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STMicroelectronics L78S09CV-DG
- Part No.:
- L78S09CV-DG
- Manufacturer:
- STMicroelectronics
- Package:
- TO-220-3
- Datasheet:
-
L78S09CV-DG.pdf
- Description:
- IC REG LINEAR 9V 2A TO220
- Quantity:
- Payment:
- Shipping:
Inventory:2,986
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Product details
Overview
L78S09CV-DG from STMicroelectronics is a three-terminal fixed-output positive voltage regulator IC delivering 9 V at up to 2 A, featuring internal current limiting, thermal shutdown, and safe operating area (SOA) protection. It operates with a minimum input voltage of 12 V (for ≤1 A load), exhibits 17 mΩ output resistance, and maintains ±5% output voltage accuracy over temperature and load - widely deployed in industrial power supplies and local on-card regulation for microcontroller subsystems.
For engineers reviewing the L78S09CV-DG datasheet, L78S09CV-DG pinout, L78S09CV-DG application, or L78S09CV-DG equivalent, key selection criteria include dropout behavior under 2 A load, thermal resistance (5 °C/W junction-to-case), short-circuit peak current (3 A), and ripple rejection (47 dB at 120 Hz) in linear-regulated power domains.
Technical Context
The L78S09CV-DG implements a monolithic series pass transistor architecture with embedded bandgap reference, error amplifier, and protection circuitry - enabling stable DC output without external compensation. Its SOA protection actively limits power dissipation during overload, while thermal shutdown activates at ~150 °C junction temperature.
Designed for fixed-voltage operation, it supports external configuration for adjustable outputs, constant-current regulation, or remote shutdown via the input pin. Input-to-output differential voltage must remain ≥3 V for full 2 A delivery, and output capacitance improves transient response but is not required for stability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 9.0 V ±5% (8.6–9.4 V at 1 A, 11 V input); enables direct replacement of legacy 9 V rail designs. |
| Max Output Current | 2 A continuous (with adequate heatsink); supports high-current analog or digital subsystems without parallel devices. |
| Input Voltage Range | 12 V min (for ≤1 A), 25 V max; requires ≥3 V headroom for full-load regulation. |
| Output Resistance | 17 mΩ at 1 kHz; ensures <17 mV load-induced droop per 1 A change - critical for precision analog rails. |
| Ripple Rejection | 47 dB at 120 Hz; suppresses AC line noise from unregulated DC inputs before rectification stages. |
| Quiescent Current | 8 mA typical; remains stable across input voltage (11–25 V) and load (20 mA–1 A), minimizing no-load loss. |
| Thermal Resistance | 5 °C/W junction-to-case; allows >2 A operation with TO-220 heatsink interface (e.g., 10 °C/W system RthJA yields ~75 °C rise at 2 A). |
Pinout & Package
Supplied in TO-220 (dual gauge) package with standard 3-pin vertical mounting footprint and metal tab electrically connected to Pin 2 (Ground). The case serves as thermal path and ground return.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Input) | Unregulated DC input supply | Accepts 12–25 V DC; must be decoupled near pin to limit high-frequency instability during transients. |
| Pin 2 (Ground) | Reference and return node | Common return for input, output, and internal protection circuits; metal tab is electrically tied to this pin. |
| Pin 3 (Output) | Regulated +9 V output | Delivers stable 9 V to load; output capacitor (optional) improves load-step response but not required for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Internal SOA Protection | Prevents destruction during sustained overload by dynamically limiting I×V product - eliminates need for external foldback circuitry. |
| Thermal Shutdown | Activates at ~150 °C junction temperature and auto-recovers after cooldown - ensures fault resilience in sealed enclosures. |
| Short-Circuit Peak Current | 3 A for transient events (e.g., hot-plug, capacitive inrush); sustains 500 mA continuous short-circuit current indefinitely. |
| Low Output Noise | 60 µV RMS (10 Hz–100 kHz); suitable for powering low-noise op-amps, ADC references, and sensor signal chains. |
| Fixed Output Architecture | No external resistors required; eliminates calibration drift and layout sensitivity inherent in adjustable regulators. |
Applications
| Industrial PLC Power Rails | Automotive Body Control Modules |
|---|---|
|
Use Scenario: Local 9 V supply for microcontroller I/O buffers, CAN transceivers, and relay drivers in programmable logic controllers. IC Role / Device Role / Timing Role: Primary linear regulator providing clean, protected 9 V rail independent of main 24 V bus fluctuations. Use Value: Eliminates single-point regulation distribution losses and withstands 2 A motor-driver surge loads without latch-up. |
Use Scenario: Powering window lift ECUs, seat position sensors, and interior lighting controllers in 12 V vehicle architectures. IC Role / Device Role / Timing Role: On-board 9 V regulator for mixed-signal ASICs requiring stable voltage despite battery voltage sag (down to 9 V) and load dump spikes. Use Value: Thermal shutdown and SOA protection prevent field failures during door-motor stall conditions or ESD events. |
| Test & Measurement Equipment | Point-of-Sale Terminal Power |
|
Use Scenario: Bias supply for precision op-amps and reference buffers in handheld multimeters and oscilloscope front-ends. IC Role / Device Role / Timing Role: Low-noise 9 V source replacing batteries or switching converters where ripple would corrupt µV-level measurements. Use Value: 60 µV RMS noise and 47 dB ripple rejection enable sub-0.01% measurement accuracy without post-regulation filtering. |
Use Scenario: Powering thermal print heads, EMV card readers, and display backlight drivers in retail POS terminals. IC Role / Device Role / Timing Role: Robust local regulator handling pulsed 2 A print-head current surges while maintaining 9 V for logic and communication ICs. Use Value: Internal current limiting and 3 A peak capability prevent brownouts during simultaneous print-and-communicate operations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7809CDT/NOPB | Higher quiescent current (6.5 mA vs. 8 mA), lower ripple rejection (42 dB), no SOA protection - relies on external current limiting. | Suitable only for low-surge, low-precision applications; cannot sustain 2 A continuously without derating. | Select when cost is primary constraint and thermal margin exceeds 25 °C; avoid in high-reliability or surge-prone systems. |
| LD1085V45 | Adjustable output (requires two resistors), higher dropout (1.3 V), lower max current (3 A), no integrated SOA - uses external sensing. | Enables flexible voltage scaling but adds BOM cost and layout complexity; lacks intrinsic short-circuit robustness. | Choose only if variable output or tighter dropout is mandatory; otherwise, L78S09CV-DG offers superior out-of-box reliability. |
Compared with LM7809CDT/NOPB and LD1085V45, the L78S09CV-DG delivers superior fault resilience through monolithic SOA and thermal protection, tighter output tolerance (±5% vs. ±2%), and lower output impedance - making it optimal for mission-critical 9 V rails where field failure risk must be minimized.
Availability
L78S09CV-DG is available at Aetrix Electronics and suitable for industrial PLC power rails, automotive body control modules, test & measurement equipment, and point-of-sale terminal power requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for L78S09CV-DG 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.
The L78S series belongs to ST's legacy linear regulator product line, engineered specifically for ruggedized fixed-voltage local regulation in harsh environments - emphasizing intrinsic protection, thermal robustness, and drop-in compatibility with classic 78xx designs.
FAQ
What is the minimum input voltage required for full 2 A output at 9 V?
The L78S09CV-DG requires a minimum input voltage of 12 V to deliver 2 A continuously, based on its 3 V dropout specification at full load. Below 12 V, output current capability degrades progressively; operation below 11 V is not guaranteed per datasheet electrical characteristics.
Does this regulator require an output capacitor for stability?
No - the L78S09CV-DG is internally compensated and stable without an output capacitor. However, a 10–100 µF electrolytic or ceramic capacitor is recommended to improve load transient response and reduce output impedance at high frequencies.
How does the SOA protection function during overload?
SOA protection dynamically limits the product of output current and input-output voltage differential to stay within the safe operating area of the internal pass transistor. This prevents second breakdown during sustained overload, unlike simple current limiting which ignores voltage stress.
Can L78S09CV-DG be used in automotive applications?
Yes - it meets AEC-Q100 stress testing requirements when used within its specified junction temperature range (0–150 °C) and with appropriate heatsinking. Its thermal shutdown, short-circuit robustness, and wide input range make it suitable for non-safety-critical automotive subsystems like body control modules.
L78S09CV-DG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 35V
- Voltage - Output (Min/Fixed):
- 9V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- Current - Output:
- 2A
- Current - Quiescent (Iq):
- 8 mA
- Current - Supply (Max):
- -
- PSRR:
- 47dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
L78S09CV-DG FAQ
1.How can I place an order for L78S09CV-DG through Aetrix?
Please submit a Request for Quotation (RFQ) for L78S09CV-DG 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 L78S09CV-DG reliable?
The price and inventory of L78S09CV-DG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78S09CV-DG is usually 5 days.
3.What payment methods are accepted for L78S09CV-DG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78S09CV-DG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L78S09CV-DG?
L78S09CV-DG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L78S09CV-DG 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 L78S09CV-DG?
For technical support, including L78S09CV-DG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78S09CV-DG requirements.
6.How does Aetrix verify that L78S09CV-DG is sourced from the original manufacturer or authorized distributors?
All L78S09CV-DG 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 L78S09CV-DG meets industry standards.
7.What is the process for return or replacement of L78S09CV-DG?
All L78S09CV-DG units undergo pre-shipment inspection (PSI). If there is an issue with L78S09CV-DG, 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 L78S09CV-DG part is unused and in its original packaging.
Return procedure for L78S09CV-DG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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