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Analog Devices Inc. LTC3608EWKG#PBF
- Part No.:
- LTC3608EWKG#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 52-VFQFN Exposed Pad
- Datasheet:
-
LTC3608EWKG#PBF.pdf
- Description:
- IC REG BUCK ADJ 8A 52QFN
- Quantity:
- Payment:
- Shipping:
Inventory:468
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Product details
Overview
LTC3608EWKG#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.
For engineers reviewing the LTC3608EWKG#PBF datasheet, LTC3608EWKG#PBF pinout, LTC3608EWKG#PBF application, or LTC3608EWKG#PBF equivalent, key selection criteria include minimum on-time (≤100 ns), forced continuous/discontinuous mode control (FCB pin), power-good monitoring (PGOOD), and thermal performance in its 7mm × 8mm 52-lead QFN package.
Technical Context
The LTC3608EWKG#PBF employs a constant on-time valley current mode architecture with internal N-channel MOSFETs (RDS(ON) = 10 mΩ top / 8 mΩ bottom), enabling stable operation at high step-down ratios and fast transient response. Its tON(MIN) ≤ 100 ns supports ultra-low duty cycle operation down to ~14% at 12VIN/2.5VOUT.
Fault protection includes foldback current limiting, output overvoltage detection (±10% window), and optional short-circuit shutdown timer via RUN/SS pin. Soft-start is implemented with external capacitor on RUN/SS, and INTVCC can be powered externally via EXTVCC ≥ 4.7V to improve efficiency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 8A max continuous - supports high-density PoL regulation without external MOSFETs |
| Input Voltage Range | 4V to 18V - compatible with 5V, 12V, and 15V intermediate bus systems |
| Feedback Reference | 0.6V ±1% - enables accurate VOUT setting from 0.6V to >5V using resistive divider |
| Min On-Time | ≤100 ns - allows stable 2.5V output from 12V input (duty cycle ~21%) |
| Switching Frequency | Adjustable via RON on ION pin - supports 100–700 kHz range for size/efficiency tradeoff |
| Current Limit Range | Programmable 5–16A via VRNG voltage (0.5V–0.7V) - enables precise ILIM tuning for thermal margin |
| Power Good Threshold | ±10% of VFB - provides reliable system sequencing and fault indication |
Pinout & Package
Package: 7mm × 8mm, 52-lead plastic QFN with exposed thermal pad (WKG). Designed for high-power dissipation with θJA = 29°C/W (simulated) and θJC = 1°C/W (with heatsink).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN (1–7, 48–53) | Main input supply connection | Multiple parallel pins reduce IR drop and thermal resistance for 8A input current path |
| SW (8, 33, 41–47, 55) | Switch node | High-current switching node tied to inductor; requires low-inductance layout to minimize EMI |
| PGND (34–40) | Power ground return | Dedicated low-impedance ground for high di/dt paths; must connect directly to CIN(–) and CVCC(–) |
| ITH (18) | Error amplifier compensation & current threshold | Analog control node: 0–2.4V sets valley current limit; also used for loop compensation |
| VRNG (17) | Valley current limit range select | 0.5V–0.7V input adjusts max valley current from 5A to 16A - critical for thermal design |
| FCB (19) | Forced continuous/discontinuous mode control | GND = forced continuous (low-noise); INTVCC = discontinuous (high-efficiency light load) |
| PGOOD (16) | Open-drain power-good monitor | Asserts low when VFB deviates >±10% - used for system enable/disable sequencing |
Key Features
| Feature | Design Value |
|---|---|
| True valley current mode control | Enables stable ceramic-capacitor output filtering and eliminates need for external current-sense resistor |
| Adjustable minimum on-time (≤100 ns) | Supports high step-down ratios (e.g., 12V→2.5V) without pulse-skipping or instability |
| Programmable current limit via VRNG | Allows precise thermal derating: set 12A limit for 70°C ambient instead of fixed 16A max |
| EXTVCC switchover (≥4.7V) | Reduces power loss by bypassing internal 5V LDO - improves full-load efficiency by ~0.5–1.0% |
| Soft-start with external capacitor | Enables controlled inrush current ramp (≈3 s/µF) - prevents input rail collapse during startup |
Applications
| Telecom Point-of-Load | Industrial FPGA Core Supply |
|---|---|
Use Scenario: Regulating 2.5V core voltage for high-speed FPGA I/O banks from a 12V backplane. IC Role / Device Role / Timing Role: Primary synchronous buck regulator with fast transient response to handle 0–6A dynamic load steps. Use Value: 8A rating and ≤100 ns min on-time ensure regulation stability during 200 ns load transients without droop exceeding 50 mV. | Use Scenario: Powering ASIC digital cores requiring tightly regulated 2.5V with sequencing and fault reporting. IC Role / Device Role / Timing Role: Main DC/DC controller with PGOOD output synchronized to system reset logic. Use Value: ±10% PGOOD window and programmable soft-start enable safe, repeatable power-up across temperature and voltage corners. |
| Automotive ADAS Domain Controller | Medical Imaging Sensor Interface |
Use Scenario: Converting 12V vehicle battery to 2.5V for radar processor SoCs in harsh thermal environments. IC Role / Device Role / Timing Role: High-reliability buck converter with foldback current limiting and overvoltage protection. Use Value: -40°C to 125°C junction rating and internal current limit clamping prevent latch-up during cold-crank or load-dump events. | Use Scenario: Providing low-noise 2.5V bias to high-resolution analog front-end sensors in portable imaging devices. IC Role / Device Role / Timing Role: Low-EMI power stage with forced continuous mode (FCB = GND) to suppress switching noise near sensitive ADCs. Use Value: Discontinuous mode disabled ensures constant-frequency operation, eliminating beat frequencies that degrade SNR in sensor signal chains. |
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 | Integrated inductor (3.5A), fixed 500kHz fSW, no VRNG/FCB control | Limited to lower current; lacks programmable current limit and mode control | Choose for space-constrained designs where 3.5A suffices and layout simplicity outweighs flexibility |
| TPS548D22 | 8A, 4–18V, D-CAP3 control, 0.6V ref, but 40-pin QFN (6×6mm) and no EXTVCC switchover | Higher pin density, no external VCC option - less efficient at full load vs LTC3608EWKG#PBF | Prefer when using TI ecosystem tools or needing D-CAP3's ultra-fast transient response without external compensation |
Compared with MPM3683-7 and TPS548D22, the LTC3608EWKG#PBF offers unique combination of 8A capability, sub-100 ns on-time, VRNG-based current limit tuning, and EXTVCC efficiency boost - making it optimal for thermally demanding, high-flexibility PoL designs.
Availability
LTC3608EWKG#PBF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial FPGA power, and automotive ADAS applications requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 125°C.
Supply support for LTC3608EWKG#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 full product support, including datasheets, SPICE models, and application notes for legacy Linear parts.
The LTC3608EWKG#PBF belongs to Linear's high-current monolithic buck converter family, designed specifically for demanding point-of-load regulation where efficiency, thermal performance, and design flexibility are critical.
FAQ
What is the maximum recommended junction temperature for the LTC3608EWKG#PBF?
The LTC3608EWKG#PBF is rated for operation up to 125°C junction temperature. Thermal design must ensure TJ ≤ 125°C under worst-case conditions (max load, max ambient, minimal airflow). The WKG package's θJA = 29°C/W (simulated) and θJC = 1°C/W (with heatsink) guide PCB copper area and thermal vias placement. Exceeding 125°C risks permanent degradation of the internal MOSFETs and control circuitry in the LTC3608EWKG#PBF.
How do I configure the LTC3608EWKG#PBF for forced continuous conduction mode (FCCM)?
To configure the LTC3608EWKG#PBF for forced continuous conduction mode, tie the FCB pin (Pin 19) to ground. This disables discontinuous mode operation, ensuring both top and bottom MOSFETs switch continuously even at light loads - reducing EMI and output voltage ripple at the cost of slightly lower light-load efficiency. Do not leave FCB floating; grounding provides deterministic FCCM behavior across temperature and line conditions in the LTC3608EWKG#PBF.
Can the LTC3608EWKG#PBF regulate output voltages below 0.6V?
No, the LTC3608EWKG#PBF cannot regulate output voltages below 0.6V because its internal feedback reference is fixed at 0.6V ±1%. The output voltage is set by VOUT = 0.6V × (1 + R2/R1), so the lowest achievable regulated output is 0.6V (when R2 = 0 and R1 is omitted). For sub-0.6V applications, an external reference or different controller architecture is required - the LTC3608EWKG#PBF is not designed for such use cases.
What is the purpose of the VRNG pin on the LTC3608EWKG#PBF, and how is it used?
The VRNG pin (Pin 17) on the LTC3608EWKG#PBF sets the maximum valley current limit, which directly determines the achievable output current. Applying 0.5V–0.7V via a resistive divider from INTVCC scales the current limit from 5A to 16A. Grounding VRNG defaults to 0.7V (16A typical). This pin enables thermal derating - e.g., setting 10A limit for constrained airflow - and must never be left floating. The VRNG voltage directly affects current foldback behavior during overload in the LTC3608EWKG#PBF.
Does the LTC3608EWKG#PBF require an external bootstrap diode?
Yes, the LTC3608EWKG#PBF requires an external Schottky bootstrap diode (DB) connected from INTVCC to BOOST (Pin 11) to recharge the bootstrap capacitor (CB) during each switching cycle. This diode must have low forward voltage (<0.5V) and fast recovery (<30 ns) to maintain gate drive integrity for the high-side MOSFET. Omitting or misselecting this diode causes BOOT voltage collapse, leading to erratic switching or complete failure of the LTC3608EWKG#PBF.
LTC3608EWKG#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)
LTC3608EWKG#PBF FAQ
1.How can I place an order for LTC3608EWKG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3608EWKG#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 LTC3608EWKG#PBF reliable?
The price and inventory of LTC3608EWKG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3608EWKG#PBF is usually 5 days.
3.What payment methods are accepted for LTC3608EWKG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3608EWKG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3608EWKG#PBF?
LTC3608EWKG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3608EWKG#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 LTC3608EWKG#PBF?
For technical support, including LTC3608EWKG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3608EWKG#PBF requirements.
6.How does Aetrix verify that LTC3608EWKG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3608EWKG#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 LTC3608EWKG#PBF meets industry standards.
7.What is the process for return or replacement of LTC3608EWKG#PBF?
All LTC3608EWKG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3608EWKG#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 LTC3608EWKG#PBF part is unused and in its original packaging.
Return procedure for LTC3608EWKG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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