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Texas Instruments LM53635AQRNLTQ1
- Part No.:
- LM53635AQRNLTQ1
- Manufacturer:
- Texas Instruments
- Package:
- 22-PowerVFQFN
- Datasheet:
-
LM53635AQRNLTQ1.pdf
- Description:
- IC REG BUCK ADJ 3.5A 22VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,256
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Product details
Overview
LM53635AQRNLTQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive synchronous buck DC-DC converter delivering up to 3.5 A at 3.3 V, 5 V, or adjustable output, operating from 3.55 V to 36 V input with 2.1-MHz fixed switching frequency and ±1% output voltage accuracy over –40°C to +125°C junction temperature. It integrates high-side/low-side MOSFETs, internal compensation, soft-start, thermal shutdown, and a filtered open-drain RESET output - used in instrument clusters and telematics power rails.
For engineers reviewing the LM53635AQRNLTQ1 datasheet, LM53635AQRNLTQ1 pinout, LM53635AQRNLTQ1 application, or LM53635AQRNLTQ1 equivalent, key selection considerations include its 3.5-A continuous output capability, wettable-flank VQFN-22 package for automotive solder-joint inspection, spread-spectrum EMI reduction, external frequency synchronization support, and 15-µA no-load quiescent current in light-load mode.
Technical Context
The LM53635AQRNLTQ1 employs peak-current-mode control with adaptive minimum on/off time (65 ns / 60 ns) to sustain 2.1-MHz operation across wide VIN–VOUT ratios - enabling regulation of 3.3 V from as low as 3.55 V input. Its architecture supports seamless PWM-to-PFM transition and includes built-in zero-cross current limiting and hiccup-mode short-circuit protection with 6-ms wait time.
This device uses flip-chip HotRod QFN packaging with wettable flanks to minimize parasitic inductance, reduce switch-node ringing, and lower radiated EMI. The integrated 3.1-V LDO (VCC), BIAS pin for auxiliary biasing, and programmable FPWM pin enable flexible system-level power sequencing and noise-sensitive timing-critical applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 3.5 A continuous - supports high-power automotive subsystems without external current boosting. |
| Input Voltage Range | 3.55 V to 36 V - enables direct battery connection (12 V/24 V systems) with 42-V transient tolerance ≤500 ms. |
| Switching Frequency | 2.1 MHz nominal - allows use of compact 1–2.2 µH inductors and avoids AM-band interference. |
| Quiescent Current | 15 µA typical at no load (3.3 V out) - eliminates need for backup LDO in always-on vehicle modules. |
| Output Accuracy | ±1% over –40°C to +125°C TJ - ensures stable microcontroller/core logic supply under full automotive ambient range. |
| RESET Output | Open-drain with 3-ms release timer and internal glitch filter (12–45 µs) - replaces discrete supervisor IC in safety-critical domains. |
| Package | VQFN-HR (RNL), 5.0 mm × 4.0 mm, 22-pin, wettable flanks - supports automated optical solder-joint inspection per AEC-Q200. |
Pinout & Package
VQFN-HR (RNL) 22-pin package with exposed thermal pad, 0.6-mm pin pitch, wettable flanks, and 5.0 mm × 4.0 mm body size - optimized for low-inductance layout and automotive thermal reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Internal 3.1-V LDO output | Supplies internal control circuitry; requires 4.7-µF capacitor to AGND for stability. |
| CBOOT | Bootstrap capacitor node | Connects 470-nF capacitor to SW to drive high-side MOSFET gate above VIN. |
| SYNC | External clock input | Accepts 1.9–2.3 MHz system clock (rising-edge triggered); enables multi-rail synchronization. |
| PVIN1 / PVIN2 | Main power inputs | Dual high-current VIN pins - must be shorted on PCB to minimize loop inductance. |
| SW | Switch node | Connects directly to power inductor; critical for EMI performance and thermal management. |
| PGND1 / PGND2 | Power ground terminals | Eight dedicated GND pins - must be tied together and connected to AGND/system ground. |
| FB | Feedback input | For adjustable version: connects to resistor divider; for fixed versions: tied to output. |
| BIAS | Auxiliary bias input | Connected to output rail to improve efficiency and reduce dropout at light loads. |
| FPWM | Forced PWM mode control | High = fixed 2.1-MHz operation; low = automatic PFM/PWM transition for ultra-low IQ. |
| EN | Enable input | Active-high logic; threshold 1.7–2.0 V; hysteresis 0.45–0.55 V prevents chatter during brownout. |
| RESET | Open-drain fault flag | Asserts low on UVLO, thermal shutdown, or EN deactivation; includes 3-ms release delay. |
| AGND | Analog reference ground | Reference point for FB, BIAS, and internal error amplifier; must be star-connected to PGND. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Grade 1 qualification | Validated for –40°C to +125°C ambient operation with HBM ±2.5 kV and CDM ±1 kV ESD robustness. |
| Integrated hot-plug protection | UVLO start-up threshold of 3.2–3.55 V rising with 0.28–0.4 V hysteresis prevents erratic startup during cold cranking. |
| Low EMI HotRod packaging | Flip-chip construction reduces switch-node loop inductance by >50%, minimizing radiated emissions and dV/dt-induced noise. |
| Spread-spectrum modulation | ±3% frequency dithering centered at 2.1 MHz lowers peak EMI by up to 10 dB without affecting regulation. |
| Thermal robustness | Junction-to-board thermal resistance of 5.4°C/W enables 3.5-A operation at 105°C ambient with standard 2-layer PCB. |
Applications
| Instrument Cluster Power Supply | Telematics Head Unit Core Rail |
|---|---|
Use Scenario: Supplies 3.3 V to MCU, display controller, and CAN transceivers in digital instrument clusters with strict EMI limits and cold-crank resilience. IC Role / Device Role / Timing Role: Primary 3.5-A synchronous buck regulator providing clean, regulated core voltage with RESET supervision. Use Value: 15-µA quiescent current extends battery life in key-off monitoring; 3.55-V minimum input ensures operation during 6-V cranking dips. |
Use Scenario: Powers application processor and memory subsystem in automotive infotainment head units requiring low-noise, high-efficiency conversion from 12-V battery. IC Role / Device Role / Timing Role: High-frequency (2.1 MHz) step-down regulator with SYNC input for synchronized multi-rail power sequencing. Use Value: Spread-spectrum mode reduces conducted EMI peaks below CISPR 25 Class 5 limits; wettable flanks enable AOI verification for zero-defect manufacturing. |
| ADAS Camera Module Bias Rail | Body Control Module Always-On Supply |
Use Scenario: Generates stable 5 V for image sensor and ISP in rear-view or surround-view camera modules exposed to engine bay temperatures. IC Role / Device Role / Timing Role: Fixed 5-V output buck converter with thermal shutdown and 150°C max junction rating for under-hood deployment. Use Value: ±1% output accuracy maintains sensor ADC reference stability; 0.6-V dropout at 3.5 A ensures regulation during battery sag. |
Use Scenario: Provides always-on 3.3 V rail for real-time clock, CAN wake-up logic, and door module microcontrollers in BCMs. IC Role / Device Role / Timing Role: Ultra-low-IQ buck regulator with FPWM disable option to maintain deterministic timing during sleep/wake transitions. Use Value: 2-µA shutdown current minimizes parasitic drain; RESET output signals valid power to host MCU before firmware initialization. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM536353QRNLTQ1 | Fixed 3.3-V output; identical package, pinout, and specs except FB pin internally tied to output divider. | No external feedback resistors required; simplifies layout but lacks output voltage flexibility. | Select when 3.3 V is fixed and board space is constrained - eliminates two resistors and associated routing. |
| LM536355QRNLTQ1 | Fixed 5-V output; same thermal and electrical specs, but internal feedback network set for 5 V. | Optimized for 5-V logic rails (USB PHY, Ethernet PHY, etc.) without external resistor network. | Choose for 5-V applications where precision and simplicity outweigh adjustability needs. |
Compared with LM53635AQRNLTQ1, the fixed-output variants eliminate external feedback components and reduce BOM count, while retaining identical AEC-Q100 qualification, thermal performance, and EMI behavior - making them drop-in alternatives only when output voltage is fixed and design flexibility is not required.
Availability
LM53635AQRNLTQ1 is available at Aetrix Electronics and suitable for automotive instrument clusters, telematics head units, and ADAS camera modules requiring stable component supply, long-term lifecycle assurance, and AEC-Q100-compliant sourcing.
Supply support for LM53635AQRNLTQ1 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 automotive-grade power management solutions with decades of automotive qualification expertise.
The LM536xx-Q1 product line delivers high-efficiency, low-EMI DC-DC converters engineered specifically for automotive infotainment, ADAS, and body electronics - emphasizing AEC-Q100 compliance, thermal resilience, and manufacturability in harsh environments.
FAQ
What is the minimum input voltage required for LM53635AQRNLTQ1 to start switching?
The LM53635AQRNLTQ1 has a rising UVLO threshold of 3.2–3.55 V, meaning it begins switching once input voltage crosses ~3.2 V. This enables reliable operation during automotive cold-crank events down to 6 V battery voltage. The hysteresis (0.28–0.4 V) prevents oscillation near the threshold. For full functionality at 3.5-A load, minimum input is 3.9 V when regulating 3.3 V - verified in Section 7.6 of the datasheet. LM53635AQRNLTQ1 maintains regulation even as VIN approaches VOUT due to adaptive frequency spreading.
Does LM53635AQRNLTQ1 support external frequency synchronization, and what is the acceptable sync range?
Yes, LM53635AQRNLTQ1 supports external synchronization via the SYNC pin, accepting a 1.9–2.3 MHz square wave (rising-edge triggered) with 25–75% duty cycle. This allows precise timing alignment across multiple rails in complex automotive ECUs. The internal oscillator remains active as backup if SYNC is lost. LM53635AQRNLTQ1's sync capability is explicitly confirmed in Table 6-1 and Section 7.5 (FSYNC parameter), and is independent of spread-spectrum mode.
How does the RESET output of LM53635AQRNLTQ1 behave during startup and fault conditions?
The LM53635AQRNLTQ1 RESET pin is an open-drain output that goes low during EN deactivation, input UVLO, thermal shutdown, or output overvoltage. It features a built-in 3-ms release timer after fault clearance and a 12–45 µs glitch filter to reject noise. RESET asserts high only after output reaches 96–110% of target voltage and remains stable - ensuring reliable power-good signaling to host MCUs. This behavior is fully documented in Section 7.5 (VRESET thresholds) and Figure 7-7.
Can LM53635AQRNLTQ1 operate in forced PWM mode, and how is it enabled?
Yes, LM53635AQRNLTQ1 supports forced PWM mode via the FPWM pin: driving FPWM high (≥1.5 V) disables diode emulation and maintains constant 2.1-MHz switching regardless of load - essential for noise-sensitive applications like audio or RF subsystems. The transition time between AUTO and FPWM modes is <100 µs. FPWM must never be left floating; tie to VIN or ground through appropriate pull-up/down. This function is specified in Section 7.5 (VFPWM thresholds) and Section 8.4.
What thermal performance can be expected from LM53635AQRNLTQ1 on a standard 2-layer PCB?
On a standard 2-layer PCB with 1 oz copper and recommended layout (including thermal pad soldered to 400 mm² copper pour), LM53635AQRNLTQ1 achieves a junction-to-board thermal resistance (RθJB) of 5.4°C/W. At 3.5-A load and 13.5-V input, power dissipation is ~0.8 W - resulting in ~4.3°C rise above board temperature. This enables full-rated operation at 105°C ambient, validated per AEC-Q100 lifetime requirements. Thermal data is provided in Section 7.4 and Figure 11-2 of the datasheet.
LM53635AQRNLTQ1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 22-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):
- 3.9V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- 10V
- Current - Output:
- 3.5A
- Frequency - Switching:
- 2.1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 22-VQFN-HR (5x4)
LM53635AQRNLTQ1 FAQ
1.How can I place an order for LM53635AQRNLTQ1 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM53635AQRNLTQ1 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 LM53635AQRNLTQ1 reliable?
The price and inventory of LM53635AQRNLTQ1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM53635AQRNLTQ1 is usually 5 days.
3.What payment methods are accepted for LM53635AQRNLTQ1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM53635AQRNLTQ1 transactions.
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4.How is shipping managed for LM53635AQRNLTQ1?
LM53635AQRNLTQ1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM53635AQRNLTQ1 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 LM53635AQRNLTQ1?
For technical support, including LM53635AQRNLTQ1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM53635AQRNLTQ1 requirements.
6.How does Aetrix verify that LM53635AQRNLTQ1 is sourced from the original manufacturer or authorized distributors?
All LM53635AQRNLTQ1 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 LM53635AQRNLTQ1 meets industry standards.
7.What is the process for return or replacement of LM53635AQRNLTQ1?
All LM53635AQRNLTQ1 units undergo pre-shipment inspection (PSI). If there is an issue with LM53635AQRNLTQ1, 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 LM53635AQRNLTQ1 part is unused and in its original packaging.
Return procedure for LM53635AQRNLTQ1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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