LM317DCYR - 1.5A Adjustable Positive Regulator | Texas Instruments
Référence : LM317DCYR ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $0.62 | $0,62 |
| 10 | $0.56 | $5,60 |
| 100 | $0.45 | $45,00 |
| 500 | $0.33 | $165,00 |
| 1 000 | $0.21 | $210,00 |
LM317DCYR Présentation
A linear regulator maintains a constant output voltage by dissipating excess power as heat. The LM317 is an adjustable linear regulator whose output is programmed by a resistor divider, with a fixed 1.25V reference between the output and adjustment pins. Linear regulators belong to the broader power management IC family, alongside switching regulators and LDOs, and are preferred in noise-sensitive circuits for their low output noise and fast transient response.
Key features include typical line regulation of 0.01% and load regulation of 0.1%, plus internal short-circuit current limiting, thermal overload protection, and safe-area compensation. The device supports input voltages up to 40V, with a typical dropout voltage of about 2.5V at 1.5A load. The junction temperature range of 0C to 125C covers commercial and industrial requirements.
Architecturally, the LM317 uses a bandgap reference and error amplifier. The 1.25V reference across the programming resistor makes the device double as a precise constant-current source, useful for LED driving and battery charging. The SOT-223-4 package offers good thermal performance with a reasonable PCB copper area, and the tab is connected to the output pin for direct heatsinking to a copper pour.
Typical applications include adjustable bench power supplies, battery chargers, LED constant-current drivers, audio equipment, instrumentation, and industrial control systems where a stable adjustable rail is required.
Design tip: maintain at least a 3V input-output differential for regulation, size copper pour for thermal dissipation, and bypass the adjustment pin with a capacitor to improve ripple rejection.
Alternatives de remplacement direct pour LM317DCYR — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec LM317DCYR (même facteur de forme et même empreinte) — différant par Maximum Output Current, Output Type, Protection Features, Reference Voltage.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
LM317QDCYRQ1
✅ Remplacement direct✓ En stock
$0.31 / unité
Voir la fiche technique →LM317MDT
⚡ Même boîtier ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
LM317D2TR4G
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
LM317S-13
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
LM317DCY
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
LM317DCYR Valeurs maximales et caractéristiques électriques
| Type de sortie | Adjustable positive |
| Plage de tension de sortie | 1.25 V to 37 V |
| Courant de sortie maximal | > 1.5 A |
| Maximum Input Voltage | 40 V |
| Line Regulation | 0.01% (typical) |
| Load Regulation | 0.1% (typical) |
| Tension de référence | 1.25 V (VOUT to ADJ) |
| Tension de déchet | Approximately 2.5 V at 1.5 A load |
| Protection Features | Current limiting, thermal overload, safe-area compensation |
| Température de jonction en fonctionnement | 0C to +125C |
| Boîtier | SOT-223-4 (DCY) |
| Type de montage | Surface Mount |
| Number of Terminals | 4 (3-terminal regulator + tab) |
| External Components | 2 resistors set output voltage |
| Statut RoHS | Compliant |
Configuration des broches de LM317DCYR
| Broche 1 | ADJ — Adjustment pin - 1.25V reference between this pin and output; connect resistor divider here |
| Broche 2 | OUT — Regulated output voltage (also connected to tab for heatsinking) |
| Broche 3 | VIN — Input supply voltage, up to 40V |
| Broche 4 | TAB — Mechanical tab connected to OUT for thermal dissipation to copper pour or heatsink |
Applications typiques
LM317DCYR convient pour 6 applications: Adjustable Bench Power Supplies, Battery Chargers, LED Constant-Current Drivers, Audio Equipment Power Rails, Industrial Control and Instrumentation, Post-Regulation After Switching Converters.
Adjustable Bench Power Supplies
The LM317DCYR is the classic core of DIY and lab adjustable bench supplies. Its 1.25V to 37V output range with a simple two-resistor programming network lets designers dial in any rail without firmware or external controllers. With 1.5A capability, 0.01% line regulation and 0.1% load regulation, output remains stable across line and load steps, while internal current limiting and thermal shutdown provide fault tolerance. A potentiometer in place of R2 gives continuous adjustment; the tab can be soldered to a copper area or heatsink for higher dissipation.
Recommandé
Battery Chargers
Per the TI datasheet typical applications, the LM317DCYR serves as a simple lead-acid or NiCd charger by programming a current-limited, voltage-regulated output with two resistors plus a series resistor for current limiting. The 1.25V reference between OUT and ADJ makes constant-current charging trivial: charging current equals 1.25V divided by the sense resistor. Input voltage up to 40V supports charging from automotive or unregulated adapter rails, while built-in thermal overload and safe-area compensation protect against fault conditions during long charge cycles.
Recommandé
LED Constant-Current Drivers
The LM317DCYR doubles as a linear constant-current LED driver because the fixed 1.25V across the ADJ-to-OUT resistor defines LED current: I = 1.25V / R. An 8.3 ohm resistor yields 150mA; a 1.25 ohm resistor yields 1A. This topology needs no inductors or controller ICs, costs pennies, and inherits the LM317's thermal shutdown and current limiting as intrinsic protection. Trade-off: efficiency is limited to roughly VLED/VIN, so it suits low- and medium-power indicator and accent lighting rather than high-efficiency luminaires.
Recommandé
Audio Equipment Power Rails
Linear regulation eliminates switching noise, and the LM317DCYR provides quiet analog rails for preamps, headphone amplifiers, and op-amp stages. Unlike buck converters, it injects no switching ripple, and adding a 10uF bypass capacitor on the ADJ pin raises ripple rejection further per the TI datasheet. With 0.01% line regulation, supply-induced hum and noise stay minimal. Place it downstream of a rectifier or preregulator with at least 3V headroom, and budget copper area for the (VIN - VOUT) x ILOAD dissipation at high listening currents.
Recommandé
Industrial Control and Instrumentation
In factory controllers, sensor front ends, and instrumentation, the LM317DCYR generates well-regulated intermediate or analog rails from 24V-class industrial supplies, thanks to its 40V input rating. Internal short-circuit current limiting, thermal overload protection, and safe-area compensation give robust behavior under fault and brownout conditions common in industrial environments. The surface-mount SOT-223-4 package withstands reflow assembly for automated production, and its two-resistor programming lets one PCB design support multiple rail voltages by changing a single resistor value.
Recommandé
Post-Regulation After Switching Converters
A common architecture pairs the LM317DCYR after a buck converter to strip switching ripple and tighten load regulation for sensitive analog loads. The buck handles the high-efficiency bulk step-down; the LM317 provides a clean final rail with 0.1% load regulation. Because the preregulator holds VIN-VOUT small, the linear stage dissipates little power, combining switching efficiency with linear-rail cleanliness. Keep at least 3V of headroom for LM317 regulation, and use 10uF input and output ceramics with an ADJ bypass capacitor for best transient and ripple performance.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour LM317DCYR — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | LM317QDCYRQ1 | LM317D2TR4G | LM317S-13 |
|---|---|---|---|---|
| Package | SOT-223-4 (DCY) | SOT-223-4 (DCY) - same | SOT-223 - same footprint | SOT-223 - same footprint |
| Brand | Texas Instruments | Texas Instruments | onsemi | Diodes Incorporated |
| Output Voltage Range | 1.25 V to 37 V | 1.25 V to 37 V | 1.25 V to 37 V | 1.25 V to 37 V |
| Output Current | > 1.5 A | > 1.5 A | > 1.5 A | > 1.5 A |
| Automotive Grade (AEC-Q100) | No | Yes (Q1) | No | No |
Principaux différenciateurs
- Automotive-qualified variant available on same footprint (vs LM317QDCYRQ1)
- Wide 40V input and 37V output range (vs LM317S-13)
- Only two external resistors for full adjustability (vs Fixed-output LDOs (e.g., TPS7133QDR))
Notes de conception
Power dissipation is (VIN - VOUT) x ILOAD. At 12V in, 5V out, 1A load, the LM317DCYR dissipates 7W, far beyond what a bare SOT-223 can handle. Connect the output tab to a generous copper pour (1 square inch or more) or an external heatsink, and verify junction temperature stays below 125C. Keep at least 3V input-output differential for guaranteed regulation per the TI datasheet.
Place the programming resistors close to the ADJ pin to keep the sense path short and noise-free. Use 0.1uF ceramic input bypass if the regulator is more than a few inches from the input filter capacitor, and 1uF or 10uF tantalum/ceramic on the output for transient response. The tab (OUT) copper area serves double duty as electrical connection and heatsink.
Do not omit the output capacitor if the ADJ pin is bypassed - an output capacitor without proper diode protection can discharge into the regulator on input short, damaging it. Add a protection diode from OUT to IN if input shorts are possible and output capacitance exceeds about 10uF. Ensure the ADJ pin leakage path resistor (R1, typically 240 ohm) is always present or the output floats high.
Informations de conformité
RoHS compliant per TI product page. AEC-Q100 qualification applies to the LM317QDCYRQ1 variant, not the standard LM317DCYR. REACH and halogen-free status not stated in provided data.
