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STMicroelectronics LF85CPT-TR
- Part No.:
- LF85CPT-TR
- Manufacturer:
- STMicroelectronics
- Package:
- TO-252-5, DPAK (4 Leads + Tab), TO-252AD
- Datasheet:
-
LF85CPT-TR.pdf
- Description:
- IC REG LINEAR 8.5V 500MA PPAK
- Quantity:
- Payment:
- Shipping:
Inventory:4,327
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Product details
Overview
LF85CPT-TR from STMicroelectronics is a very low-dropout linear voltage regulator with logic-controlled shutdown, delivering 8.5 V output at up to 500 mA, featuring 0.45 V dropout (at 200 mA), ±2% output accuracy (C grade), and operation across –40 °C to 125 °C. It is an automotive-grade PPAK-packaged LDO used as a local power supply in engine control units and ADAS domain controllers where low quiescent current (50 µA in OFF mode) and high PSRR (82 dB at 120 Hz) are critical.
For engineers reviewing the LF85CPT-TR datasheet, LF85CPT-TR pinout, LF85CPT-TR application, or LF85CPT-TR equivalent, this page provides verified electrical specs, thermal data, shutdown interface behavior, stability requirements (2.2 µF ceramic output cap), and AEC-Q100-compliant use cases for automotive embedded systems.
Technical Context
The LF85CPT-TR implements a PNP pass transistor architecture enabling ultra-low dropout and stable regulation under transient load steps. Its internal current and thermal limiting protect against fault conditions without external circuitry, and the TTL-compatible inhibit input (Pin 2) allows precise system-level power sequencing.
Designed for automotive environments, it meets AEC-Q100 Grade 1 qualification with PAT, SYL, and SBL statistical testing. The device operates with only 2.2 µF output capacitance (ESR 0.1–10 Ω), reducing board area and cost versus legacy LDOs requiring ≥10 µF tantalum or electrolytic capacitors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 8.5 V ±2% at 25 °C (C grade); supports precision biasing of 8 V–9 V analog sensors and microcontrollers |
| Dropout Voltage | 0.45 V typical at 200 mA; enables regulation from 9 V input down to 8.5 V output - critical for cold-crank battery scenarios |
| Quiescent Current | 50 µA in OFF mode; reduces standby power in always-on vehicle modules like CAN gateways |
| PSRR | 82 dB at 120 Hz; suppresses alternator ripple and switching noise before sensitive ADCs or RF receivers |
| Output Current | 500 mA continuous; sufficient to power single-core MCUs, CAN transceivers, and sensor signal chains |
| Operating Temp | –40 °C to +125 °C junction; qualified per AEC-Q100 for under-hood and transmission-control applications |
| Stability Cap | 2.2 µF ceramic (ESR 0.1–10 Ω); eliminates need for bulky, temperature-sensitive electrolytics |
Pinout & Package
LF85CPT-TR is housed in a thermally enhanced PPAK (Power Package) with exposed thermal pad electrically connected to GND. This 5-pin surface-mount package supports high-power dissipation in compact automotive PCB layouts and enables automated optical inspection (AOI) compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 – IN | Input voltage supply | Accepts 9–16 V DC input; internal overvoltage clamp activates above 40 V |
| 2 – INH | Inhibit control input | TTL-compatible shutdown pin; <0.8 V = OFF (50 µA IQ), >2 V = ON (500 µA IQ) |
| 3 – GND | Ground reference | Common return path; electrically tied to exposed thermal pad for optimal heat transfer |
| 4 – OUT | Regulated output | Delivers stable 8.5 V ±2%; requires 2.2 µF ceramic capacitor on PCB for loop stability |
| 5 – TAB | Thermal pad / GND | Exposed copper pad soldered to PCB ground plane; contributes to RthJA = 100 °C/W |
Key Features
| Feature | Design Value |
|---|---|
| Logic-controlled shutdown | Enables system-level power gating via MCU GPIO - reduces total module standby current by >99% |
| AEC-Q100 qualified | Validated for automotive Grade 1 (–40 °C to +125 °C) with full statistical reliability testing (PAT/SYL/SBL) |
| Low-noise regulation | 50 µV RMS output noise (10 Hz–100 kHz) preserves SNR in precision analog front-ends |
| Internal protection | Integrated current limit and thermal shutdown eliminate need for external foldback or thermal sensors |
| Minimal external components | Only two capacitors required: 0.1 µF input + 2.2 µF output - simplifies layout and BOM |
Applications
| Engine Control Unit (ECU) | ADAS Domain Controller |
|---|---|
Use Scenario: Powering 8-bit/32-bit MCUs, fuel injector drivers, and knock sensor amplifiers in gasoline/diesel ECUs. IC Role / Device Role / Timing Role: Primary 8.5 V local regulator supplying core logic and analog peripherals; shutdown synchronized with ignition-off state. Use Value: Maintains regulation during cold-crank (down to 6.5 V battery), while 50 µA OFF-mode current prevents battery drain over weeks of vehicle inactivity. | Use Scenario: Biasing radar MMICs, camera ISP cores, and CAN FD transceivers in centralized ADAS compute modules. IC Role / Device Role / Timing Role: Secondary LDO providing clean 8.5 V rail isolated from noisy main 12 V supply; enabled only during active sensor fusion cycles. Use Value: 82 dB PSRR rejects switching noise from adjacent DC/DC converters, preventing false radar detections or image artifacts. |
| Body Control Module (BCM) | Electric Power Steering (EPS) |
Use Scenario: Supplying LIN transceivers, door lock actuators, and ambient light sensor interfaces in distributed body electronics. IC Role / Device Role / Timing Role: Always-on LDO with programmable inhibit; powers wake-up circuitry and retains configuration memory during sleep. Use Value: ±2% output tolerance ensures reliable LIN bus signaling across temperature and battery aging; 2.2 µF cap saves space in tight BCM housings. | Use Scenario: Regulating power to torque-sensing ASICs and motor phase current sense amplifiers in EPS electronic control units. IC Role / Device Role / Timing Role: Safety-critical auxiliary LDO feeding functional safety monitors (ASIL-B compliant subsystems). Use Value: Internal thermal/current limits prevent latch-up during motor stall events; AEC-Q100 qualification supports ISO 26262 hardware confidence metrics. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LDL112PU33R | 3.3 V fixed output, 200 mA max, 170 mV dropout, SOT-323 package | Lower current, lower voltage; suited for low-power MCU cores, not 8.5 V analog rails | Select only if target voltage is 3.3 V and thermal budget permits smaller package |
| TLE42754G | 5 V fixed output, 450 mA, 300 mV dropout, TO-252 package, integrated reset flag | Different output voltage and monitoring features; lacks 8.5 V option and PPAK thermal performance | Choose when system requires built-in reset generation and 5 V rail - not for 8.5 V use cases |
Compared with LDL112PU33R and TLE42754G, LF85CPT-TR uniquely delivers 8.5 V output in an AEC-Q100-qualified PPAK package with 0.45 V dropout and 50 µA OFF-mode current - making it the only direct fit for automotive 8–9 V analog subsystems requiring minimal board area and high thermal efficiency.
Availability
LF85CPT-TR is available at Aetrix Electronics and suitable for engine control units, ADAS domain controllers, body control modules, and electric power steering systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LF85CPT-TR 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 microcontrollers, power management ICs, sensors, and automotive-grade analog devices.
The LFXX series was developed specifically for automotive power management, targeting high-reliability, low-quiescent-current LDO applications in harsh under-hood and chassis-mounted electronic control units.
FAQ
What is the minimum input voltage required for regulation at 8.5 V output?
The LF85CPT-TR maintains regulation as long as input voltage exceeds output voltage plus dropout. With a typical dropout of 0.45 V at 200 mA, the minimum input is 8.95 V. At 500 mA, dropout rises to 0.7 V, requiring ≥9.2 V input. Below these thresholds, output voltage drops linearly with input.
Can the INH pin be left floating, or must it be actively driven?
The INH pin must never be left floating: its internal structure lacks a pull-up or pull-down, so undefined logic levels may cause erratic ON/OFF transitions. For always-on operation, tie INH to VIN through a 10 kΩ resistor; for controlled shutdown, drive it directly from a GPIO with 0.8 V/2 V thresholds.
Is the exposed thermal pad (Pin 5) required to be soldered to PCB ground?
Yes - the TAB is electrically connected to GND and serves as the primary thermal conduction path. Omitting solder paste or thermal vias under the pad increases junction-to-ambient thermal resistance from 100 °C/W to >150 °C/W, risking thermal shutdown at ≤300 mA load in still air.
Does LF85CPT-TR support adjustable output voltage via external resistors?
No - LF85CPT-TR is a fixed-output 8.5 V regulator. STMicroelectronics does not offer an adjustable variant in the LFXX family. Output voltage is laser-trimmed during wafer test and cannot be modified externally; alternative fixed-voltage variants (e.g., LF33CPT-TR, LF50CPT-TR) are available for other rails.
LF85CPT-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-252-5, DPAK (4 Leads + Tab), TO-252AD
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 8.5V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.7V @ 500mA
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 1.5 mA
- Current - Supply (Max):
- 12 mA
- PSRR:
- 72dB ~ 57dB (120Hz ~ 10kHz)
- Control Features:
- Enable
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- PPAK
LF85CPT-TR FAQ
1.How can I place an order for LF85CPT-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for LF85CPT-TR 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 LF85CPT-TR reliable?
The price and inventory of LF85CPT-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LF85CPT-TR is usually 5 days.
3.What payment methods are accepted for LF85CPT-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LF85CPT-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LF85CPT-TR?
LF85CPT-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LF85CPT-TR 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 LF85CPT-TR?
For technical support, including LF85CPT-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LF85CPT-TR requirements.
6.How does Aetrix verify that LF85CPT-TR is sourced from the original manufacturer or authorized distributors?
All LF85CPT-TR 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 LF85CPT-TR meets industry standards.
7.What is the process for return or replacement of LF85CPT-TR?
All LF85CPT-TR units undergo pre-shipment inspection (PSI). If there is an issue with LF85CPT-TR, 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 LF85CPT-TR part is unused and in its original packaging.
Return procedure for LF85CPT-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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