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Analog Devices Inc. LTC3608IWKG#PBF
- Part No.:
- LTC3608IWKG#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 52-VFQFN Exposed Pad
- Datasheet:
-
LTC3608IWKG#PBF.pdf
- Description:
- IC REG BUCK ADJ 8A 52QFN
- Quantity:
- Payment:
- Shipping:
Inventory:211
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Product details
Overview
LTC3608IWKG#PBF from Analog Devices (formerly Linear Technology) is an 8A monolithic synchronous step-down DC/DC converter with valley current mode control, operating from 4V to 18V input and delivering 2.5V output. It features adjustable switching frequency (via ION pin), programmable current limit (via VRNG), and ±1% 0.6V reference for precision regulation in point-of-load applications such as FPGA core supplies.
For engineers reviewing the LTC3608IWKG#PBF datasheet, LTC3608IWKG#PBF pinout, LTC3608IWKG#PBF application, or LTC3608IWKG#PBF equivalent, key selection criteria include its 52-lead 7mm × 8mm QFN package, tON(MIN) ≤ 100 ns for high step-down ratios, forced continuous/discontinuous mode control via FCB pin, and integrated N-channel MOSFETs eliminating external diode requirements.
Technical Context
The LTC3608IWKG#PBF implements a constant on-time valley current mode architecture with internal top and bottom N-channel MOSFETs (RDS(ON) = 10 mΩ / 8 mΩ), enabling stable operation with ceramic output capacitors and fast transient response. Its ITH pin serves dual roles: error amplifier compensation node and current threshold control point, where voltage (0–2.4 V) directly sets valley current limit.
Frequency is set implicitly by ION current and VON voltage (tON = VVON/IION × 10 pF), allowing VIN-compensated constant-frequency operation. Overvoltage protection triggers at ±10% VFB deviation, pulling PGOOD low and disabling M1 while holding M2 on until recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 8 A maximum continuous output current with thermal derating above 125°C junction temperature |
| Input Voltage Range | 4 V to 18 V - supports 12 V industrial rails and 5 V/3.3 V intermediate bus systems |
| Output Voltage Accuracy | ±1% over –40°C to 125°C - enables precise core voltage regulation for ASICs/FPGAs |
| Minimum On-Time | 60 ns - allows high step-down ratios (e.g., 12 V → 1.2 V at 500 kHz) without dropout |
| Switching Frequency Range | Adjustable from ~100 kHz to ~700 kHz via external RON - balances efficiency vs. size tradeoffs |
| Current Limit Programmability | VRNG pin adjusts max valley current from 5 A to 16 A - enables scalable current protection across load profiles |
| Shutdown Quiescent Current | 15 µA - minimizes system standby power in always-on embedded applications |
Pinout & Package
Package: 52-lead (7 mm × 8 mm) plastic QFN with exposed thermal pad (WKG). Designed for high-power density PCB layouts with multiple PVIN, PGND, and INTVCC pins to minimize IR drop and improve thermal dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN (Pins 1–7, 48–53) | Main input supply connection | Distributed high-current input path reduces trace resistance and improves EMI performance |
| SW (Pins 8, 33, 41–47, 55) | Switch node | High dv/dt node requiring tight layout to PGND; connects to inductor and bootstrap capacitor negative terminal |
| PGND (Pins 34–40) | Power ground return | Low-impedance return for high di/dt currents; must be connected directly to CIN(–) and CVCC(–) |
| ITH (Pin 18) | Error amplifier output & current threshold | 0–2.4 V control voltage sets valley current limit and provides loop compensation node |
| VRNG (Pin 17) | Valley current range select | 0.5–0.7 V input scales max valley current from 5 A to 16 A - critical for overload protection tuning |
| FCB (Pin 19) | Forced continuous mode enable | Ground = forced continuous (low-noise); INTVCC = discontinuous (high-efficiency light load) |
| PGOOD (Pin 16) | Open-drain power-good monitor | Asserts low when VOUT deviates >±10% - used for sequencing and fault reporting |
Key Features
| Feature | Design Value |
|---|---|
| True valley current mode control | Enables stable operation at very low duty cycles (<10%) without slope compensation |
| Programmable soft-start | External capacitor on RUN/SS pin controls ramp time (~3 s/µF) and prevents inrush current damage |
| Integrated gate drivers | Eliminates need for external driver ICs; supports bootstrap operation with Schottky diode and CB capacitor |
| Output overvoltage protection | Hardware comparator disables top MOSFET and holds bottom MOSFET on during overvoltage events |
| Thermal shutdown with hysteresis | Protects against sustained overload; resumes operation only after junction cools below 115°C |
| EXTVCC support | Accepts external 4.7–7 V supply to power INTVCC, reducing losses when secondary rail is available |
Applications
| FPGA Core Power Supply | Industrial PLC CPU Rail |
|---|---|
Use Scenario: Providing tightly regulated 1.2 V/8 A to Xilinx Kintex-7 FPGA core logic under dynamic load transients up to 6 A/µs. IC Role / Device Role / Timing Role: Primary point-of-load regulator with valley current mode control ensuring sub-100 ns response to load steps. Use Value: Maintains <±1% output accuracy across –40°C to 105°C ambient while supporting 500 kHz switching for compact filter design. |
Use Scenario: Generating 3.3 V/6 A for ARM Cortex-A9-based controller in factory automation system with 24 V DC input. IC Role / Device Role / Timing Role: High-reliability buck converter with programmable current limit and PGOOD sequencing for safe boot-up. Use Value: Enables robust operation under 100% load step with <200 mV undershoot and no external current sense resistor required. |
| Telecom Baseband Processor | Medical Imaging Sensor Bias |
Use Scenario: Delivering 2.5 V/8 A to LTE baseband SoC with strict ripple (<10 mVpp) and EMI requirements in dense RF board layout. IC Role / Device Role / Timing Role: Synchronous buck with forced continuous mode (FCB = GND) to suppress switching noise in adjacent RF sections. Use Value: Achieves >92% efficiency at full load while meeting CISPR-22 Class B conducted emissions with minimal filtering. |
Use Scenario: Supplying 5 V/4 A to CCD/CMOS sensor array in portable ultrasound device requiring ultra-low noise and high PSRR. IC Role / Device Role / Timing Role: Low-noise buck regulator with ceramic output capacitors and optimized loop compensation. Use Value: Delivers <50 µVrms output noise at 100 kHz bandwidth, preserving image SNR without post-regulation LDO stage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-current synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MPM3683-7 | 4.5–18 V input, 7 A output, integrated inductor, fixed 500 kHz frequency, no VRNG/FCB programmability | Suitable for space-constrained designs where board area > efficiency optimization priority | Select when simplified BOM and layout outweigh need for current limit tuning or light-load mode selection |
| TPS548D22 | 4.5–18 V input, 8 A output, D-CAP3 control, 0.6 V reference, pin-compatible 52-QFN but different pin functions (e.g., no VRNG) | Requires different compensation network; lacks valley current foldback and EXTVCC support | Choose for TI ecosystem compatibility and digital PMBus monitoring, not for analog current limit adjustment |
Compared with MPM3683-7 and TPS548D22, the LTC3608IWKG#PBF uniquely combines programmable valley current limiting (VRNG), selectable conduction mode (FCB), and valley current mode control for superior transient response in high-dynamic-load applications - making it preferred for FPGA, ASIC, and high-performance processor rails where analog flexibility matters.
Availability
LTC3608IWKG#PBF is available at Aetrix Electronics and suitable for FPGA core power, industrial PLC CPU rails, and telecom baseband processor supplies requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3608IWKG#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3608IWKG#PBF belongs to Linear's monolithic high-current buck converter product line, designed specifically for demanding point-of-load applications requiring precision regulation, fast transient response, and robust fault protection in harsh environments.
FAQ
What is the maximum junction temperature rating for the LTC3608IWKG#PBF?
The LTC3608IWKG#PBF has a guaranteed operating junction temperature range of –40°C to 125°C. Thermal shutdown activates at TJ ≈ 150°C with hysteresis, and the device resumes normal operation only after cooling below ~115°C. The WKG package's θJA is 29°C/W on a standard 4-layer JEDEC test board.
How does the VRNG pin affect current limiting in the LTC3608IWKG#PBF?
The VRNG pin on the LTC3608IWKG#PBF sets the maximum valley current limit between 5 A and 16 A by applying 0.5 V to 0.7 V. At 0.5 V, typical IVALLEY(MAX) = 5 A; at 0.7 V, it reaches 16 A. This directly determines maximum average output current (IOUT(MAX) ≈ IVALLEY(MAX) + ½ΔIL) and must be configured before final layout to avoid thermal overstress.
Can the LTC3608IWKG#PBF operate with a 3.3 V input supply?
No - the LTC3608IWKG#PBF requires a minimum input voltage of 4 V per its absolute maximum ratings and functional specifications. Attempting operation below 4 V will trigger undervoltage lockout (UVLO), preventing switching. For 3.3 V input applications, consider the LTC3607 or other lower-VIN buck regulators.
What is the purpose of the FCB pin on the LTC3608IWKG#PBF?
The FCB (Forced Continuous) pin on the LTC3608IWKG#PBF selects light-load conduction mode: grounding FCB forces continuous conduction (reducing EMI), tying FCB to INTVCC enables discontinuous mode (improving light-load efficiency), and connecting to a resistive divider from a secondary output supports multi-rail tracking. This pin directly affects audible noise and efficiency tradeoffs below ~1 A load.
Does the LTC3608IWKG#PBF require an external bootstrap diode?
Yes - the LTC3608IWKG#PBF requires an external Schottky diode (e.g., 1N5819) between INTVCC and BOOST to recharge the bootstrap capacitor (CB) during each switching cycle. This diode must have low forward voltage (<0.4 V) and fast recovery to maintain gate drive integrity at high frequencies and prevent BOOT voltage collapse.
LTC3608IWKG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 52-VFQFN 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):
- 4V
- Voltage - Input (Max):
- 18V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 17.82V
- Current - Output:
- 8A
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 52-QFN-Multipad (7x8)
LTC3608IWKG#PBF FAQ
1.How can I place an order for LTC3608IWKG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3608IWKG#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 LTC3608IWKG#PBF reliable?
The price and inventory of LTC3608IWKG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3608IWKG#PBF is usually 5 days.
3.What payment methods are accepted for LTC3608IWKG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3608IWKG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3608IWKG#PBF?
LTC3608IWKG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3608IWKG#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 LTC3608IWKG#PBF?
For technical support, including LTC3608IWKG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3608IWKG#PBF requirements.
6.How does Aetrix verify that LTC3608IWKG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3608IWKG#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 LTC3608IWKG#PBF meets industry standards.
7.What is the process for return or replacement of LTC3608IWKG#PBF?
All LTC3608IWKG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3608IWKG#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 LTC3608IWKG#PBF part is unused and in its original packaging.
Return procedure for LTC3608IWKG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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