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Analog Devices Inc. LTC1735CGN-1#TRPBF
- Part No.:
- LTC1735CGN-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1735CGN-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,182
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Product details
Overview
LTC1735CGN-1 from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller optimized for CPU core power delivery in mobile computing systems. It delivers 0.8V to 7V output with ±1% accuracy, supports 3.5V–36V input, operates up to 500kHz (synchronizable), and features OPTI-LOOP™ compensation for stable transient response across wide output capacitance/ESR ranges - used in SpeedStep-enabled Pentium III notebook DC/DC converters.
For engineers reviewing the LTC1735CGN-1 datasheet, LTC1735CGN-1 pinout, LTC1735CGN-1 application, or LTC1735CGN-1 equivalent, key selection criteria include its programmable current limit via RSENSE, 99% dropout duty cycle, PGOOD window comparator (±7.5%), Burst Mode™ operation for light-load efficiency, and dual N-MOSFET gate drive capability in 16-lead SSOP package.
Technical Context
The LTC1735CGN-1 implements a constant-frequency, current-mode control architecture with an internal transconductance error amplifier (gm = 1.3 mmho) and dual current comparators for peak-current sensing. Its OPTI-LOOP™ compensation allows loop stability optimization independent of output capacitor ESR, enabling robust performance with ceramic or polymer capacitors.
It integrates synchronized dual gate drivers (TG/BG) supporting floating top-side drive via BOOST pin, internal 5.2V LDO (INTVCC), EXTVCC switchover at 4.7V, and a programmable soft-start via RUN/SS pin. Protection includes foldback current limiting, output overvoltage crowbar (0.84–0.88V VOSENSE threshold), latched short-circuit shutdown, and undervoltage lockout (3.5V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 0.8V to 7V - set by external resistor divider on VOSENSE; enables dynamic voltage scaling for CPU cores. |
| Input Voltage Range | 3.5V to 36V - supports wide-input industrial and mobile battery-fed systems including 5V, 12V, and 24V rails. |
| Feedback Accuracy | ±1% at VOSENSE = 0.8V - ensures tight regulation critical for low-voltage CPU core supplies. |
| PGOOD Window | ±7.5% of programmed VOUT - meets Intel Mobile CPU specification for power-good assertion timing and sequencing. |
| Max Duty Cycle | 99.4% - enables ultra-low dropout operation during input voltage sag or high load conditions. |
| Oscillator Frequency | 265–335 kHz (COSC = 47pF) - externally set and synchronizable up to 500kHz for EMI reduction and multi-rail coordination. |
| Shutdown Current | <25 µA - enables micropower system-level sleep modes without compromising startup reliability. |
Pinout & Package
Package: 16-lead narrow SSOP (GN), 5.3mm × 6.2mm, 0.635mm pitch, RoHS-compliant. Thermal resistance θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC (1) | Oscillator timing node | Connects external capacitor to set switching frequency; determines fOSC and sync range. |
| RUN/SS (2) | Soft-start ramp & enable control | Capacitor sets soft-start time (~1.25 s/µF); <1.5V disables regulator and initiates latchoff under fault. |
| ITH (3) | Error amplifier output | Controls peak inductor current; voltage range 0–2.4V directly scales current limit threshold. |
| PGOOD (4) | Open-drain status & sync input | Pulled low when VOSENSE outside ±7.5%; external clock input enables synchronization and forces continuous mode. |
| SENSE– (5), SENSE+ (6) | Differential current sense inputs | Monitor voltage across RSENSE; built-in offset enables accurate current limit setting (60–85 mV range). |
| VOSENSE (7) | Feedback voltage input | Receives scaled output voltage; referenced to 0.8V internal bandgap for precise regulation. |
| SGND (8) | Small-signal ground reference | Single-point tie point for feedback network, COSC, CSS, and compensation components to minimize noise coupling. |
| EXTVCC (9) | External bias supply input | Switches internal LDO off when >4.7V; enables efficient self-biasing from converter output or auxiliary rail. |
| PGND (10) | Power ground return | Low-impedance return path for bottom MOSFET source, Schottky cathode, and CIN negative terminal. |
| BG (11) | Bottom gate driver output | Drives N-MOSFET source-follower configuration; swing from PGND to INTVCC (5.2V). |
| INTVCC (12) | Internal LDO output | 5.0–5.4V regulated supply for logic and drivers; requires 1µF ceramic + ≥4.7µF tantalum decoupling. |
| VIN (13) | Main input power supply | 3.5–36V input; must be closely decoupled to PGND with low-ESR bulk and ceramic capacitors. |
| SW (14) | Switch node | Connects to inductor and bootstrap capacitor; swings from ~–0.4V (Schottky drop) to VIN. |
| BOOST (15) | Floating top-gate supply | Return for bootstrap capacitor; voltage swing = INTVCC superimposed on SW node. |
| TG (16) | Top gate driver output | Drives N-MOSFET gate with floating driver; swing = INTVCC referenced to SW node. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ Compensation | Enables stable loop response across diverse output capacitor types (ceramic, polymer, electrolytic) without redesigning compensation network. |
| Programmable Current Limit | Set via external RSENSE (e.g., 4mΩ → 75mV threshold → ~18.75A peak); supports foldback during short-circuit events. |
| Burst Mode™ Operation | Delivers >85% efficiency at 10mA load (VIN=10V, VOUT=3.3V); reduces quiescent current and audible noise in light-load states. |
| 99% Dropout Duty Cycle | Maintains regulation with VIN–VOUT as low as 100mV at full load; critical for battery-powered systems under brownout. |
| Remote Output Sensing | VOSENSE pin accepts Kelvin-connected feedback to reject PCB trace IR drop and ensure accurate load-point regulation. |
| Logic-Controlled Shutdown | IQ < 25µA in shutdown; RUN/SS pin compatible with standard GPIOs for system-level power sequencing. |
Applications
| Mobile CPU Core Power | Notebook System Rail |
|---|---|
Use Scenario: Dynamic voltage scaling for Intel Pentium III processors with SpeedStep™ technology in ultraportable notebooks. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing CPU VCC with real-time VID transitions between 1.35V and 1.60V. Use Value: ±1% output accuracy and ±7.5% PGOOD window ensure compliance with Intel mobile CPU specifications for safe voltage transitions and thermal management. | Use Scenario: Main 1.6V/12A core supply in fanless tablet PCs operating from 4.5–24V battery input. IC Role / Device Role / Timing Role: High-efficiency step-down controller driving dual FDS6680A MOSFETs with remote sensing and programmable soft-start. Use Value: 99% duty cycle sustains regulation during battery discharge; Burst Mode™ extends runtime at idle without compromising transient response. |
| Wireless Baseband Power | Industrial FPGA Core Supply |
Use Scenario: Low-noise 1.2V/3A supply for cellular baseband ICs in LTE modems requiring EMI-controlled switching. IC Role / Device Role / Timing Role: Synchronizable buck controller locked to system clock via PGOOD pin to eliminate beat frequencies. Use Value: External clock sync (0.9–1.3× fOSC) enables deterministic EMI placement while retaining current-mode stability. | Use Scenario: Configurable 1.0V–1.8V core rail for Xilinx Spartan-6 FPGAs in ruggedized industrial controllers. IC Role / Device Role / Timing Role: Robust controller with wide 3.5–36V input range, overvoltage crowbar protection, and latched short-circuit shutdown. Use Value: Internal 5.2V LDO (INTVCC) and EXTVCC switchover allow self-biasing from FPGA I/O rail, reducing external bias complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS54620RGYR | Integrated FETs (30V, 6A), fixed 500kHz freq, no EXTVCC option, lower IQ (12µA shutdown) | Targeted at space-constrained mid-power apps; lacks programmable current limit and OPTI-LOOP™ flexibility | Choose for simplified layout where integrated MOSFETs and smaller footprint outweigh need for external RSENSE tuning and wide VIN range. |
| ISL95836IRZ | Triple-output IMVP-7 compliant controller, supports VR12.5/VR12.6, higher integration (DAC, telemetry), 3.3–24V VIN | Designed specifically for modern CPU/GPU VRMs with digital interface; not drop-in for discrete MOSFET designs | Choose only for next-gen mobile processor platforms requiring IMVP-7 compliance and digital voltage identification. |
Compared with TPS54620RGYR and ISL95836IRZ, the LTC1735CGN-1 provides superior design flexibility for discrete high-current CPU core supplies through user-programmable current sensing, wide input range (3.5–36V), and OPTI-LOOP™ adaptive compensation - making it ideal for legacy and custom mobile/embedded power architectures where external MOSFET selection and thermal partitioning are critical.
Availability
LTC1735CGN-1 is available at Aetrix Electronics and suitable for notebook computers, wireless modems, and industrial FPGA power systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC1735CGN-1 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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1735CGN-1 belongs to Linear's legacy high-efficiency DC/DC controller product line, designed specifically for demanding CPU core power applications in mobile and embedded systems where precision regulation, transient response, and thermal resilience are essential.
FAQ
What is the maximum input voltage rating for the LTC1735CGN-1?
The LTC1735CGN-1 has an absolute maximum input voltage rating of 36V on the VIN pin. Continuous operation is specified from 3.5V to 30V, with transient tolerance up to 36V. Exceeding 36V risks permanent damage to internal circuitry, especially the INTVCC LDO and gate drivers. The device also specifies absolute maximum ratings for BOOST (42V) and SW (36V), reflecting its synchronous buck topology with floating high-side drive requirements.
How does the LTC1735CGN-1 implement current limiting and short-circuit protection?
The LTC1735CGN-1 uses dual-stage current protection: (1) cycle-by-cycle peak current limiting via SENSE+/SENSE– pins with programmable threshold (60–85 mV), and (2) foldback current limiting activated when VOSENSE drops below 0.6V - clamping ITH to reduce peak current to ~25% of maximum. For sustained short circuits, the RUN/SS capacitor (CSS) discharges to trigger latched shutdown after a user-defined timeout, which can be defeated by injecting >5µA into RUN/SS.
Can the LTC1735CGN-1 operate without an external bootstrap diode?
No - the LTC1735CGN-1 requires an external Schottky diode (e.g., CMDSH-3) between INTVCC and BOOST to recharge the bootstrap capacitor during low-side conduction. This diode enables the floating top-gate driver (TG) to maintain sufficient gate-source voltage for the high-side N-MOSFET. Omitting it causes loss of high-side drive, unregulated output, and potential shoot-through failure. The datasheet explicitly specifies this diode in all application schematics and functional diagrams.
What is the purpose of the EXTVCC pin on the LTC1735CGN-1?
The EXTVCC pin on the LTC1735CGN-1 allows external biasing of the internal 5.2V LDO (INTVCC). When EXTVCC exceeds 4.7V, the internal regulator shuts off and an internal switch connects EXTVCC directly to INTVCC - enabling efficient self-supply from the converter's own output or another clean rail. This reduces power loss and heat generation compared to deriving INTVCC solely from VIN, especially at high input voltages.
Does the LTC1735CGN-1 support remote voltage sensing, and how is it implemented?
Yes - the LTC1735CGN-1 supports true remote output voltage sensing via the VOSENSE pin, which accepts feedback from a Kelvin-connected resistive divider placed directly at the load. This compensates for IR drop across PCB traces and connectors, ensuring accurate regulation at the point-of-load. The VOSENSE pin has high impedance (±4 nA input current) and references the internal 0.8V bandgap, enabling precise closed-loop control independent of routing losses.
LTC1735CGN-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (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):
- 3.5V ~ 30V
- Frequency - Switching:
- 300kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power Good, Soft Start
- Operating Temperature:
- 0°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC1735CGN-1#TRPBF FAQ
1.How can I place an order for LTC1735CGN-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735CGN-1#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 LTC1735CGN-1#TRPBF reliable?
The price and inventory of LTC1735CGN-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735CGN-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1735CGN-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1735CGN-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1735CGN-1#TRPBF?
LTC1735CGN-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1735CGN-1#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 LTC1735CGN-1#TRPBF?
For technical support, including LTC1735CGN-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735CGN-1#TRPBF requirements.
6.How does Aetrix verify that LTC1735CGN-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1735CGN-1#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 LTC1735CGN-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1735CGN-1#TRPBF?
All LTC1735CGN-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735CGN-1#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 LTC1735CGN-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC1735CGN-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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