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Texas Instruments LM43603DSUR
- Part No.:
- LM43603DSUR
- Manufacturer:
- Texas Instruments
- Package:
- 16-VFDFN Exposed Pad
- Datasheet:
-
LM43603DSUR.pdf
- Description:
- IC REG BUCK ADJ 3A 16SON
- Quantity:
- Payment:
- Shipping:
Inventory:2,250
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Product details
Overview
LM43603DSUR from Texas Instruments is a 3.5-V to 36-V, 3-A synchronous step-down DC-DC converter in VSON-16 (4.1 mm × 5.1 mm) package. It delivers high efficiency across load range using peak current mode control, features internal compensation, 27-µA quiescent current in regulation, and meets EN55022 Class B radiated EMI limits. Used in industrial power supplies and telecom systems requiring wide-input, compact, and EMI-compliant regulation.
For engineers reviewing the LM43603DSUR datasheet, LM43603DSUR pinout, LM43603DSUR application, or LM43603DSUR equivalent, key selection criteria include input voltage range (3.5–36 V), output current capability (3 A), switching frequency adjustability (200 kHz–2.2 MHz), power-good flag, and soft-start/tracking functionality for system sequencing and reliability.
Technical Context
The LM43603DSUR employs peak current mode control with cycle-by-cycle current limiting and internal slope compensation, enabling stable operation with minimal external components. Its architecture integrates synchronous rectification, internal LDO biasing (VCC and BIAS pins), and precision enable with 200-mV hysteresis for robust UVLO behavior.
It supports frequency synchronization via the SYNC pin (2–5.5 V logic levels, 10–90% duty cycle), adjustable switching frequency via RT resistor (200 kHz–2.2 MHz), and output voltage tracking/soft-start via SS/TRK pin with 1.25–2.75 µA charge current and 4.1 ms default ramp time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5 V to 36 V - supports wide-input industrial and automotive sub-AM band applications without pre-regulation. |
| Output Current | 3 A continuous - sufficient for point-of-load regulation of FPGAs, DSPs, and microcontrollers. |
| Quiescent Current | 27 µA in regulation - enables battery-backed or always-on systems with low standby power loss. |
| Switching Frequency | 200 kHz to 2.2 MHz (500 kHz default) - allows optimization of size (higher fSW → smaller inductor/capacitors) and efficiency (lower fSW → reduced switching loss). |
| Feedback Reference | 1.011 V ±1.2% over –40°C to +125°C - ensures precise output voltage setting with <±1% error at 3.3 V or 5 V outputs. |
| EMI Compliance | Meets EN55022/CISPR 22 Class B radiated emissions - reduces need for external filtering in commercial-grade equipment. |
| Thermal Shutdown | 160°C shutdown / 150°C recovery - protects against sustained overload or poor heatsinking in enclosed environments. |
Pinout & Package
VSON-16 package (4.10 mm × 5.10 mm, wettable flanks), 0.5-mm pitch, thermally enhanced bottom-exposed pad connected internally to AGND. Designed for high-density PCB layouts with low thermal resistance (RθJB = 9.6°C/W on 4-layer JEDEC board).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1,2,3) | Switch node | Connects to inductor; carries high di/dt switching current - requires short, low-inductance trace to minimize EMI and voltage spikes. |
| CBOOT (4) | Bootstrap capacitor connection | Supplies gate drive for high-side MOSFET; requires 470-nF ceramic capacitor between CBOOT and SW for reliable bootstrapping. |
| VCC (5) | Internal LDO output | Bypass with 1–10 µF capacitor to AGND; no external loading permitted - powers internal circuitry and gate drivers. |
| BIAS (6) | Optional LDO input | Tie to VOUT (if 3.3–28 V) or external rail to improve light-load efficiency; bypass with 1–10 µF capacitor when used. |
| SYNC (7) | External clock input | Accepts 2–5.5 V square wave; enables synchronization to system clock or noise-sensitive frequency bands - ground if unused. |
| RT (8) | Frequency programming | Resistor to AGND sets fSW; open-circuit yields 500 kHz default - tolerance impacts accuracy by ±10%. |
| PGOOD (9) | Open-drain power-good flag | Asserts high when VOUT is within ±12% of target (77–113% of FB voltage); requires 10–100 kΩ pull-up to ≤12 V logic rail. |
| FB (10) | Feedback sense input | Monitors resistive divider output; 1.011 V reference enables precise VOUT setting - leakage <65 nA minimizes divider error. |
| SS/TRK (11) | Soft-start / tracking control | Capacitor extends soft-start time; external ramp enables output voltage tracking during power-up sequencing. |
| EN (12) | Enable input | Logic-level control (2.2 V threshold, 200-mV hysteresis); connects directly to VIN or resistor divider for programmable UVLO. |
| VIN (13,14) | Main input supply | Connects to bulk input capacitors; dual pins reduce IR drop and improve thermal performance under 3-A load. |
| PGND (15,16) | Power ground | Low-impedance return path for high-side/low-side MOSFETs and input/output capacitors - must tie to PCB ground plane and PAD. |
| PAD | Exposed thermal pad | Internally connected to AGND; primary heat dissipation path - requires solid copper fill and multiple vias to inner ground layers. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous rectification | Eliminates external Schottky diode - reduces conduction loss and improves full-load efficiency by up to 5% vs. asynchronous designs. |
| Internal compensation | Reduces external component count to only input/output capacitors, inductor, feedback divider, and optional RT/SS capacitors - accelerates design and layout. |
| Stable with diverse output capacitors | Supports ceramic, polymer, tantalum, and aluminum electrolytic types - simplifies BOM management and enables cost-optimized output filtering. |
| Pre-biased soft-start | Allows safe startup into pre-charged output rails - prevents reverse current flow and protects downstream loads during hot-swap or multi-rail sequencing. |
| Output short-circuit protection with hiccup mode | Enters 5.5-ms retry delay after 32-cycle fault detection - limits average power dissipation during sustained shorts and avoids thermal runaway. |
Applications
| Industrial Power Supplies | Telecommunications Systems |
|---|---|
Use Scenario: Distributed 24-V or 48-V DC distribution powering field I/O modules, PLCs, and sensors. IC Role / Device Role / Timing Role: Primary buck regulator converting 24 V to 3.3 V/5 V for microcontrollers and communication interfaces. Use Value: Wide 3.5–36 V input accommodates brownout and surge conditions; 27-µA IQ extends uptime in battery-buffered backup systems. | Use Scenario: Intermediate bus conversion in base station radios and optical line terminals with strict EMI requirements. IC Role / Device Role / Timing Role: Point-of-load regulator delivering 3.3 V at 3 A to FPGA transceivers and SerDes blocks. Use Value: EN55022 Class B compliance eliminates need for external EMI filters; SYNC pin enables spread-spectrum alignment with system clocks. |
| Sub-AM Band Automotive | High Efficiency Point-Of-Load Regulation |
Use Scenario: Infotainment head units and ADAS camera modules operating from 12-V battery with cold-crank (4.5 V) and load-dump (42 V) transients. IC Role / Device Role / Timing Role: Main 5-V or 3.3-V supply for SoCs and image signal processors. Use Value: 42-V absolute max input withstands load dump; BIAS pin tied to VOUT improves light-load efficiency critical for standby modes. | Use Scenario: Compact embedded systems such as medical handhelds and portable test equipment requiring regulated 3.3 V from single-cell Li-ion or USB PD sources. IC Role / Device Role / Timing Role: High-efficiency buck converter minimizing thermal footprint in space-constrained enclosures. Use Value: VSON-16 wettable flanks enable automated optical inspection (AOI); RθJB = 9.6°C/W supports >2 W dissipation without heatsink. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM43602DSQR | 2-A rated, identical VSON-16 pinout and feature set; lower current limit (4.2 A peak vs. 5.5 A) and higher RDS(on) (HS: 140 mΩ, LS: 75 mΩ). | Suitable for <2-A loads where thermal margin or cost reduction is prioritized over headroom. | Select when 2 A output suffices and board layout reuse is required - same footprint and control interface. |
| TPS54360BDDAR | 3-A, 3.5–60-V input, SOIC-8 package; no BIAS pin, no SYNC, higher IQ (57 µA), no PGOOD, requires external compensation. | Better for ultra-wide VIN (up to 60 V) but lacks EMI optimization and advanced sequencing features. | Choose for cost-sensitive, non-EMI-critical designs needing extended input range - not pin-compatible; requires layout change. |
Compared with LM43602DSQR, LM43603DSUR provides 50% higher current headroom and lower conduction loss; versus TPS54360BDDAR, it offers superior EMI performance, integrated compensation, and sequencing support - making it optimal for compact, high-reliability, and noise-sensitive applications.
Availability
LM43603DSUR is available at Aetrix Electronics and suitable for industrial power supplies, telecommunications systems, and sub-AM band automotive electronics requiring stable component supply, long-term lifecycle support, and consistent parametric performance.
Supply support for LM43603DSUR 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 ICs, with decades of expertise in high-reliability DC-DC conversion.
The LM4360x family was designed for wide-input, high-efficiency synchronous buck regulation in space-constrained industrial and automotive systems - emphasizing EMI control, thermal robustness, and ease of use through internal compensation and flexible sequencing.
FAQ
What is the maximum input voltage rating for the LM43603DSUR?
The LM43603DSUR has an absolute maximum input voltage rating of 42 V across VIN to PGND, with recommended operating range from 3.5 V to 36 V. This 42-V rating enables reliable operation during automotive load-dump events and industrial transient surges, provided proper input capacitance and layout practices are followed per TI's Layout Guidelines section.
Does the LM43603DSUR require external compensation components?
No, the LM43603DSUR features internal compensation, eliminating the need for external Type-II or Type-III compensation networks. This simplifies design, reduces bill-of-materials count, and improves stability across varying output capacitor ESR and capacitance values - including ceramic, polymer, and electrolytic types - as confirmed in the "Stable with Almost Any Combination" feature statement.
How does the BIAS pin improve efficiency in the LM43603DSUR?
The BIAS pin allows the LM43603DSUR to power its internal LDO from the output rail (when 3.3 V ≤ VOUT ≤ 28 V) instead of VIN, reducing power loss in the bias supply path. When configured this way, the device achieves higher light-load efficiency - particularly beneficial in battery-powered or always-on systems where quiescent current dominates total consumption.
Can the LM43603DSUR be synchronized to an external clock source?
Yes, the LM43603DSUR supports frequency synchronization via its SYNC pin, which accepts a 2–5.5 V square-wave clock with 10–90% duty cycle and minimum pulse width of 80 ns. This enables noise-sensitive system designs to align switching edges with quiet periods or avoid critical frequency bands - a capability not present in many competing 3-A buck regulators.
What thermal performance can be expected from the LM43603DSUR in VSON-16 package?
In the VSON-16 package, the LM43603DSUR achieves a junction-to-board thermal resistance (RθJB) of 9.6°C/W on a standard 4-layer JEDEC board. With proper PCB layout - including a fully soldered exposed thermal pad connected to inner ground planes via ≥6 thermal vias - it sustains 3-A continuous output at ambient temperatures up to 85°C without forced airflow.
LM43603DSUR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 16-VFDFN Exposed Pad
- 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):
- 3.5V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1V
- Voltage - Output (Max):
- 28V
- Current - Output:
- 3A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 16-SON (4x5)
LM43603DSUR FAQ
1.How can I place an order for LM43603DSUR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM43603DSUR 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 LM43603DSUR reliable?
The price and inventory of LM43603DSUR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM43603DSUR is usually 5 days.
3.What payment methods are accepted for LM43603DSUR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM43603DSUR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM43603DSUR?
LM43603DSUR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM43603DSUR 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 LM43603DSUR?
For technical support, including LM43603DSUR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM43603DSUR requirements.
6.How does Aetrix verify that LM43603DSUR is sourced from the original manufacturer or authorized distributors?
All LM43603DSUR 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 LM43603DSUR meets industry standards.
7.What is the process for return or replacement of LM43603DSUR?
All LM43603DSUR units undergo pre-shipment inspection (PSI). If there is an issue with LM43603DSUR, 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 LM43603DSUR part is unused and in its original packaging.
Return procedure for LM43603DSUR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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