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STMicroelectronics L79L12ACD
- Part No.:
- L79L12ACD
- Manufacturer:
- STMicroelectronics
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
L79L12ACD.pdf
- Description:
- IC REG LINEAR -12V 100MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,766
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Product details
Overview
L79L12ACD from STMicroelectronics is a three-terminal fixed negative voltage regulator delivering -12 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components and is designed for local on-card regulation in industrial control, embedded power supplies, and noise-sensitive analog subsystems.
For engineers reviewing the L79L12ACD datasheet, L79L12ACD pinout, L79L12ACD application, or L79L12ACD equivalent, this device serves as a drop-in replacement for Zener diode/resistor regulators-offering two orders of magnitude lower output impedance, reduced quiescent current (6.5 mA typ.), and 80 µV RMS output noise (10 Hz–100 kHz).
Technical Context
The L79L12ACD operates as a monolithic linear regulator with built-in thermal shutdown and foldback current limiting. Its dropout voltage is fixed at 1.7 V, enabling stable regulation when input is as low as -13.7 V under full load.
It supports operation across 0 °C to +125 °C junction temperature and achieves ±5% output voltage tolerance at 25 °C (–11.5 V to –12.5 V). Supply voltage rejection is 37–42 dB at 120 Hz with VI = –15 V to –25 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | –12 V nominal; –11.5 V to –12.5 V over temperature (±5% AC grade) |
| Max Output Current | 100 mA continuous; limited by internal current foldback and thermal shutdown |
| Dropout Voltage | 1.7 V typical; defines minimum VIN–VO differential needed for regulation |
| Quiescent Current | 6.5 mA typical at 25 °C; enables low-power standby operation |
| Output Noise | 80 µV RMS (10 Hz–100 kHz); critical for precision analog and sensor supply rails |
| Line Regulation | 200 mV max over VI = –14.5 V to –27 V; ensures stability against input ripple |
| Load Regulation | 100 mV max over IO = 1–100 mA; maintains accuracy across full load range |
Pinout & Package
Supplied in SO-8 package with pins 2, 3, 6, and 7 internally connected to the die attach flag for enhanced thermal performance (Rthj-case = 20 °C/W). Requires ≥6 cm² copper pour for optimal heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | GND | Ground reference terminal; connects to PCB ground plane and thermal pad |
| Pin 2 | VIN | Negative input terminal; accepts –14.5 V to –27 V DC input |
| Pin 3 | VOUT | Regulated negative output; delivers –12 V to load with <100 mV load regulation |
| Pins 4–5, 7–8 | No Connect / Thermal Flag | Internally tied to die attach flag; must be soldered to large copper area for thermal management |
Key Features
| Feature | Design Value |
|---|---|
| Thermal Overload Protection | Automatic shutdown above safe junction temperature; self-recovery on cooldown |
| Short-Circuit Protection | Foldback current limiting prevents damage during sustained output shorts |
| No External Components | Operates stand-alone with only input/output capacitors (0.33 µF CI, 0.1 µF CO) |
| Low Output Impedance | ~100× lower than Zener/resistor equivalents; improves PSRR and transient response |
| Wide Operating Temperature | 0 °C to +125 °C junction range; qualified for industrial-grade reliability |
Applications
| Industrial Sensor Signal Conditioning | Embedded Microcontroller Power Rail |
|---|---|
Use Scenario: Providing clean, stable bias for op-amps and ADC references in factory-floor pressure/temperature transmitters. IC Role / Device Role / Timing Role: Negative rail generator for dual-supply analog front-ends requiring low-noise –12 V. Use Value: 80 µV RMS noise and 42 dB SVR suppress switching noise from adjacent DC-DC converters. |
Use Scenario: Local regulation for microcontroller I/O banks and peripheral interfaces in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: On-board negative voltage source for RS-232 transceivers and level-shifting circuits. Use Value: 100 mA capability and thermal shutdown ensure robust operation during transient overloads in unattended systems. |
| Legacy Analog Instrumentation | Test & Measurement Equipment |
Use Scenario: Replacing aging Zener/resistor networks in calibrated multimeters and oscilloscope front-ends. IC Role / Device Role / Timing Role: Precision negative reference generator with improved long-term stability. Use Value: ±5% output tolerance and <100 mV load regulation maintain calibration integrity across operating conditions. |
Use Scenario: Biasing active filters and DAC output stages in benchtop signal generators and spectrum analyzers. IC Role / Device Role / Timing Role: Low-noise auxiliary supply for high-resolution analog signal paths. Use Value: Two-order-of-magnitude lower output impedance reduces interaction between channels and improves crosstalk rejection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7912CD | ±5% tolerance, 1.7 V dropout, but higher quiescent current (6.8 mA typ.) and 120 µV noise | Wider ambient temp range (–40 °C to +125 °C), but lower PSRR (35 dB) | Prefer where extended temperature operation is required and noise is less critical |
| MC79L12ACDR2G | SO-8 package, ±5% tolerance, 1.7 V dropout, 75 µV noise, but Rthj-amb = 220 °C/W (no thermal flag) | Lower noise than L79L12ACD but significantly poorer thermal performance without PCB heatsinking | Choose only with verified board-level thermal design; avoid in space-constrained or high-ambient environments |
Compared with LM7912CD and MC79L12ACDR2G, the L79L12ACD offers superior thermal management via its internal flag connection and best-in-class noise performance-making it optimal for compact, noise-sensitive industrial analog designs where board-level copper area is available for heatsinking.
Availability
L79L12ACD is available at Aetrix Electronics and suitable for industrial sensor conditioning, embedded microcontroller power rails, and test equipment requiring stable component supply with guaranteed long-term continuity.
Supply support for L79L12ACD 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, specializing in automotive, industrial, and power management ICs with strong emphasis on reliability and longevity.
The L79L00 series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained industrial and instrumentation applications requiring robust fixed-voltage regulation without external pass elements.
FAQ
What is the maximum input voltage for L79L12ACD?
The absolute maximum DC input voltage is –35 V when VO = –12 V. For reliable operation, ST recommends keeping VI ≤ –27 V under full load to maintain thermal safety margin. Exceeding –35 V risks permanent damage due to internal junction breakdown.
Can L79L12ACD be used in parallel for higher current?
No-L79L12ACD lacks current-sharing circuitry and has no guaranteed matching between units. Parallel connection may cause thermal runaway or uneven current distribution. For >100 mA, use an external pass transistor with proper biasing per ST Application Note AN457.
Is a heat sink required for 100 mA operation?
Yes-when delivering 100 mA at worst-case dropout (1.7 V), power dissipation reaches ~170 mW. With Rthj-amb = 55 °C/W (SO-8, 6 cm² copper), junction temperature rise is ~9.4 °C. A minimal copper pour is sufficient, but no discrete heat sink is needed unless ambient exceeds 115 °C.
What capacitor values are recommended for stable operation?
ST specifies 0.33 µF aluminum or tantalum at the input (CI) and 0.1 µF ceramic at the output (CO). These values ensure phase margin >45° and prevent oscillation. Larger CO (>1 µF) may improve transient response but requires verification per Figure 12 in the datasheet.
L79L12ACD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Negative
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- -35V
- Voltage - Output (Min/Fixed):
- -12V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- Current - Output:
- 100mA
- Current - Quiescent (Iq):
- 6 mA
- Current - Supply (Max):
- 6.5 mA
- PSRR:
- 42dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
L79L12ACD FAQ
1.How can I place an order for L79L12ACD through Aetrix?
Please submit a Request for Quotation (RFQ) for L79L12ACD 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 L79L12ACD reliable?
The price and inventory of L79L12ACD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L79L12ACD is usually 5 days.
3.What payment methods are accepted for L79L12ACD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L79L12ACD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L79L12ACD?
L79L12ACD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L79L12ACD 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 L79L12ACD?
For technical support, including L79L12ACD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L79L12ACD requirements.
6.How does Aetrix verify that L79L12ACD is sourced from the original manufacturer or authorized distributors?
All L79L12ACD 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 L79L12ACD meets industry standards.
7.What is the process for return or replacement of L79L12ACD?
All L79L12ACD units undergo pre-shipment inspection (PSI). If there is an issue with L79L12ACD, 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 L79L12ACD part is unused and in its original packaging.
Return procedure for L79L12ACD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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