My Inquiry
My Account
STMicroelectronics L4945
- Part No.:
- L4945
- Manufacturer:
- STMicroelectronics
- Package:
- TO-220-3
- Datasheet:
-
L4945.pdf
- Description:
- IC REG LINEAR 5V 500MA TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:4,974
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
L4945 from STMicroelectronics is a monolithic 5V low-dropout linear voltage regulator in Versawatt (TO-220) package, designed for automotive and industrial systems. It delivers precise ±4% output voltage (4.8–5.2 V) over –40°C to +125°C, supports up to 500 mA load current, maintains ≤0.75 V dropout at full temperature range and full load, and integrates reverse-voltage, overvoltage, short-circuit, and thermal shutdown protections.
For engineers reviewing the L4945 datasheet, L4945 pinout, L4945 application, or L4945 equivalent, this regulator's crank-phase operation down to 6 V input, ±80 V load-dump tolerance, and external 47 µF/ESR < 10 Ω output capacitor requirement are critical selection criteria in battery-rail power design.
Technical Context
The L4945 uses a lateral PNP pass transistor to achieve ultra-low dropout (0.4–0.75 V), enabling stable 5 V regulation even during automotive cranking when battery voltage drops to 6 V. Its three-stage gain architecture (reference, error amplifier, driver) requires external compensation with ≥47 µF output capacitance (ESR < 10 Ω) for loop stability.
Protection circuitry includes field-decay and load-dump immunity (±80 V, 300 ms), –18 V reverse-input tolerance, current-limited short-circuit response (0.5–1.5 A), and thermal shutdown with hysteresis-ensuring robustness on noisy vehicle battery rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 5.0 V ±4% (4.8–5.2 V) over –40°C to +125°C - ensures logic-level compatibility across full automotive temperature range |
| Max Dropout Voltage | 0.75 V @ 500 mA, full temperature range - enables operation with input as low as 6 V during engine cranking |
| Load Current | Up to 500 mA continuous - sufficient for MCU core supplies, sensor interfaces, and CAN transceivers |
| Input Voltage Range | 6–26 V DC - compatible with 12 V automotive systems including transient overvoltage conditions |
| Quiescent Current | 10 mA max over full temperature range - minimizes standby power loss in always-on modules |
| Protection Features | Reverse-voltage (–18 V), load-dump (±80 V/300 ms), short-circuit, and thermal shutdown with hysteresis - eliminates need for external protection circuitry |
| Supply Rejection | 50–60 dB @ 120 Hz - suppresses ripple from alternator and switching noise in vehicle power nets |
Pinout & Package
Versawatt (TO-220) package with integral heat sink tab; thermally optimized for PCB mounting with case-to-ambient Rth ≈ 3 °C/W (junction-to-case).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Input) | Regulator Input | Accepts 6–26 V DC; must withstand ±80 V transients and –18 V reverse polarity |
| 2 (Ground) | Reference and Power Return | Common return path for control circuitry and pass transistor emitter; tied to heat sink tab |
| 3 (Output) | Stabilized 5 V Output | Delivers regulated 5 V to load; requires ≥47 µF/ESR < 10 Ω ceramic or tantalum capacitor to ground |
Key Features
| Feature | Design Value |
|---|---|
| Lateral PNP pass element | Enables 0.4 V typical / 0.75 V max dropout at 500 mA - sustains regulation during low-battery cranking |
| Integrated protection suite | Eliminates need for discrete TVS, reverse-polarity diode, and current-limiting FET in automotive BOM |
| External capacitor stabilization | Supports wide-range output capacitors (≥47 µF, ESR < 10 Ω) - accommodates aging and temperature drift in production |
| Thermal shutdown with hysteresis | Prevents latch-up during sustained overload; allows safe auto-recovery after cooling without system reset |
| ESD protection | MIL-STD-883C compliant - withstands handling and assembly without additional ESD safeguards |
Applications
| Engine Control Unit (ECU) Power Supply | Body Control Module (BCM) Logic Rail |
|---|---|
Use Scenario: Powers microcontroller, CAN interface, and analog sensors in under-hood ECU exposed to wide ambient temperature swings and battery transients. IC Role / Device Role / Timing Role: Primary 5 V linear regulator supplying core logic and I/O; operates continuously during cranking and hot-soak conditions. Use Value: Maintains 5 V output with ≤0.75 V dropout at 500 mA even when battery sags to 6 V - prevents brownout resets during engine start. | Use Scenario: Supplies 5 V to door module MCUs, LIN transceivers, and LED drivers in passenger compartment electronics. IC Role / Device Role / Timing Role: Main system rail regulator; handles intermittent loads and reverse-battery fault events during service. Use Value: Integrated –18 V reverse-voltage protection avoids destructive current flow during battery terminal misconnection. |
| Instrument Cluster Display Driver | Telematics Control Unit (TCU) Standby Regulator |
Use Scenario: Provides clean 5 V to TFT display controller and backlight ICs in dashboard clusters subject to load-dump spikes. IC Role / Device Role / Timing Role: Secondary regulated rail isolated from main 12 V bus; absorbs ±80 V/300 ms load-dump energy. Use Value: Withstands ISO 7637-2 Pulse 5a/b without external clamping - reduces board space and BOM count. | Use Scenario: Powers real-time clock, GPS receiver, and cellular modem sleep circuitry in always-on telematics units. IC Role / Device Role / Timing Role: Low-quiescent-current (≤10 mA) standby regulator maintaining memory and wake-up logic during vehicle off-state. Use Value: Enables <10 mA total system sleep current - extends battery life during extended parking without parasitic drain. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 5 V automotive LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL750L05 | Higher dropout (1.2 V typ.), no integrated load-dump protection, TO-220 package | Lacks ±80 V transient immunity - requires external TVS and reverse-polarity protection | Lower cost where ISO 7637-2 compliance is not required and board space permits discrete protection |
| LD1085V50 | Higher quiescent current (12 mA), no reverse-voltage protection, same TO-220 footprint | Not rated for –18 V reverse input - unsuitable for service environments with battery misconnection risk | Acceptable for non-automotive industrial use with controlled power-up sequencing and external polarity protection |
Compared with TL750L05 and LD1085V50, the L4945 uniquely combines crank-phase operation (6 V min input), integrated ±80 V load-dump immunity, and –18 V reverse-voltage tolerance - making it the only single-package solution meeting full automotive OEM requirements without supplemental protection components.
Availability
L4945 is available at Aetrix Electronics and suitable for engine control units, body control modules, instrument clusters, and telematics control units requiring stable component supply in automotive-grade production environments.
Supply support for L4945 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.
The L4945 belongs to ST's automotive-grade linear regulator product line, engineered specifically for harsh-environment 12 V battery-rail applications requiring high transient immunity and cranking-phase reliability.
FAQ
What is the minimum input voltage required for L4945 to maintain 5 V output at 500 mA?
The L4945 requires a minimum input voltage of 5.75 V to sustain 5 V output at 500 mA load, based on its maximum 0.75 V dropout specification across –40°C to +125°C. In practice, 6 V is recommended to ensure margin against temperature drift and line regulation error.
Can L4945 be used without an output capacitor?
No. The L4945 requires a minimum 47 µF output capacitor with ESR < 10 Ω for loop stability, as confirmed by ST's test circuit and external compensation guidelines. Omitting it risks oscillation, output overshoot, and thermal instability under load transients.
Does L4945 support adjustable output voltage via feedback resistors?
No. The L4945 is a fixed 5 V output device with internal reference and error amplifier. It does not provide an adjust pin or external feedback capability - output voltage is trimmed at wafer level and cannot be modified externally.
Is L4945 qualified to AEC-Q100 standards?
While the L4945 was designed for automotive applications and incorporates AEC-Q100-relevant features (e.g., –40°C to +125°C operation, load-dump immunity), STMicroelectronics documentation does not list formal AEC-Q100 qualification for this specific part number; it is classified as an automotive-grade component but not certified.
L4945 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):
- 26V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.75V @ 500mA
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 13 mA
- Current - Supply (Max):
- 180 mA
- PSRR:
- 60dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Over Voltage, Reverse Polarity, Short Circuit
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
L4945 FAQ
1.How can I place an order for L4945 through Aetrix?
Please submit a Request for Quotation (RFQ) for L4945 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 L4945 reliable?
The price and inventory of L4945 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4945 is usually 5 days.
3.What payment methods are accepted for L4945?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4945 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L4945?
L4945 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L4945 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 L4945?
For technical support, including L4945 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4945 requirements.
6.How does Aetrix verify that L4945 is sourced from the original manufacturer or authorized distributors?
All L4945 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 L4945 meets industry standards.
7.What is the process for return or replacement of L4945?
All L4945 units undergo pre-shipment inspection (PSI). If there is an issue with L4945, 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 L4945 part is unused and in its original packaging.
Return procedure for L4945:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
L4945 Tags
-
MIC5504-1.8YM5-TR
Microchip Technology
-
MIC5504-3.3YM5-TR
Microchip Technology
-
MIC5365-3.0YC5-TR
Microchip Technology
-
MIC5365-1.8YC5-TR
Microchip Technology
-
MIC5365-2.5YC5-TR
Microchip Technology
-
MIC5365-3.3YC5-TR
Microchip Technology
-
MIC5365-3.3YD5-TR
Microchip Technology
-
MIC5317-3.3YM5-TR
Microchip Technology
-
TLV1117LV33DCYR
Texas Instruments
-
MIC5317-3.3YMT-TZ
Microchip Technology
-
MIC5528-3.3YMT-TR
Microchip Technology
-
TLV75801PDRVR
Texas Instruments
Tech Hub
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…
Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…
Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.
18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…
