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onsemi LM7912CT
- Part No.:
- LM7912CT
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
LM7912CT.pdf
- Description:
- LM79 3-TERMINAL, 1.5A NEGATIVE V
- Quantity:
- Payment:
- Shipping:
Inventory:1,117
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Product details
Overview
LM7912CT from Texas Instruments is a fixed-output, three-terminal negative voltage regulator delivering −12 V at up to 1.5 A output current with ±4% output voltage tolerance, 54–70 dB ripple rejection at 120 Hz, and thermal/short-circuit/safe-area protection. It operates across 0°C to +125°C junction temperature and is used in dual-rail power supplies, industrial control logic, and analog instrumentation requiring stable negative bias.
For engineers reviewing the LM7912CT datasheet, pinout, applications, or equivalent options, this page provides verified technical context, TO-220 package mapping, load/line regulation values, dropout voltage (1.1 V @ 1 A), and design-meaningful alternatives for −12 V linear regulation in embedded and industrial systems.
Technical Context
The LM7912CT implements a monolithic PNP pass transistor-based linear regulation architecture with internal current limiting, thermal shutdown, and safe-area compensation. Its fixed −12 V output is achieved without external feedback components, relying on trimmed on-die resistors and bandgap reference circuitry.
It requires only one external output capacitor (1 μF solid tantalum or ≥25 μF aluminum electrolytic) for stability and exhibits low ground pin current (1.5–3 mA typical), enabling straightforward output voltage boosting via resistor dividers. Input voltage range is −14.5 V to −30 V under full-load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −12.0 V nominal, −11.4 V to −12.6 V over full load/temperature range - ensures compatibility with TTL/CMOS logic and op-amp dual-supply rails. |
| Output Current | 1.5 A continuous - supports medium-power analog stages and digital subsystems without external pass devices. |
| Ripple Rejection | 54–70 dB at 120 Hz - suppresses rectified AC noise in unregulated DC inputs, critical for low-noise sensor front-ends. |
| Dropout Voltage | 1.1 V at 1 A load - defines minimum input-to-output differential needed to maintain regulation; impacts heatsink sizing and efficiency. |
| Line Regulation | 3–80 mV over −30 V to −14.5 V input - quantifies sensitivity to raw supply variation; lower values reduce need for upstream filtering. |
| Load Regulation | 15–200 mV over 5 mA to 1.5 A - determines output stability across dynamic current demands, e.g., microcontroller sleep/wake transitions. |
| Quiescent Current | 1.5–3 mA - contributes directly to no-load power loss; enables predictable standby consumption in battery-backed systems. |
Pinout & Package
LM7912CT is housed in a TO-220 package (Package Drawing NDE0003B) with integral heat sink tab electrically connected to the common (ground) terminal. The case serves as both thermal path and electrical return, requiring insulated mounting hardware when mounted to grounded chassis.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Input | Negative input supply connection | Accepts unregulated negative DC; must be ≥ −14.5 V to sustain −12 V output under 1.5 A load. |
| Ground | Common reference and heat sink tab | Electrical 0 V reference; also primary thermal conduction path - must be thermally coupled to heatsink with low-θCA. |
| Output | Regulated −12 V source | Delivers stable negative rail; requires ≥1 μF output capacitance (tantalum) for stability and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| Thermal shutdown protection | Activates at ~125°C junction temperature to prevent permanent damage during overload or inadequate heatsinking. |
| Internal short-circuit current limit | Clamps peak output to ~2.2 A, protecting both regulator and downstream circuitry during fault conditions. |
| Low ground pin current | 1.5–3 mA typical enables precise output voltage boosting using external resistor dividers without significant error. |
| High ripple rejection | ≥54 dB at 120 Hz reduces residual AC content on regulated rail - essential for audio preamps and precision ADC references. |
| Fixed −12 V output | Eliminates external feedback network, reducing BOM count and layout complexity versus adjustable regulators. |
Applications
| Industrial PLC I/O Modules | Analog Sensor Signal Conditioning |
|---|---|
Use Scenario: Powering isolated analog input channels in programmable logic controllers with ±15 V or ±12 V dual supplies. IC Role / Device Role / Timing Role: Negative rail generator providing stable −12 V for op-amp bias and ADC reference circuits. Use Value: Maintains <±0.1% output drift over temperature and load, ensuring consistent 12-bit+ measurement accuracy. |
Use Scenario: Supplying dual-rail op-amps in bridge amplifier or strain-gauge signal chains operating from unregulated wall adapters. IC Role / Device Role / Timing Role: Fixed negative voltage source enabling rail-to-rail input swing and low-noise amplification. Use Value: 300 μV RMS output noise (10 Hz–100 Hz) preserves small-signal integrity in µV-level sensor outputs. |
| Dual-Rail Audio Preamps | Legacy TTL/CMOS Logic Bias |
Use Scenario: Generating symmetric ±12 V supplies for discrete transistor or op-amp based microphone preamplifiers. IC Role / Device Role / Timing Role: Negative supply regulator maintaining headroom and minimizing crossover distortion in Class-A stages. Use Value: 70 dB ripple rejection suppresses 120 Hz hum from transformer-rectifier inputs, critical for low-THD performance. |
Use Scenario: Providing −12 V bias for vintage TTL bus drivers, ECL logic families, or RS-232 transceivers requiring negative voltage levels. IC Role / Device Role / Timing Role: Fixed negative rail generator meeting legacy interface voltage specifications. Use Value: ±4% output tolerance ensures reliable logic level compliance across temperature and line variations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed negative voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM337T | Adjustable output (−1.25 V to −37 V); requires two external resistors; 1.5 A max; higher quiescent current (5 mA typical). | Used where variable or non-standard negative voltages (e.g., −8.5 V, −18 V) are required; less suitable for cost-sensitive fixed-voltage designs. | Select LM337T only if output voltage flexibility outweighs added component count and reduced accuracy vs. LM7912CT's factory-trimmed −12 V. |
| MC7912CD2TR4G | Same −12 V output, 1.5 A rating, TO-220 package; tighter initial tolerance (±2%); RoHS-compliant; higher ripple rejection (72 dB typical). | Preferred for new designs requiring extended lifecycle support and improved noise performance; pin-compatible but not identical marking or thermal resistance. | Choose MC7912CD2TR4G for high-reliability industrial deployments where tighter tolerance and enhanced ripple suppression justify sourcing from ON Semiconductor. |
Compared with LM7912CT, LM337T offers voltage adjustability at the cost of accuracy and BOM complexity, while MC7912CD2TR4G delivers tighter tolerance and superior ripple rejection in a drop-in compatible TO-220 package-making it a direct upgrade path for noise-sensitive or long-lifecycle applications.
Availability
LM7912CT is available at Aetrix Electronics and suitable for industrial control systems, analog instrumentation, dual-rail audio circuits, and legacy logic interface designs requiring stable component supply and long-term obsolescence management.
Supply support for LM7912CT 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 power management ICs, with decades of expertise in linear regulation and power system design.
The LM79XX series was engineered for robust, low-cost, fixed-voltage negative regulation in industrial, automotive, and communications equipment - prioritizing thermal resilience, fault protection, and ease of use over programmability.
FAQ
What is the maximum input voltage for LM7912CT?
The absolute maximum input voltage for LM7912CT is −35 V when regulating −12 V output. For reliable operation within specifications, the recommended input range is −14.5 V to −30 V. Exceeding −35 V risks permanent damage due to internal junction breakdown, regardless of thermal management. Always verify input ripple and transient spikes remain within this limit in the final design.
Does LM7912CT require an input bypass capacitor?
Yes, LM7912CT requires a minimum 2.2 μF input bypass capacitor (ceramic or solid tantalum) placed close to the input pin to suppress high-frequency noise and prevent oscillation. Aluminum electrolytics may be substituted if ≥10 μF. Without this capacitor, the regulator may exhibit instability or degraded ripple rejection, especially with long input traces or high-impedance sources.
Can LM7912CT be used in parallel for higher current?
No, LM7912CT is not designed for parallel operation. Its output voltage tolerance (±4%) and lack of current-sharing features mean unequal load distribution - one device will dominate conduction, risking thermal runaway and premature failure. For >1.5 A, use a single higher-current regulator or switch-mode solution instead of paralleling LM7912CT units.
What is the thermal resistance of LM7912CT in TO-220 package?
LM7912CT in TO-220 package has a typical junction-to-case thermal resistance (θJC) of 3.0°C/W and maximum of 5.0°C/W. Junction-to-ambient (θJA) is 60°C/W without heatsink and 40°C/W with proper heatsinking. These values determine required heatsink size to keep junction temperature ≤125°C under worst-case power dissipation (e.g., 12 W at 1 A with 12 V dropout).
Is LM7912CT RoHS compliant?
Yes, the LM7912CT/NOPB variant is RoHS compliant and lead-free, with Green (low-halogen) finish per TI's packaging specification. Standard LM7912CT (non-NOPB) is marked NRND in TI's packaging addendum and may not meet current RoHS requirements; always specify LM7912CT/NOPB for new designs requiring environmental compliance.
LM7912CT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Bulk
- Product Status:
- Active
- 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):
- 2V @ 1A (Typ)
- Current - Output:
- 1A
- Current - Quiescent (Iq):
- 6 mA
- Current - Supply (Max):
- -
- PSRR:
- 60dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-3
LM7912CT FAQ
1.How can I place an order for LM7912CT through Aetrix?
Please submit a Request for Quotation (RFQ) for LM7912CT 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 LM7912CT reliable?
The price and inventory of LM7912CT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM7912CT is usually 5 days.
3.What payment methods are accepted for LM7912CT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM7912CT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM7912CT?
LM7912CT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM7912CT 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 LM7912CT?
For technical support, including LM7912CT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM7912CT requirements.
6.How does Aetrix verify that LM7912CT is sourced from the original manufacturer or authorized distributors?
All LM7912CT 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 LM7912CT meets industry standards.
7.What is the process for return or replacement of LM7912CT?
All LM7912CT units undergo pre-shipment inspection (PSI). If there is an issue with LM7912CT, 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 LM7912CT part is unused and in its original packaging.
Return procedure for LM7912CT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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