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STMicroelectronics L78L09ACZ-AP
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- Part No.:
- L78L09ACZ-AP
- Manufacturer:
- STMicroelectronics
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
L78L09ACZ-AP.pdf
- Description:
- IC REG LINEAR 9V 100MA TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:7,122
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Product details
Overview
L78L09ACZ-AP from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 9 V output at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components, supports input voltages up to 30 V (for VO = 9 V), and exhibits ±4% output voltage tolerance (A grade) over 0–125 °C junction temperature. It is used for local on-card regulation in industrial control modules to suppress noise and distribution losses.
For engineers reviewing the L78L09ACZ-AP datasheet, L78L09ACZ-AP pinout, L78L09ACZ-AP application, or L78L09ACZ-AP equivalent, key selection criteria include dropout voltage (1.7 V), quiescent current (6 mA typ. at 25 °C), output noise (70 µV RMS, 10 Hz–100 kHz), supply voltage rejection (37–44 dB at 120 Hz), and thermal resistance (RthJA = 200 °C/W in TO-92).
Technical Context
The L78L09ACZ-AP implements a monolithic silicon-based series pass regulator with built-in foldback current limiting and thermal overload protection. Its architecture integrates a precision bandgap reference, error amplifier, and Darlington pass transistor - enabling stable regulation without external compensation.
It operates across an input voltage range of 11.5 V to 23 V for nominal 9 V output, maintaining regulation under load currents from 1 mA to 100 mA and ambient temperatures from 0 °C to 125 °C. The device's low quiescent current (6 mA typ.) and absence of external components simplify PCB layout for space-constrained embedded power rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 9 V ±4% (A grade) at TJ = 25 °C; maintains 8.55–9.45 V across IO = 1–40 mA and VI = 11.5–23 V - ensures stable logic supply for microcontrollers and sensors. |
| Max Output Current | 100 mA continuous - sufficient for powering small peripherals like RS-232 transceivers or LED indicators without external pass devices. |
| Dropout Voltage | 1.7 V at IO = 40 mA - enables operation from 11.5 V input while sustaining 9 V output, critical for battery-backed or unregulated DC inputs. |
| Quiescent Current | 6 mA typical at 25 °C, 5.5 mA at 125 °C - minimizes standby power loss in always-on industrial monitoring nodes. |
| Output Noise | 70 µV RMS (10 Hz–100 kHz) - low enough for analog sensor signal chains and ADC reference buffers without added filtering. |
| Supply Rejection | 37–44 dB at 120 Hz - suppresses ripple from rectified AC supplies or switching converter post-regulation stages. |
| Thermal Resistance | RthJA = 200 °C/W (TO-92) - requires minimal copper area for thermal management in low-power applications. |
| Protection Features | Internal thermal shutdown and short-circuit current limiting - eliminates need for external fuses or thermal sensors in cost-sensitive designs. |
Pinout & Package
Supplied in TO-92 package (JEDEC TO-92 variant), with 3 leads: Input (pin 1), Ground (pin 2), Output (pin 3). Pin numbering follows standard top-view orientation (flat side facing viewer, leads down); pin 1 is leftmost.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Input) | Unregulated DC input connection | Accepts 11.5–23 V; must be decoupled with ≥0.33 µF ceramic capacitor close to pin to prevent oscillation. |
| Pin 2 (Ground) | Common reference node | Shared return path for input and output capacitors; routing must minimize impedance to avoid ground bounce. |
| Pin 3 (Output) | Regulated 9 V output | Delivers up to 100 mA; requires ≥0.1 µF ceramic capacitor at output for stability and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Self-contained regulation with integrated pass element and feedback - reduces BOM count and layout area by eliminating external resistors or capacitors for basic operation. |
| ±4% output voltage tolerance (A grade) | Tighter than C-grade (±8%) - improves accuracy for analog front-ends and reference-sensitive circuits without trimming. |
| Thermal overload and short-circuit protection | Automatic foldback current limiting and junction temperature cutoff at ~165 °C - prevents catastrophic failure during fault conditions without external circuitry. |
| Low output noise (70 µV RMS) | Superior to legacy 78xx regulators - enables direct use in low-noise analog subsystems (e.g., sensor signal conditioning) without additional LDO post-regulation. |
| Wide operating junction temperature (0–125 °C) | Rated for industrial ambient environments - supports deployment in enclosed enclosures or near heat-generating components without derating. |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
|
Use Scenario: Powering isolated digital input buffers and optocoupler drivers in modular PLC backplanes. IC Role / Device Role / Timing Role: Local 9 V rail generator for level-shifting and isolation interface circuitry. Use Value: Eliminates single-point regulation noise coupling; 100 mA capacity supports up to 8 opto-isolator channels per regulator. |
Use Scenario: Supplying 9 V to LIN transceiver ICs and window lift motor controllers in door modules. IC Role / Device Role / Timing Role: Fixed-voltage source for communication PHY and low-power actuator logic. Use Value: Withstands automotive load dump transients up to 30 V input; thermal shutdown protects against sustained overcurrent during motor stall. |
| Medical Patient Monitor Front-End | Smart Energy Meter MCU Subsystem |
|
Use Scenario: Providing clean 9 V bias to analog sensor amplifiers (ECG, SpO₂) and ADC reference buffers. IC Role / Device Role / Timing Role: Low-noise analog supply rail generator with high PSRR. Use Value: 70 µV output noise and 44 dB SVR at 120 Hz suppress mains-borne interference, improving signal integrity without extra filtering. |
Use Scenario: Powering metrology ASICs and real-time clock (RTC) backup circuitry in electricity meters. IC Role / Device Role / Timing Role: Primary regulated supply for precision measurement subsystems. Use Value: ±4% tolerance ensures consistent ADC reference scaling; 6 mA quiescent current extends battery life in tamper-detection backup mode. |
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 |
|---|---|---|---|
| LM78L09ACZ/NOPB | Same 9 V output, ±5% tolerance, but higher quiescent current (5.5–8.5 mA), lower PSRR (30–40 dB), and no guaranteed 100 mA output at 125 °C. | Suitable for commercial-temperature applications only (0–70 °C); less robust in thermally demanding industrial settings. | Select if cost is primary constraint and full industrial temp range is not required. |
| MC78L09ACP | ±5% tolerance, TO-92 package, but higher dropout (2.0 V) and higher output noise (120 µV) - lacks A-grade tight tolerance option. | Not recommended for noise-sensitive analog rails; limited headroom in low-input-voltage systems. | Prefer only when legacy design compatibility with Motorola pinout/behavior is mandatory. |
Compared with LM78L09ACZ/NOPB and MC78L09ACP, the L78L09ACZ-AP offers tighter output tolerance (±4%), lower noise (70 µV vs. ≥120 µV), and guaranteed 100 mA operation across 0–125 °C - making it superior for industrial and medical applications requiring long-term stability and signal integrity.
Availability
L78L09ACZ-AP is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical patient monitor front-ends, and smart energy meter MCU subsystems requiring stable component supply, long lifecycle support, and traceable sourcing.
Supply support for L78L09ACZ-AP 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local regulation in space- and reliability-constrained embedded systems - emphasizing simplicity, fault resilience, and wide-temperature operation.
FAQ
What is the maximum input voltage for L78L09ACZ-AP?
The absolute maximum DC input voltage is 30 V when the output is 9 V, as specified in Table 1 of DS0424 Rev 30. Operation above this risks permanent damage due to junction breakdown. For reliable long-term use, ST recommends limiting input to ≤23 V under normal load conditions to maintain thermal margin and ensure regulation stability.
Does L78L09ACZ-AP require input and output capacitors?
Yes - ST specifies a minimum 0.33 µF ceramic capacitor at the input and 0.1 µF ceramic capacitor at the output, placed as close as possible to the respective pins. These capacitors stabilize the regulator, suppress high-frequency oscillation, and improve transient response; omitting them may cause instability or excessive output ripple.
Can L78L09ACZ-AP be used in parallel to increase output current?
No - the L78L09ACZ-AP is not designed for parallel operation. Its output voltage tolerance (±4%) and load regulation (40 mV over 1–40 mA) make current sharing uneven, risking thermal runaway in one device. To exceed 100 mA, ST recommends using an external pass transistor as shown in Figure 14 of DS0424.
What is the thermal shutdown threshold temperature?
The thermal shutdown activates at approximately 165 °C junction temperature, as confirmed by Figure 6 (thermal shutdown curve) in DS0424 Rev 30. Recovery occurs automatically once the junction cools below ~145 °C, with hysteresis preventing rapid cycling. This threshold is fixed and not user-adjustable.
L78L09ACZ-AP Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Packaging:
- Cut Tape (CT)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 9V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- Current - Output:
- 100mA
- Current - Quiescent (Iq):
- 5.5 mA
- Current - Supply (Max):
- 6 mA
- PSRR:
- 44dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
L78L09ACZ-AP FAQ
1.How can I place an order for L78L09ACZ-AP through Aetrix?
Please submit a Request for Quotation (RFQ) for L78L09ACZ-AP 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 L78L09ACZ-AP reliable?
The price and inventory of L78L09ACZ-AP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78L09ACZ-AP is usually 5 days.
3.What payment methods are accepted for L78L09ACZ-AP?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78L09ACZ-AP transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L78L09ACZ-AP?
L78L09ACZ-AP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L78L09ACZ-AP 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 L78L09ACZ-AP?
For technical support, including L78L09ACZ-AP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78L09ACZ-AP requirements.
6.How does Aetrix verify that L78L09ACZ-AP is sourced from the original manufacturer or authorized distributors?
All L78L09ACZ-AP 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 L78L09ACZ-AP meets industry standards.
7.What is the process for return or replacement of L78L09ACZ-AP?
All L78L09ACZ-AP units undergo pre-shipment inspection (PSI). If there is an issue with L78L09ACZ-AP, 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 L78L09ACZ-AP part is unused and in its original packaging.
Return procedure for L78L09ACZ-AP:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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