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Analog Devices Inc. LTC3603IUF#PBF
- Part No.:
- LTC3603IUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3603IUF#PBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,969
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Product details
Overview
LTC3603IUF#PBF from Analog Devices (formerly Linear Technology) is a monolithic synchronous step-down DC/DC converter delivering up to 2.5A output current with 45mΩ top and 85mΩ bottom MOSFETs, adjustable 0.6V–14.5V output, and 300kHz–3MHz programmable switching frequency. It operates from 4.5V to 15V input and integrates OPTI-LOOP® compensation for optimized transient response in point-of-load power supplies for FPGA core rails.
For engineers reviewing the LTC3603IUF#PBF datasheet, LTC3603IUF#PBF pinout, LTC3603IUF#PBF application, or LTC3603IUF#PBF equivalent, key selection considerations include its 20-lead 4mm × 4mm QFN package with exposed SGND pad, Burst Mode® vs forced continuous mode trade-offs, PGOOD monitoring capability, and thermal performance (θJA = 37°C/W) in industrial temperature range (–40°C to 125°C).
Technical Context
The LTC3603IUF#PBF employs constant-frequency current-mode control with internal slope compensation recovery to maintain stable peak inductor current across duty cycles >30%. Its dual-MOSFET architecture supports 99% maximum duty cycle in dropout, enabled by periodic 85ns bottom-switch activation to refresh the BOOST capacitor.
It features dual operating modes: forced continuous mode (SYNC/MODE tied to INTVCC) for low-noise applications, and externally clamped Burst Mode® (SYNC/MODE at 0.42V–1V) enabling 75µA quiescent current. The ITH pin serves as error amplifier compensation node and burst comparator input, while TRACK/SS supports voltage sequencing and external soft-start via 1.2µA current source.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 15V DC - supports wide-range industrial and telecom inputs without pre-regulation |
| Output Current | Up to 2.5A - sufficient for mid-power FPGA cores, DSPs, and ASICs |
| Switch RDS(ON) | 45mΩ (top), 85mΩ (bottom) - enables high efficiency (>90% at 1A, 12VIN/3.3VOUT) without external diode |
| Feedback Reference | 0.6V ±1% - allows precise low-voltage regulation down to 0.6V for modern logic rails |
| Quiescent Current | 75µA in Burst Mode - extends battery life in portable instrumentation |
| Switching Frequency | 300kHz to 3MHz - selectable via RT resistor or external clock sync for EMI management |
| Thermal Resistance | θJA = 37°C/W - requires PCB thermal pad connection to SGND for rated performance |
Pinout & Package
Package: 20-lead (4mm × 4mm) plastic QFN with exposed SGND pad (Pin 21), rated for –40°C to 125°C junction temperature. Exposed pad must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN (Pins 1, 2) | Power Input Supply | Primary input rail connection; requires local ceramic decoupling to PGND |
| SW (Pins 16–19) | Switch Node | Connection to inductor; high dv/dt node requiring minimized trace area and length |
| PGND (Pins 12–15) | Power Ground | High-current return path for both switches; separate from SGND to reduce noise coupling |
| SGND (Pins 9, 21) | Signal Ground | Reference for feedback, error amp, and logic; exposed pad (Pin 21) must be connected to SGND plane |
| INTVCC (Pin 3) | Internal 5V LDO Output | Supplies internal circuitry; can power external bias components or SYNC/MODE pull-up |
| SYNC/MODE (Pin 4) | Mode Select / Clock Sync | Configures operation: ground = pulse-skip, 0.42–1V = Burst Mode, INTVCC = forced continuous |
| PGOOD (Pin 5) | Open-Drain Power Good | Asserts high when VOUT is within ±10%; requires external pull-up for system enable sequencing |
| RT (Pin 6) | Frequency Set | Connects to ground via resistor to set oscillator frequency (ROSC = 1.15×10¹¹/f − 10kΩ) |
| ITH (Pin 7) | Error Amplifier Compensation | Compensation node for loop stability; also monitored by burst comparator in light-load mode |
| VFB (Pin 8) | Feedback Input | Senses resistive divider output; regulates to 0.6V reference for accurate output programming |
| RUN (Pin 10) | Enable Control | Active-high enable; threshold 0.4–1.1V; tie to PVIN for always-on operation |
| TRACK/SS (Pin 11) | Tracking / Soft-Start | Enables voltage sequencing (track external ramp) or external soft-start (capacitor to GND) |
| BOOST (Pin 20) | Bootstrap Supply | Charged via internal diode during SW low phase; powers top gate driver for high-side N-MOSFET |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows single-pole compensation network to optimize transient response across wide load and output capacitor ranges without sacrificing stability |
| Adjustable Burst Mode® Clamp | External voltage on SYNC/MODE sets minimum peak inductor current, enabling precise control of output ripple vs efficiency trade-off |
| 99% Maximum Duty Cycle | Supports ultra-low dropout operation (e.g., 5VIN → 4.8VOUT) by forcing bottom switch on periodically to refresh BOOST capacitor |
| Power Good Output | Open-drain PGOOD provides system-level fault detection and enables safe power sequencing with microprocessors and FPGAs |
| Overtemperature Protection | Shuts down both switches at ~150°C junction temperature and auto-restarts below 115°C - protects against thermal runaway in enclosed systems |
Applications
| FPGA Core Power Supply | DSP Processor Rail |
|---|---|
|
Use Scenario: Providing tightly regulated 1.0V/1.2V core voltage to Xilinx Artix-7 or Intel Cyclone V FPGA under dynamic load transients up to 2A/µs. IC Role / Device Role / Timing Role: Primary synchronous buck regulator with fast transient response enabled by OPTI-LOOP® and low-ESR ceramic output capacitors. Use Value: Maintains <±1% output regulation during 100mA–2.5A load steps, preventing configuration errors or logic corruption in high-speed digital logic. |
Use Scenario: Generating 1.8V I/O supply for TI C66x DSPs in wireless baseband processing units with strict EMI limits. IC Role / Device Role / Timing Role: Synchronous step-down converter operating in forced continuous mode synchronized to system clock to avoid spectral interference. Use Value: Eliminates subharmonic switching noise in sensitive analog front-end bands while sustaining 92% efficiency at 1.5A load. |
| Portable Test Instrumentation | Industrial PLC I/O Module |
|
Use Scenario: Powering mixed-signal ADC/DAC subsystems in handheld multimeters and oscilloscope probes with battery-derived 7.2V–12V input. IC Role / Device Role / Timing Role: High-efficiency buck converter in Burst Mode® to extend lithium-ion battery runtime between charges. Use Value: Achieves 86% efficiency at 10mA load and 75µA quiescent current, enabling >100 hours of standby operation per charge. |
Use Scenario: Delivering robust 3.3V logic rail to isolated CAN and RS-485 transceivers in factory automation controllers exposed to 40°C–85°C ambient. IC Role / Device Role / Timing Role: Industrial-grade DC/DC regulator with overvoltage, overtemperature, and short-circuit protection. Use Value: Sustains uninterrupted operation under 16.5V PVIN transients and survives sustained 125°C junction temperature with no derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2315DJ-LF-Z | 2A max output, fixed 3.3V/5V options only; no PGOOD or TRACK/SS; 2000kHz max frequency | Lacks voltage tracking, soft-start, and power-good signaling - unsuitable for FPGA sequencing or safety-critical systems | Select only for cost-sensitive, fixed-output, low-complexity applications where full feature set is unnecessary |
| TPS54228DDAR | 2.5A, 4.5–18V input, but uses external MOSFETs; no integrated switches; requires more board space and design effort | Higher design complexity and BOM count; better for high-temp or high-reliability custom designs needing discrete switch control | Prefer when thermal margin exceeds 125°C or when discrete switch optimization (e.g., GaN) is required |
Compared with MP2315DJ-LF-Z and TPS54228DDAR, the LTC3603IUF#PBF delivers superior integration (dual MOSFETs + PGOOD + TRACK/SS + OPTI-LOOP®), tighter output tolerance (±1% vs ±2%), and guaranteed industrial temperature operation - making it optimal for space-constrained, high-performance embedded power rails.
Availability
LTC3603IUF#PBF is available at Aetrix Electronics and suitable for FPGA core supplies, DSP processor rails, and industrial PLC I/O modules requiring stable component supply across extended temperature and long production lifecycles.
Supply support for LTC3603IUF#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains its high-performance power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3603IUF#PBF belongs to Linear's monolithic synchronous buck regulator family, designed specifically for compact, high-efficiency point-of-load conversion in FPGA, ASIC, and DSP applications demanding precision regulation and robust protection.
FAQ
What is the maximum junction temperature rating for the LTC3603IUF#PBF?
The LTC3603IUF#PBF has a maximum junction temperature (TJMAX) of 125°C and incorporates overtemperature protection that disables both power switches if junction temperature reaches approximately 150°C. It automatically restarts once temperature falls below 115°C. This thermal shutdown behavior ensures reliability in enclosed or high-ambient environments where the LTC3603IUF#PBF may operate near its thermal limits.
Can the LTC3603IUF#PBF be used in forced continuous mode, and how is it configured?
Yes, the LTC3603IUF#PBF supports forced continuous conduction mode (CCM) by connecting the SYNC/MODE pin to INTVCC (Pin 3). This configuration disables Burst Mode® operation, eliminating low-load switching discontinuities and reducing output voltage ripple and EMI. Forced continuous mode is ideal for noise-sensitive signal processing applications, though it increases light-load quiescent current to ~500µA versus 75µA in Burst Mode® - a trade-off explicitly documented in the LTC3603IUF#PBF datasheet.
What is the purpose of the exposed pad (Pin 21) on the LTC3603IUF#PBF QFN package?
The exposed pad (Pin 21) on the LTC3603IUF#PBF is electrically connected to SGND and serves as the primary thermal path to the PCB. It must be soldered to a dedicated SGND copper pour with multiple thermal vias to achieve the specified θJA = 37°C/W. Failure to connect this pad results in excessive junction temperature rise, potential thermal shutdown, and violation of the device's guaranteed specifications - a requirement explicitly stated in the LTC3603IUF#PBF package drawing and thermal design guidelines.
How does the LTC3603IUF#PBF implement voltage tracking for multi-rail systems?
The LTC3603IUF#PBF implements voltage tracking via the TRACK/SS pin (Pin 11), which accepts an external ramp voltage. When the applied voltage is below 0.6V, the output regulates to match that ramp; above 0.6V, regulation reverts to the internal 0.6V reference. This enables precise sequencing of core and I/O rails in FPGAs or microprocessors. The LTC3603IUF#PBF also sources a 1.2µA current from TRACK/SS, allowing external capacitor-based soft-start - a capability confirmed in the LTC3603IUF#PBF pin function table and applications section.
What protection features are integrated into the LTC3603IUF#PBF?
The LTC3603IUF#PBF integrates overtemperature shutdown (trip ~150°C), PVIN overvoltage protection (shuts down above ~16.5V), output overvoltage protection (via PGOOD monitoring and top-FET disable), and short-circuit protection (valley-current limit at 4.5A). These protections are hardware-based and active across the full –40°C to 125°C operating range - verified in the Absolute Maximum Ratings and Electrical Characteristics tables of the official LTC3603IUF#PBF datasheet.
LTC3603IUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 15V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 14.5V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x4)
LTC3603IUF#PBF FAQ
1.How can I place an order for LTC3603IUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3603IUF#PBF 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 LTC3603IUF#PBF reliable?
The price and inventory of LTC3603IUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3603IUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3603IUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3603IUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3603IUF#PBF?
LTC3603IUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3603IUF#PBF 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 LTC3603IUF#PBF?
For technical support, including LTC3603IUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3603IUF#PBF requirements.
6.How does Aetrix verify that LTC3603IUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3603IUF#PBF 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 LTC3603IUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3603IUF#PBF?
All LTC3603IUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3603IUF#PBF, 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 LTC3603IUF#PBF part is unused and in its original packaging.
Return procedure for LTC3603IUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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