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STMicroelectronics LF85CDT-TR
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- Part No.:
- LF85CDT-TR
- Manufacturer:
- STMicroelectronics
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
LF85CDT-TR.pdf
- Description:
- IC REG LINEAR 8.5V 500MA DPAK
- Quantity:
- Payment:
- Shipping:
Inventory:4,040
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Product details
Overview
LF85CDT-TR from STMicroelectronics is a very low-dropout linear voltage regulator with logic-controlled electronic shutdown, delivering 8.5 V output at up to 500 mA. It features 0.45 V dropout at 200 mA, 50 µA quiescent current in OFF mode, and ±2% output voltage accuracy (C grade) over -40 °C to 125 °C - designed for automotive local power domains requiring AEC-Q100 qualification in DPAK package.
For engineers reviewing the LF85CDT-TR datasheet, LF85CDT-TR pinout, LF85CDT-TR application, or LF85CDT-TR equivalent, this device is selected for battery-powered infotainment subsystems, ADAS sensor rails, and engine control module auxiliary supplies where low-noise, high-temp stability, and controlled power gating are critical.
Technical Context
The LF85CDT-TR implements a PNP pass transistor architecture enabling ultra-low dropout and minimal load-dependent regulation shift. Its TTL-compatible inhibit input (Pin 2) enables precise system-level power sequencing without external logic.
Internal thermal and current limiting protect against fault conditions across its full operating range (-40 °C to 125 °C junction), while only 2.2 µF ceramic output capacitance ensures stability - eliminating bulk electrolytics and reducing PCB footprint in space-constrained automotive modules.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 8.5 V ±2% at 25 °C; maintains regulation across -40 °C to 125 °C for automotive ECU rails |
| Dropout Voltage | 0.45 V typical at 200 mA; enables operation with <1 V headroom (e.g., 9.5 V input → 8.5 V out) |
| Quiescent Current | 50 µA in OFF mode; reduces standby power in always-on vehicle networks |
| Output Current | 500 mA continuous; supports multi-rail microcontrollers and CAN transceivers |
| Supply Rejection | 82 dB at 120 Hz; suppresses alternator ripple and switching noise in 12 V systems |
| Stability Capacitor | 2.2 µF ceramic (ESR 0.1–10 Ω); eliminates need for large tantalum or aluminum caps |
| Operating Temp | -40 °C to 125 °C junction; qualified per AEC-Q100 Grade 1 for under-hood use |
Pinout & Package
LF85CDT-TR uses the DPAK (TO-252-3) surface-mount package with exposed thermal pad electrically connected to GND. Pin 1 = Input, Pin 2 = Inhibit (TTL-compatible active-low), Pin 3 = Output, Tab = GND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (IN) | Regulator input supply | Accepts 9.5–16 V DC; internal protection limits VI to 40 V absolute max |
| Pin 2 (INH) | Inhibit control input | Active-low TTL logic: ≤0.8 V = OFF (50 µA IQ), ≥2 V = ON (500 µA IQ) |
| Pin 3 (OUT) | Regulated output | Delivers stable 8.5 V ±2% to load; requires only 2.2 µF ceramic CO |
| Tab (GND) | Power ground & thermal path | Electrically tied to GND; must be soldered to PCB copper pour for thermal dissipation |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 qualified | Grade 1 (-40 °C to 125 °C), including PAT/SYL/SBL statistical testing for automotive reliability |
| Logic-controlled shutdown | TTL-compatible INH pin enables microcontroller-driven power gating of sub-systems |
| Low-noise regulation | 50 µV RMS output noise (10 Hz–100 kHz); suitable for analog sensor and RF circuitry |
| Thermal & current protection | Internally limits power dissipation and output current - no external foldback required |
| Minimal external components | Only two capacitors needed: 0.1 µF input + 2.2 µF output - reduces BOM count and layout area |
Applications
| Infotainment Power Rail | ADAS Camera Module |
|---|---|
|
Use Scenario: Local 8.5 V supply for LCD backlight drivers and audio codecs in head-unit designs. IC Role / Device Role / Timing Role: Primary LDO regulator providing clean, sequenced power to mixed-signal ICs. Use Value: 0.45 V dropout allows direct derivation from 9.5 V battery rail during cold-crank; 50 µA OFF current extends key-off battery life. |
Use Scenario: Dedicated 8.5 V rail for CMOS image sensor biasing and ISP power in surround-view cameras. IC Role / Device Role / Timing Role: Low-noise, thermally robust local regulator with fast enable/disable response. Use Value: 50 µV output noise prevents image artifacts; AEC-Q100 qualification ensures operation at 105 °C ambient under hood. |
| Engine Control Unit (ECU) | Body Control Module (BCM) |
|
Use Scenario: Auxiliary 8.5 V supply for CAN FD transceivers and diagnostic interfaces in gasoline/diesel ECUs. IC Role / Device Role / Timing Role: Fault-tolerant LDO with integrated thermal shutdown and wide-input capability. Use Value: Withstands 40 V load-dump transients (via upstream TVS); 82 dB SVR rejects alternator ripple at 120 Hz. |
Use Scenario: Power source for LIN transceivers and door module MCUs requiring stable 8.5 V under variable battery conditions. IC Role / Device Role / Timing Role: Enable-controlled regulator supporting sleep/wake transitions in low-power gateways. Use Value: 50 µA OFF-mode IQ meets ULP requirements; DPAK package enables automated reflow assembly on dense BCM PCBs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LDL112PU33R | Fixed 3.3 V output; 200 mA max; 170 mV dropout; no inhibit function | Lacks shutdown control and 8.5 V output; unsuitable for 8.5 V rail or power-gated systems | Select only if 3.3 V output and lower current suffice - not a functional replacement |
| TLD1120-12ES | Adjustable output (1.2–12 V); 1.2 A rating; 200 mV dropout; no AEC-Q100 certification | Higher current but unqualified for automotive; requires external feedback resistors and shutdown logic | Use only in industrial non-automotive designs needing adjustable output and higher IOUT |
Compared with LDL112PU33R and TLD1120-12ES, LF85CDT-TR uniquely combines fixed 8.5 V output, AEC-Q100 Grade 1 qualification, TTL inhibit, and 500 mA capability in DPAK - making it the sole drop-in solution for automotive 8.5 V power domains requiring production-grade reliability.
Availability
LF85CDT-TR is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, and engine control units requiring stable component supply with full AEC-Q100 traceability and long-term lifecycle support.
Supply support for LF85CDT-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.
LF85CDT-TR belongs to the LFXX family of very low-dropout regulators engineered specifically for automotive power distribution - emphasizing thermal robustness, low IQ, and AEC-Q100 compliance in compact surface-mount packages.
FAQ
What is the minimum input voltage required for regulation at 500 mA load?
The LF85CDT-TR requires a minimum input voltage of 8.95 V (8.5 V + 0.45 V dropout) to maintain regulation at 500 mA. At 200 mA, dropout is 0.45 V typ.; at 500 mA, it rises to 0.7 V max per automotive-grade specs - so 9.2 V input ensures margin across temperature and process variation.
Can the INH pin be left floating, or does it require a pull-up/down resistor?
The INH pin must not be left floating. It is TTL-compatible and internally biased - but STMicroelectronics specifies a 10 kΩ pull-up to VIN is recommended for default-ON operation. For default-OFF, use a 10 kΩ pull-down to GND. Floating may cause erratic enable behavior due to noise susceptibility.
Is the DPAK thermal pad required to be soldered to PCB ground plane?
Yes. The exposed thermal tab is electrically connected to GND and serves as the primary heat path. STMicroelectronics mandates soldering the tab to ≥200 mm² of 2-oz copper GND plane with ≥4 thermal vias (0.3 mm diameter) to achieve RthJA ≤ 100 °C/W and prevent thermal shutdown above 85 °C ambient.
Does LF85CDT-TR support reverse-polarity input protection?
No. LF85CDT-TR has no internal reverse-voltage protection. If reverse polarity is possible in the application (e.g., battery misconnection), an external series Schottky diode (e.g., STPS2L25U) must be added at the input - adding ~0.3 V forward drop but preventing damage.
LF85CDT-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- 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:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DPAK
LF85CDT-TR FAQ
1.How can I place an order for LF85CDT-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for LF85CDT-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 LF85CDT-TR reliable?
The price and inventory of LF85CDT-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LF85CDT-TR is usually 5 days.
3.What payment methods are accepted for LF85CDT-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LF85CDT-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LF85CDT-TR?
LF85CDT-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LF85CDT-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 LF85CDT-TR?
For technical support, including LF85CDT-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LF85CDT-TR requirements.
6.How does Aetrix verify that LF85CDT-TR is sourced from the original manufacturer or authorized distributors?
All LF85CDT-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 LF85CDT-TR meets industry standards.
7.What is the process for return or replacement of LF85CDT-TR?
All LF85CDT-TR units undergo pre-shipment inspection (PSI). If there is an issue with LF85CDT-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 LF85CDT-TR part is unused and in its original packaging.
Return procedure for LF85CDT-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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