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Analog Devices Inc. LTC1649CS#TRPBF
- Part No.:
- LTC1649CS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1649CS#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,903
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Product details
Overview
LTC1649CS#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency, voltage-mode PWM step-down switching regulator controller optimized for 3.3V input and 1.26V–2.5V output at up to 20A. It drives two external N-channel MOSFETs, delivers 5V gate drive from 3.3V input via integrated charge pump, and achieves ±1% output regulation over line, load, and temperature. It is used in local regulation for distributed power systems supplying low-voltage microprocessors.
For engineers reviewing the LTC1649CS#TRPBF datasheet, LTC1649CS#TRPBF pinout, LTC1649CS#TRPBF application, or LTC1649CS#TRPBF equivalent, key selection considerations include its 200kHz fixed-frequency operation, no external current-sense resistor requirement, synchronous buck architecture, 16-lead SO package, and shutdown quiescent current below 10µA.
Technical Context
The LTC1649CS#TRPBF implements voltage-mode PWM control with a 200kHz internal oscillator and ±1% reference accuracy (1.265V typical). Its dual gate drivers (G1/G2) support synchronous N-MOSFET operation, while an internal charge pump generates 5V (VCPOUT = 4.8–5.2V) from VIN ≥2.7V to enable full gate drive for both high-side and low-side FETs.
It features three independent feedback paths: primary FB loop with transconductance amplifier (gm = 650 µmho), fast MIN/MAX comparators (±3% of VREF) for transient over/under-voltage protection, and ILIM loop using Q1's RDS(ON) for current limiting-eliminating external sense resistors. Soft-start is controlled by an external capacitor on SS pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 5V - supports direct 3.3V rail operation without pre-regulation |
| Output Voltage Range | 1.26V to 2.5V - set via external resistor divider on FB pin |
| Max Output Current | 20A - enabled by synchronous dual-N-MOSFET topology and robust gate drivers |
| Switching Frequency | 200kHz (typical) - fixed frequency minimizes inductor size and EMI filtering complexity |
| Feedback Reference | 1.265V ±1% - trimmed reference enables precise output regulation across temperature |
| Charge Pump Output | 5V ±0.2V at CPOUT - powers PVCC2 and VCC, enabling 5V gate drive from 3.3V input |
| Shutdown Current | <10µA - ultra-low quiescent draw preserves system standby power budget |
Pinout & Package
Package: 16-lead narrow SO (Small Outline), RoHS-compliant, surface-mount. Thermal resistance θJA = 110°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| G1 | High-side MOSFET gate driver output | Swings from PVCC1 to GND; drives Q1 gate; non-overlapping with G2 to prevent shoot-through |
| PVCC1 | Power supply for G1 driver | Must be ≥ VIN + 5V; typically generated via external flying capacitor charge pump from switching node |
| GND | Analog and power ground reference | Single-point ground connection critical for stability; ties to source of Q2 and system return path |
| FB | Output voltage feedback input | Connects to resistor divider; sets VOUT = 1.265V × (1 + R1/R2); high-impedance input |
| SHDN | Active-low shutdown control | TTL-compatible; <0.8V disables regulators and drops IQ to <10µA; 50µs minimum assertion time |
| SS | Soft-start timing and current-limit compensation | External capacitor to GND controls startup ramp rate and stabilizes ILIM loop during overload |
| VIN | Main input power supply | 2.7V–5V input; powers internal charge pump; bypass with 1µF ceramic capacitor near pin |
| C– / C+ | Flying capacitor terminals | 1µF ceramic capacitor between C– and C+ enables internal charge pump generating CPOUT |
| CPOUT | Regulated 5V charge pump output | Supplies PVCC2 and VCC; requires ≥10µF reservoir capacitance; remains active in shutdown |
| COMP | Error amplifier output / loop compensation node | Connect RC network to GND for stability; gm = 650 µmho; sensitive to layout and noise |
| IMAX | Current limit threshold setting | Internal 12µA pull-down; external resistor or voltage sets peak current trip point |
| IFB | Current sense input | Monitors voltage drop across Q1's RDS(ON); withstands up to 18V transient; protected by 1kΩ series resistor |
| VCC | Internal analog circuit supply | Powered from CPOUT; requires 10µF bypass; often filtered via 22Ω + 10µF RC from CPOUT |
| PVCC2 | Power supply for G2 driver | Typically tied to CPOUT; supplies 5V gate drive to Q2; bypass with 10µF capacitor |
| G2 | Low-side MOSFET gate driver output | Swings from PVCC2 to GND; drives Q2 gate; synchronous with G1 but non-overlapping |
Key Features
| Feature | Design Value |
|---|---|
| No external current-sense resistor | Uses RDS(ON) of high-side MOSFET (Q1) for current limiting - reduces BOM count and PCB area |
| Integrated 5V charge pump | Generates regulated 5V (CPOUT) from 3.3V input - enables logic-level N-MOSFETs without external boost |
| Synchronous buck architecture | Replaces freewheeling diode with Q2 - improves efficiency >90% at 15A and enables bidirectional output current |
| ±1% output regulation | Maintains accuracy over full line (2.7–5V), load (0–20A), and temperature (0°C to 70°C) range - suitable for precision logic rails |
| Fast transient protection | Dedicated MIN/MAX comparators respond within microseconds to ±3% output deviations - prevents overshoot/undershoot during load steps |
Applications
| Microprocessor Core Supply | Distributed Power System Local Regulator |
|---|---|
|
Use Scenario: Providing stable 2.5V/15A core voltage to a high-performance embedded microprocessor in a telecom baseband board. IC Role / Device Role / Timing Role: Primary step-down controller managing dynamic load transients and thermal derating in real time. Use Value: Delivers >90% efficiency at 10A–15A loads and maintains ±1% regulation during 5A/µs load steps - minimizing voltage droop and thermal stress. |
Use Scenario: Local 3.3V-to-1.8V conversion for FPGA I/O banks in a multi-rail industrial PLC backplane. IC Role / Device Role / Timing Role: Point-of-load (POL) regulator with fast transient response and minimal external components. Use Value: Eliminates need for external current-sense resistor and supports compact 16-pin SO layout - reducing footprint vs. discrete controller + sense solutions. |
| Low-Voltage Logic Rail Generator | High-Power DDR Memory Termination |
|
Use Scenario: Generating 1.26V for ASIC auxiliary logic in a battery-powered medical imaging subsystem. IC Role / Device Role / Timing Role: High-efficiency buck controller operating from a shared 3.3V intermediate bus. Use Value: Achieves <10µA shutdown current and 200kHz fixed frequency - simplifying EMI filter design and extending battery life. |
Use Scenario: Supplying 1.5V termination voltage to DDR3 memory modules in a server motherboard with tight thermal constraints. IC Role / Device Role / Timing Role: Synchronous buck controller delivering bidirectional current capability for ODT (On-Die Termination) compliance. Use Value: Supports sink current during memory read cycles - maintaining regulation without external Schottky diodes or complex control logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-current step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3728CUH#TRPBF | Higher VIN range (4.5–28V), 600kHz switching, supports multiphase operation - lacks integrated charge pump for sub-4V inputs | Designed for higher-input industrial/motor-control rails, not optimized for 3.3V-only systems | Select when input exceeds 4.5V and phase interleaving or faster transient response is required |
| MP2315DJ-LF-Z | Integrated power stage (25V/3A), no external MOSFETs needed - lower max current (3A vs. 20A), no programmable current limit | Targeted at space-constrained consumer applications, not high-power POL designs | Choose only for low-current, cost-sensitive designs where external FET flexibility and 20A capability are unnecessary |
Compared with LTC3728CUH#TRPBF and MP2315DJ-LF-Z, the LTC1649CS#TRPBF uniquely combines 3.3V-native operation, 20A scalability via external N-MOSFETs, and resistorless current sensing - making it irreplaceable for high-efficiency, low-input-voltage, high-current buck controllers.
Availability
LTC1649CS#TRPBF is available at Aetrix Electronics and suitable for high-power microprocessor core supplies, distributed power system local regulators, and low-voltage logic rail generation requiring stable component supply and long-term industrial lifecycle support.
Supply support for LTC1649CS#TRPBF 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 technical and manufacturing continuity for all Linear ICs, including precision power management products.
The LTC1649CS#TRPBF belongs to Linear's high-efficiency DC/DC controller family, designed specifically for low-input-voltage, high-output-current synchronous buck conversion in space- and thermally-constrained embedded systems.
FAQ
What is the maximum continuous output current supported by the LTC1649CS#TRPBF?
The LTC1649CS#TRPBF is rated for up to 20A continuous output current when paired with appropriately selected external N-channel MOSFETs, inductors, and thermal management. This rating assumes proper layout, adequate PCB copper area, and ambient temperature ≤70°C. The actual achievable current depends on external component selection, especially MOSFET RDS(ON), inductor saturation current, and output capacitor ESR.
Does the LTC1649CS#TRPBF require an external current-sense resistor?
No, the LTC1649CS#TRPBF does not require an external current-sense resistor. It implements current limiting by monitoring the voltage drop across the RDS(ON) of the high-side external MOSFET (Q1) via the IFB pin. This eliminates power loss and board space associated with shunt resistors, though accuracy varies with MOSFET temperature and unit-to-unit RDS(ON) tolerance.
Can the LTC1649CS#TRPBF operate from a 3.3V input to generate 1.26V output?
Yes, the LTC1649CS#TRPBF supports 3.3V input and can generate 1.26V output - the minimum specified feedback reference voltage. Output is set via resistor divider on the FB pin: VOUT = 1.265V × (1 + R1/R2). For 1.26V output, R2 must be significantly larger than R1, and layout must minimize noise coupling into the high-impedance FB node.
What is the purpose of the C+ and C– pins on the LTC1649CS#TRPBF?
The C+ and C– pins on the LTC1649CS#TRPBF connect to the terminals of a 1µF ceramic flying capacitor that enables the internal charge pump. This charge pump generates the regulated 5V output at CPOUT from the 3.3V VIN supply - essential for driving both external N-channel MOSFET gates. Incorrect capacitor value, type, or placement degrades CPOUT regulation and may cause gate drive failure.
Is the LTC1649CS#TRPBF pin-compatible with other members of the LTC1649 family?
Yes, the LTC1649CS#TRPBF shares identical pinout and electrical behavior with the LTC1649IS#TRPBF; both use the same 16-lead SO package and functional pin mapping. The only difference is operating temperature grade: CS is 0°C to 70°C, while IS is –40°C to 85°C. No PCB redesign is needed when upgrading from CS to IS for extended temperature applications.
LTC1649CS#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.7V ~ 5V
- Frequency - Switching:
- 200kHz
- Duty Cycle (Max):
- 93%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Soft Start
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LTC1649CS#TRPBF FAQ
1.How can I place an order for LTC1649CS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1649CS#TRPBF 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 LTC1649CS#TRPBF reliable?
The price and inventory of LTC1649CS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1649CS#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1649CS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1649CS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1649CS#TRPBF?
LTC1649CS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1649CS#TRPBF 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 LTC1649CS#TRPBF?
For technical support, including LTC1649CS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1649CS#TRPBF requirements.
6.How does Aetrix verify that LTC1649CS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1649CS#TRPBF 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 LTC1649CS#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1649CS#TRPBF?
All LTC1649CS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1649CS#TRPBF, 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 LTC1649CS#TRPBF part is unused and in its original packaging.
Return procedure for LTC1649CS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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