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Texas Instruments LMR36503RFRPER
- Part No.:
- LMR36503RFRPER
- Manufacturer:
- Texas Instruments
- Package:
- 9-PowerVFQFN
- Datasheet:
-
LMR36503RFRPER.pdf
- Description:
- IC REG BUCK ADJ 300MA 9VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,101
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Product details
Overview
LMR36503RFRPER from Texas Instruments is a 3-V to 65-V, 0.3-A synchronous buck DC/DC converter in a 2-mm × 2-mm HotRod™ VQFN-HR (RPE) package with wettable flanks. It features adjustable output voltage via FB pin, FPWM light-load operation, 4 µA no-load IQ at 24 VIN→3.3 VOUT, and 200 kHz–2.2 MHz programmable switching frequency using the RT pin. It serves as a rugged front-end power supply for industrial sensors and transmitters.
For engineers reviewing the LMR36503RFRPER datasheet, LMR36503RFRPER pinout, LMR36503RFRPER application, or LMR36503RFRPER equivalent, key selection considerations include its ultra-low quiescent current, 70-V input transient tolerance, internal compensation, precision enable/UVLO, and PGOOD flag with glitch filtering - all critical for reliable operation in factory automation and building control systems.
Technical Context
The LMR36503RFRPER uses peak current mode control with internal compensation, enabling stable regulation with minimal external output capacitance. Its FPWM light-load mode ensures consistent switching frequency under varying loads, eliminating audible noise and simplifying EMI filtering.
It integrates high- and low-side MOSFETs (RDS(on) = 560 mΩ / 280 mΩ), a precision 1.0 V reference (±1%), and thermal shutdown (168°C trip). The RT pin supports resistor-based frequency programming, while EN/UVLO provides precise start-up control (1.263 V threshold, 0.35 V hysteresis) and direct VIN connection capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.0 V (falling) to 65 V - supports wide industrial rails and withstands 70-V transients without external protection. |
| Output Current | 0.3 A continuous - sufficient for powering microcontrollers, analog sensors, and signal chains in space-constrained modules. |
| Quiescent Current | 4 µA at 24 VIN → 3.3 VOUT - enables multi-year battery life in always-on industrial monitoring nodes. |
| Switching Frequency | 200 kHz to 2.2 MHz (RT-programmable) - allows optimization for efficiency (low fSW) or size (high fSW) and avoids AM band interference. |
| Output Voltage | Adjustable via FB pin (0.985–1.01 V reference) - supports custom rail generation (e.g., 3.3 V, 5 V, 12 V) with ±1.5% accuracy over full load/temperature. |
| Package | VQFN-HR (RPE), 9-pin, 2.0 mm × 2.0 mm with wettable flanks - enables automated optical inspection and robust solder joint reliability in harsh environments. |
| Operating Junction Temp | –40°C to +150°C - rated for under-hood, motor drive, and factory-floor deployments without derating. |
Pinout & Package
VQFN-HR (RPE) 9-pin, 2.0 mm × 2.0 mm package with wettable flanks and corner anchor pads for enhanced solder joint reliability and AOI compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - RT | Frequency programming input | Connect resistor to GND to set fSW from 200 kHz to 2.2 MHz; floating disables switching - enables layout flexibility and EMI tuning. |
| 2 - PGOOD | Open-drain power-good flag | Asserts high after soft-start and valid output; includes 25-µs glitch filter and 1.95-ms delay - replaces external supervisor IC in system sequencing. |
| 3 - EN/UVLO | Enable and input UVLO input | 1.263 V turn-on threshold with 0.35 V hysteresis; supports direct VIN tie - enables simple, robust power sequencing and brownout protection. |
| 4 - VIN | Main input power supply | Accepts 3–65 V; handles 70-V transients - eliminates need for upstream TVS or overvoltage clamping in surge-prone environments. |
| 5 - SW | Power switch node | Connects to external inductor; drives internal high-side MOSFET - requires short, low-inductance routing to minimize EMI and ringing. |
| 6 - BOOT | Bootstrap capacitor connection | Connects 100-nF capacitor to SW - sustains gate drive for high-side FET during duty cycles up to 98%. |
| 7 - VCC | Internal LDO output | 3.15 V ±25 mV supply for control circuitry; 240 mA current limit - powers internal logic and can bias PGOOD pull-up. |
| 8 - FB | Feedback input (adjustable variant) | Connects to resistor divider; senses 1.0 V reference - enables precise output voltage setting independent of load or line variation. |
| 9 - GND | Power ground | Common return for VIN, SW, and control circuits - must be connected to CIN with short, wide traces to minimize noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low IQ (4 µA) | Enables >10-year battery life in wireless field transmitters operating at 24 V input and 3.3 V/100 µA system load. |
| 70-V input transient tolerance | Meets IEC 61000-4-5 surge immunity requirements without external protection components, reducing BOM cost and board area. |
| Internal compensation | Eliminates external Type-II/III compensation network - reduces design cycle time and component count while maintaining stability across 0–0.3 A load. |
| FPWM light-load operation | Prevents frequency shifting and associated EMI peaks during partial-load conditions - simplifies compliance testing in EMC-sensitive applications. |
| PGOOD with delayed release | Provides glitch-filtered, timing-controlled system status indication - removes need for discrete reset supervisor IC and associated RC timing network. |
Applications
| Factory Automation Sensors | Building HVAC Controllers |
|---|---|
|
Use Scenario: Powering 4–20 mA loop-powered temperature/pressure transmitters in industrial plants with 24 V DC rails subject to load dump and lightning-induced surges. IC Role / Device Role / Timing Role: Primary step-down regulator converting 24–36 V plant supply to stable 3.3 V for MCU, ADC, and analog front-end - operates continuously with <4 µA standby draw. Use Value: Eliminates external surge protection and linear regulators, shrinking footprint by >40% while meeting IEC 61000-4-5 Level 3 immunity. |
Use Scenario: Supplying 5 V to microcontroller, display, and relay drivers in wall-mounted HVAC thermostats powered from 24 VAC-derived DC. IC Role / Device Role / Timing Role: Compact, efficient buck converter delivering 0.3 A with FPWM mode to avoid audible coil whine during variable-speed fan control. Use Value: Enables silent operation and extended battery backup runtime during AC loss, with integrated PGOOD replacing discrete reset IC. |
| Garden Power Tool Control | Fire Safety Smoke Detectors |
|
Use Scenario: Regulating battery-pack voltage (18–60 V) to 3.3 V for motor driver logic and communication ICs in cordless drills and trimmers. IC Role / Device Role / Timing Role: High-input-voltage buck converter with 150°C junction rating - survives motor stall currents and ambient temperatures >85°C inside tool housings. Use Value: Replaces discrete buck+LDO solutions, reducing thermal stress and enabling smaller, lighter tool designs without compromising runtime. |
Use Scenario: Providing regulated 3.3 V from lithium primary cell (2.0–3.6 V) or 9 V alkaline battery in standalone smoke alarms with 10-year shelf life. IC Role / Device Role / Timing Role: Ultra-low-IQ buck converter supporting wide VIN range and precise enable threshold - extends battery life while ensuring reliable wake-up on alarm trigger. Use Value: Achieves >10-year shelf life with <6.5 µA total system quiescent current, meeting UL 217 and EN 14604 longevity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMR36503R5RPER | Fixed 5-V output; same RPE package, wettable flanks, and FPWM mode; identical IQ and thermal specs. | Used where 5 V rail is standard (e.g., USB peripherals, legacy sensors); eliminates feedback resistors but lacks output flexibility. | Select when fixed 5 V simplifies design and reduces component count - no change to PCB layout required. |
| LMR36506RFRPER | Same architecture and pinout, but 0.6-A output current, higher RDS(on) (HS: 320 mΩ, LS: 160 mΩ), and identical 3–65 V input range. | Suitable for higher-current loads (e.g., multi-sensor nodes, motor gate drivers); shares layout but requires inductor/capacitor re-rating. | Choose when future-proofing for >0.3 A loads or consolidating BOM across 0.3-A/0.6-A variants - pin-compatible upgrade path. |
Compared with LMR36503R5RPER, the LMR36503RFRPER offers output voltage flexibility at the cost of two external resistors; compared with LMR36506RFRPER, it delivers lower conduction loss at 0.3-A loads but cannot scale to 0.6 A without redesign.
Availability
LMR36503RFRPER is available at Aetrix Electronics and suitable for factory automation sensors, building HVAC controllers, and garden power tool control requiring stable component supply, long-term manufacturability, and automotive-grade reliability.
Supply support for LMR36503RFRPER 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 technologies, with decades of industrial-grade product development and manufacturing excellence.
The LMR36503RFRPER belongs to TI's LMR365xx family of ultra-small, high-voltage buck converters designed specifically for rugged industrial power supplies - emphasizing ultra-low IQ, transient robustness, and minimal solution size in harsh environments.
FAQ
What is the minimum input voltage required for LMR36503RFRPER to start switching?
The LMR36503RFRPER has a falling-threshold minimum operating input voltage of 2.45 V (typical) and a rising-threshold of 3.4 V (typical). Once started, it sustains regulation down to 2.45 V; startup requires ≥3.4 V at VIN. This behavior is defined by the internal EN/UVLO circuit and ensures reliable operation across wide input transients.
Does LMR36503RFRPER support synchronization to an external clock?
No, LMR36503RFRPER does not support external clock synchronization. It is an RT-pin variant that enables resistor-programmed free-running frequency from 200 kHz to 2.2 MHz. Synchronization capability is reserved for MODE/SYNC variants (e.g., LMR36503RFRPJR), which are distinct orderable part numbers.
How is the output voltage set on LMR36503RFRPER?
The LMR36503RFRPER uses the FB pin to sense a resistor divider connected between VOUT and GND. With an internal 1.0 V reference (±1%), the output voltage is calculated as VOUT = 1.0 V × (1 + RFBT/RFBB). Standard configurations include 3.3 V (RFBT = 205 kΩ, RFBB = 100 kΩ) and 5.0 V (RFBT = 402 kΩ, RFBB = 100 kΩ).
What thermal performance can be expected from LMR36503RFRPER in a typical 4-layer PCB layout?
In a JEDEC-standard 4-layer PCB layout, the LMR36503RFRPER exhibits a junction-to-ambient thermal resistance (RθJA) of 84.4°C/W. At 0.3 A load and 24 V input, typical power dissipation is ~180 mW, resulting in ~15°C junction rise above ambient - well within its –40°C to +150°C operating range.
Is LMR36503RFRPER compatible with lead-free reflow profiles?
Yes, LMR36503RFRPER is qualified for standard IPC/JEDEC J-STD-020 lead-free reflow profiles, including peak temperatures up to 260°C. Its VQFN-HR (RPE) package with wettable flanks supports automated optical inspection of solder joints post-reflow, ensuring process reliability in high-volume manufacturing.
LMR36503RFRPER Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 9-PowerVFQFN
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 65V
- Voltage - Output (Min/Fixed):
- 1V
- Voltage - Output (Max):
- 65V
- Current - Output:
- 300mA
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 9-VQFN-HR (2x2)
LMR36503RFRPER FAQ
1.How can I place an order for LMR36503RFRPER through Aetrix?
Please submit a Request for Quotation (RFQ) for LMR36503RFRPER 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 LMR36503RFRPER reliable?
The price and inventory of LMR36503RFRPER are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMR36503RFRPER is usually 5 days.
3.What payment methods are accepted for LMR36503RFRPER?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMR36503RFRPER transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMR36503RFRPER?
LMR36503RFRPER orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMR36503RFRPER 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 LMR36503RFRPER?
For technical support, including LMR36503RFRPER datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMR36503RFRPER requirements.
6.How does Aetrix verify that LMR36503RFRPER is sourced from the original manufacturer or authorized distributors?
All LMR36503RFRPER 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 LMR36503RFRPER meets industry standards.
7.What is the process for return or replacement of LMR36503RFRPER?
All LMR36503RFRPER units undergo pre-shipment inspection (PSI). If there is an issue with LMR36503RFRPER, 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 LMR36503RFRPER part is unused and in its original packaging.
Return procedure for LMR36503RFRPER:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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