages to microcontrollers, sensors, and actuators. Its wide input voltage range (up to 40V) allows it to operate from 24V industrial buses. The adjustable output enables generation of various voltage rails (e.g., 3.3V, 5V, 12V) from a single design. The device's robust protection features, including current limiting and thermal shutdown, ensure reliable operation in harsh environments. The SOT-223-4 package is suitable for PCB mounting in control panels, and the 1.5A output can power multiple loads.
Recommended
Test and Measurement Equipment
The LM317DCYR is used in test and measurement equipment to provide precise, adjustable reference voltages for calibration and signal conditioning. Its low line and load regulation (0.01% and 0.1%) ensure accurate voltage outputs. The adjustable feature allows fine-tuning of reference voltages for different measurement ranges. The device's thermal stability contributes to consistent performance over temperature. With a 1.5A output, it can supply power to multiple test circuits. The SOT-223-4 package is convenient for compact benchtop instruments, and the device's reliability is essential for long-term measurement accuracy.
Recommended
Recommended Products Summary
Engineering reference data for LM317DCYR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM317DCY | LM317MDCY | LM317DCYR (UMW) | LM317T | LM317MDT |
|---|---|---|---|---|---|---|
| Package | SOT-223-4 | SOT-223-4 | SOT-223-4 | SOT-223-4 | TO-220 | TO-252 |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | UMW | STMicroelectronics | Texas Instruments |
| Output Current | 1.5 A | 1.5 A | 1.5 A | 1.5 A | 1.5 A | 1.5 A |
| Output Voltage Range | 1.25V to 37V | 1.25V to 37V | 1.25V to 37V | 1.25V to 37V | 1.25V to 37V | 1.25V to 37V |
| Dropout Voltage | 2.5V typical | 2.5V typical | 2.5V typical | 2.5V typical | 2.5V typical | 2.5V typical |
| Line Regulation | 0.01% typical | 0.01% typical | 0.01% typical | 0.01% typical | 0.01% typical | 0.01% typical |
| Load Regulation | 0.1% typical | 0.1% typical | 0.1% typical | 0.1% typical | 0.1% typical | 0.1% typical |
| Input Voltage Max | 40V | 40V | 40V | 40V | 40V | 40V |
Key Differentiators
- SOT-223-4 package for compact designs (vs LM317T (TO-220))
- Tape and reel packaging for automated assembly (vs LM317DCY (tube))
- Wide availability and low cost (vs LM317MDCY)
Design Notes
The LM317DCYR in SOT-223-4 package has limited thermal dissipation capability. At high input-output voltage differentials and currents, the power dissipation (PD = (VIN - VOUT) * IOUT) can exceed the package's ability to dissipate heat. For example, at VIN=12V, VOUT=5V, and IOUT=1A, PD=7W, which is too high for SOT-223 without a heatsink. Use a larger copper area on the PCB or consider a TO-220 package for higher power applications.
Place input and output capacitors close to the LM317DCYR pins. A 0.1uF capacitor on the input and a 1uF tantalum or electrolytic capacitor on the output are recommended for stability. The adjustment pin should be bypassed with a 10uF capacitor to improve ripple rejection. Ensure the thermal pad (pin 4) is connected to a generous copper area for heat dissipation.
Do not exceed the maximum input voltage of 40V. Ensure the input-output voltage differential is at least 3V to maintain regulation. Use 1% or better resistors for the voltage divider to achieve accurate output voltage. If the output is shorted, the internal current limiting protects the device, but prolonged short circuits may cause thermal shutdown. Always include protection diodes if the output is connected to a load that can back-feed voltage.
Compliance Information
RoHS compliant per TI product page. Not AEC-Q100 qualified. Other compliance data not specified in provided sources.
