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Texas Instruments LM43603DSUT
- Part No.:
- LM43603DSUT
- Manufacturer:
- Texas Instruments
- Package:
- 16-VFDFN Exposed Pad
- Datasheet:
-
LM43603DSUT.pdf
- Description:
- IC REG BUCK ADJ 3A 16SON
- Quantity:
- Payment:
- Shipping:
Inventory:480
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Product details
Overview
LM43603DSUT from Texas Instruments is a 3.5-V to 36-V, 3-A synchronous step-down DC-DC converter in a 16-pin VSON package (4.1 mm × 5.1 mm). It delivers 27-µA quiescent current in regulation, supports adjustable switching frequency from 200 kHz to 2.2 MHz, and integrates synchronous rectification for high efficiency across load ranges - used in industrial power supplies and automotive sub-AM band systems.
For engineers reviewing the LM43603DSUT datasheet, LM43603DSUT pinout, LM43603DSUT application, or LM43603DSUT equivalent, key selection criteria include its EN precision UVLO threshold (2.2 V typ), internal soft-start (4.1 ms), PGOOD flag with 6% hysteresis, and EMI-compliant operation meeting EN55022 Class B standards.
Technical Context
The LM43603DSUT employs peak current mode control for stable loop compensation and cycle-by-cycle current limiting. Its integrated synchronous FETs feature RDS(on) of 120 mΩ (HS) and 65 mΩ (LS) at IOUT = 1 A and VBIAS = VOUT = 3.3 V, enabling high efficiency even at light loads via DCM/PPM modes.
It supports external frequency synchronization (SYNC pin), output voltage tracking (SS/TRK), and bias supply flexibility via BIAS pin - configurable for tie-to-VOUT (3.3–28 V) or external 3.3/5 V rail. Thermal shutdown activates at 160°C with 10°C hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5 V to 36 V - supports wide-input industrial and automotive rails; absolute max 42 V. |
| Output Current | Up to 3 A continuous - enables single-chip point-of-load conversion for FPGA, DSP, or MCU core supplies. |
| Quiescent Current | 27 µA in regulation - extends battery life in always-on systems without compromising startup capability. |
| Switching Frequency | 200 kHz to 2.2 MHz adjustable - allows optimization of size (high-freq) vs. efficiency (low-freq) and EMI filtering. |
| Feedback Reference | 1.011 V ±1.2% over -40°C to +125°C - ensures tight output regulation across temperature and line/load conditions. |
| Power-Good Flag | Open-drain PGOOD with 77–113% FB threshold window and 6% hysteresis - provides reliable system sequencing and fault detection. |
| Thermal Shutdown | 160°C trip / 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, exposed thermal pad connected internally to AGND - requires PCB thermal vias to ground plane for optimal thermal performance (RθJB = 9.6°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1,2,3) | Switch node | Connects to both internal MOSFETs and external inductor; high dv/dt node requiring minimized trace area and proximity to PGND. |
| CBOOT (4) | Bootstrap capacitor connection | Requires 470-nF ceramic cap to SW; enables high-side gate drive above VIN for full N-channel FET utilization. |
| VCC (5) | Internal LDO output | Bypass with capacitor to AGND; powers internal circuitry - no external loading permitted. |
| BIAS (6) | Optional LDO input | Tie to VOUT (3.3–28 V) or external 3.3/5 V rail to improve efficiency; bypass with 1–10 µF capacitor if used. |
| SYNC (7) | External clock input | Accepts 200 kHz–2.2 MHz square wave; enables EMI reduction via spread-spectrum or noise-sensitive timing alignment. |
| RT (8) | Frequency programming | Resistor to AGND sets fSW; open-circuit defaults to 500 kHz; accuracy ±10% with 1% resistor. |
| PGOOD (9) | Power-good indicator | Open-drain output; requires 10–100 kΩ pull-up; asserts after VOUT stabilizes within ±10% of target. |
| FB (10) | Feedback sense input | Monitors resistive divider midpoint; 1.011 V reference sets VOUT = 1.011 × (1 + RFBT/RFBB). |
| 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-compatible; 2.2 V typical turn-on threshold with 290 mV hysteresis - enables precise system-level UVLO. |
| VIN (13,14) | Main input supply | Connects to input capacitors and high-side FET; shortest possible path to CIN and PGND minimizes switching noise. |
| PGND (15,16) | Power ground | Low-impedance return for high-current paths; must be tied to AGND, PAD, and capacitor grounds with minimal loop area. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous rectification | Eliminates external Schottky diode, reducing conduction loss and board area - enables >90% efficiency at 1 A with 12 VIN/3.3 VOUT. |
| EMI-compliant design | Meets EN55022 Class B radiated and conducted emission limits without added shielding or complex filtering - verified on LM43603PWPEVM. |
| Pre-biased soft-start | Allows safe startup into pre-charged output capacitors - prevents reverse current flow and system reset glitches in multi-rail designs. |
| Stable with diverse output capacitors | Compatible with ceramic, polymer, tantalum, and aluminum electrolytic types - simplifies BOM management and cost optimization. |
| Internal compensation | Reduces external component count to only input/output caps, inductor, feedback divider, and optional RT/SS capacitors - accelerates layout and validation. |
Applications
| Industrial Power Supplies | Telecommunications Systems |
|---|---|
|
Use Scenario: 24-V DC distribution in programmable logic controllers (PLCs) powering 3.3-V I/O modules and 5-V microcontrollers. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 3.3 V/3 A with low quiescent current to extend uptime during brownouts. Use Value: 27-µA IQ enables >10-year battery backup for real-time clocks and nonvolatile memory retention during main power loss. |
Use Scenario: Intermediate bus conversion in 48-V telecom rectifiers supplying 12-V backplane and 5-V processor rails. IC Role / Device Role / Timing Role: High-efficiency point-of-load converter operating at 500 kHz with SYNC to align switching edges and reduce beat frequencies. Use Value: Adjustable frequency and synchronization minimize conducted EMI in dense multi-converter boards meeting CISPR 32 Class A limits. |
| Sub-AM Band Automotive | High Efficiency Point-Of-Load Regulation |
|
Use Scenario: Infotainment head unit power tree converting 9–16 V battery input to 3.3-V SoC core and 5-V USB peripherals. IC Role / Device Role / Timing Role: Wide-VIN buck regulator with precision enable (2.2 V UVLO) and thermal shutdown (160°C) for under-hood reliability. Use Value: BIAS pin tied to 5-V rail improves light-load efficiency by >5% versus VOUT-biased operation - critical for stop-start fuel economy. |
Use Scenario: FPGA core voltage supply requiring fast transient response and accurate 0.85-V ±1% regulation at up to 3 A. IC Role / Device Role / Timing Role: Synchronous buck controller with internal compensation and 1.011-V reference enabling <±1% output tolerance over temp and line. Use Value: Internal soft-start (4.1 ms) and PGOOD flag ensure controlled power-up sequencing with downstream logic and memory 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 |
|---|---|---|---|
| LM43602DSQT | 2-A rated, identical VSON-16 footprint and pinout; shares same 3.5–36-V input range and 200 kHz–2.2 MHz frequency adjustability. | Suitable where 2-A output suffices; lower RDS(on) (100 mΩ HS / 50 mΩ LS) improves efficiency at mid-load but lacks 3-A headroom. | Select LM43602DSQT when thermal margin or cost drives downcurrent requirements without changing PCB layout. |
| TPS54360DDAR | 3-A, 3.5–60-V input, SOIC-8 package; uses external compensation and requires external bootstrap diode - higher BOM count and larger solution size. | Preferred for ultra-wide VIN (up to 60 V) or legacy SOIC layouts; lacks integrated PGOOD, SYNC, and tracking features of LM43603DSUT. | Choose TPS54360DDAR only when input exceeds 36 V or SOIC-8 mechanical constraints override integration benefits. |
Compared with LM43602DSQT and TPS54360DDAR, the LM43603DSUT uniquely combines 3-A capability, VSON-16 wettable flanks for automated optical inspection, internal compensation, and EN-based precision UVLO - making it optimal for space-constrained, thermally demanding, and EMI-sensitive industrial and automotive point-of-load designs.
Availability
LM43603DSUT is available at Aetrix Electronics and suitable for industrial power supplies, telecommunications systems, and sub-AM band automotive applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM43603DSUT 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 and automotive-grade qualification.
The LM43603DSUT belongs to TI's LM436xx family of wide-input synchronous buck regulators, designed specifically for robust, compact, and EMI-compliant power conversion in harsh industrial and automotive environments.
FAQ
What is the maximum absolute input voltage rating for the LM43603DSUT?
The LM43603DSUT has an absolute maximum input voltage rating of 42 V across the VIN-to-PGND terminals. Operation beyond this limit risks permanent damage. The recommended operating range remains 3.5 V to 36 V, ensuring guaranteed performance and reliability per datasheet specifications. Always verify transient conditions - such as load dump in automotive systems - do not exceed 42 V, even momentarily.
Does the LM43603DSUT support output voltage tracking during power-up sequencing?
Yes, the LM43603DSUT supports output voltage tracking via the SS/TRK pin. By connecting this pin to an external voltage ramp (e.g., from another regulator's soft-start node), the LM43603DSUT's output follows that ramp, enabling coordinated power-up of multiple rails. This avoids reverse current flow and latch-up in FPGAs or processors with strict supply sequencing requirements - a confirmed function documented in Section 7.3 of the LM43603 datasheet.
What is the thermal resistance (RθJA) of the LM43603DSUT in its VSON-16 package?
The LM43603DSUT in the VSON-16 (DSU) package has a junction-to-ambient thermal resistance (RθJA) of 31.3°C/W, measured on a standard 4-layer JEDEC board. This value assumes proper PCB layout with thermal vias under the exposed pad connected to a solid ground plane. Real-world RθJA will vary based on copper area and airflow, but the 31.3°C/W baseline enables accurate junction temperature estimation using TJ = TA + (PDISS × RθJA).
Can the LM43603DSUT operate with ceramic output capacitors only?
Yes, the LM43603DSUT is explicitly designed to be stable with ceramic output capacitors - including X5R and X7R types - as well as polymer, tantalum, and aluminum electrolytic capacitors. This flexibility is enabled by its internal compensation and wide ESR tolerance, eliminating the need for minimum ESR requirements that constrain ceramic-only designs. Confirmed in datasheet Section 8.2.1 and Table 8-1.
What is the default switching frequency of the LM43603DSUT, and how is it adjusted?
The LM43603DSUT defaults to 500 kHz when the RT pin is left floating. To adjust frequency, connect a resistor from RT to AGND: values from ~100 kΩ (200 kHz) to ~10 kΩ (2.2 MHz) set the switching frequency, with ±10% accuracy using 1% resistors. The relationship is linear per Equation 10 in the datasheet, and frequency remains stable across input voltage and load variations.
LM43603DSUT 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)
LM43603DSUT FAQ
1.How can I place an order for LM43603DSUT through Aetrix?
Please submit a Request for Quotation (RFQ) for LM43603DSUT 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 LM43603DSUT reliable?
The price and inventory of LM43603DSUT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM43603DSUT is usually 5 days.
3.What payment methods are accepted for LM43603DSUT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM43603DSUT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM43603DSUT?
LM43603DSUT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM43603DSUT 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 LM43603DSUT?
For technical support, including LM43603DSUT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM43603DSUT requirements.
6.How does Aetrix verify that LM43603DSUT is sourced from the original manufacturer or authorized distributors?
All LM43603DSUT 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 LM43603DSUT meets industry standards.
7.What is the process for return or replacement of LM43603DSUT?
All LM43603DSUT units undergo pre-shipment inspection (PSI). If there is an issue with LM43603DSUT, 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 LM43603DSUT part is unused and in its original packaging.
Return procedure for LM43603DSUT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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