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Analog Devices Inc. LTC1735IF#PBF
- Part No.:
- LTC1735IF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LTC1735IF#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,178
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Product details
Overview
LTC1735IF#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller driving external N-channel MOSFETs in fixed-frequency current-mode operation. It delivers 0.8V to 6V output at up to 9A with ±1% output voltage accuracy, 4V–30V input range, and Burst Mode™ for high efficiency at light loads. It is used in notebook computers and DC power distribution systems requiring precise regulation and low-noise operation.
For engineers reviewing the LTC1735IF#PBF datasheet, LTC1735IF#PBF pinout, LTC1735IF#PBF application, or LTC1735IF#PBF equivalent, key selection criteria include its OPTI-LOOP™ compensation for wide output capacitor/ESR tolerance, forced continuous mode control via FCB pin, programmable soft-start, remote sense capability, and 20-lead TSSOP package with PGOOD output.
Technical Context
The LTC1735IF#PBF implements a constant-frequency, current-mode control architecture with dual N-channel MOSFET gate drivers (TG and BG), an internal 5.2V LDO (INTVCC), and a precision 0.8V reference with ±1% accuracy over temperature. Its error amplifier (EA) drives ITH to regulate peak inductor current, while foldback current limiting activates when VOSENSE drops below 0.6V.
Burst Mode™ operation-enabled by pulling FCB ≥0.8V-is disabled under external synchronization or forced continuous mode (FCB ≤0.76V), enabling cycle-skipping or noise-sensitive constant-frequency operation. The device supports synchronization up to 500kHz and includes undervoltage lockout (UVLO = 3.5V), overvoltage crowbar protection (VOVL = 0.84–0.88V), and latched short-circuit shutdown with defeat option.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 30V operating; 36V absolute max - supports wide industrial and computing supply rails. |
| Output Voltage Range | 0.8V to 6V - set via external resistor divider; compatible with sub-1V microprocessor cores. |
| Output Voltage Accuracy | ±1% over full temperature range - ensures stable regulation for sensitive digital loads. |
| Switching Frequency | Programmable 265–335 kHz (COSC = 43 pF); synchronizable up to 500 kHz - balances efficiency vs. size. |
| Peak Gate Drive Current | 3A per driver (TG/BG) - sufficient to drive high-side and low-side N-MOSFETs with fast transitions. |
| Quiescent Current | 25 µA in shutdown - enables ultra-low-power system standby modes. |
| Duty Cycle Max | 99.4% - supports very low dropout operation near VIN ≈ VOUT. |
| PGOOD Threshold | ±7.5% window around setpoint - provides reliable power-good signaling for sequencing. |
Pinout & Package
The LTC1735IF#PBF is housed in a 20-lead plastic TSSOP package (JEDEC MO-153, 4.4 mm × 6.5 mm), thermally enhanced for high-current DC/DC applications. Pin 1 is marked with a dot; exposed pad (EP) is electrically connected to PGND and must be soldered for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (NC) | No Connect | Reserved; no internal connection - must be left floating or grounded per layout guidelines. |
| 2 (COSC) | Oscillator Timing Input | Connects to external capacitor to set switching frequency; determines timing accuracy and sync range. |
| 3 (RUN/SS) | Run Control / Soft-Start | Capacitor-to-ground sets soft-start ramp time (~1.25 s/µF); <1.5V disables all functions including INTVCC. |
| 4 (ITH) | Error Amplifier Compensation | Controls peak inductor current; voltage range 0–2.4V directly modulates current limit threshold. |
| 5 (FCB) | Forced Continuous / Sync Input | Enables Burst Mode (≥0.8V), forced continuous (≤0.76V), or external clock sync (1.3–0.3V swing). |
| 6 (SGND) | Small-Signal Ground | Reference for COSC, CSS, feedback divider, and compensation network - single-point tie to PGND required. |
| 7 (VOSENSE) | Feedback Voltage Input | Receives divided output voltage; servo loop maintains 0.8V reference with ±1% accuracy. |
| 8 (PGOOD) | Power-Good Output | Open-drain signal pulled low when VOSENSE deviates >±7.5% - used for system sequencing and fault reporting. |
| 9 (SENSE–) | Current Sense Negative Input | Inputs low-side of RSENSE; common-mode range extends to SGND - enables accurate current sensing down to 0V. |
| 10 (SENSE+) | Current Sense Positive Input | Inputs high-side of RSENSE; built-in offset with SENSE– sets trip threshold at 60–85 mV across RSENSE. |
| 11 (NC) | No Connect | Reserved; no internal connection - must be left floating or grounded per layout guidelines. |
| 12 (TG) | Top Gate Driver Output | Drives high-side N-MOSFET gate with 3A peak; floating driver referenced to SW node. |
| 13 (BOOST) | Bootstrap Supply | Return for external bootstrap capacitor; voltage swings from (VIN + INTVCC) down to diode-drop below INTVCC. |
| 14 (SW) | Switch Node | Connects to inductor and bootstrap capacitor; voltage swings from ground to VIN - critical for EMI layout. |
| 15 (VIN) | Main Input Supply | Primary power input (4–30V); requires local 4.7 µF tantalum + 1 µF ceramic decoupling at pin. |
| 16 (INTVCC) | Internal Regulator Output | 5.2V regulated supply for logic and drivers; powered from VIN or EXTVCC if >4.7V - decouple with 1 µF ceramic + 4.7 µF tantalum. |
| 17 (BG) | Bottom Gate Driver Output | Drives low-side N-MOSFET gate with 3A peak; referenced to PGND - enables synchronous rectification. |
| 18 (PGND) | Power Ground | Return for bottom MOSFET source, Schottky cathode, and CIN negative - separate from SGND to minimize noise coupling. |
| 19 (EXTVCC) | External VCC Input | Optional 4.7–7V supply to bypass internal LDO and improve gate drive efficiency - must not exceed VIN. |
| 20 (NC) | No Connect | Reserved; no internal connection - must be left floating or grounded per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ Compensation | Minimizes required output capacitance and relaxes ESR constraints - simplifies design across diverse capacitor types. |
| Forced Continuous Mode Control | Eliminates Burst Mode noise via FCB pin - essential for RF-sensitive or audio applications requiring constant-frequency operation. |
| Remote Output Voltage Sensing | Compensates for PCB trace IR drop - maintains ±1% regulation accuracy at load point, not at IC pins. |
| Programmable Soft-Start | Prevents inrush current with external CSS capacitor - enables controlled power-up and supply sequencing. |
| Integrated Overvoltage Crowbar | Shuts down top MOSFET and turns on bottom MOSFET during >±7.5% overvoltage - protects downstream loads from transient damage. |
| Latched Short-Circuit Shutdown | Disables operation after sustained overcurrent; defeatable via RUN/SS current injection - prevents thermal runaway without manual reset. |
Applications
| Portable Computing Power | Wireless Baseband Power |
|---|---|
|
Use Scenario: Powering CPU core voltage (1.0–1.6V) in ultraportable notebooks with dynamic load steps up to 9A. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating main processor rail with remote sense and PGOOD sequencing. Use Value: ±1% output accuracy and OPTI-LOOP™ ensure stable core voltage under rapid load transients; Burst Mode™ extends battery life during idle. |
Use Scenario: Generating 3.3V/5A supply for LTE/Wi-Fi baseband ICs in smartphones with strict EMI limits. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller with forced continuous mode (FCB = GND) to suppress switching noise in RF bands. Use Value: Constant 300 kHz operation avoids interference with cellular receive bands; 99.4% duty cycle supports low-dropout operation during brownout. |
| Industrial DC Distribution | Embedded System Auxiliary Rail |
|
Use Scenario: Converting 24V bus to 5V/6A for PLC I/O modules requiring high reliability and wide input range. IC Role / Device Role / Timing Role: Robust synchronous buck controller with UVLO (3.5V), overvoltage crowbar, and latched shutdown for fault containment. Use Value: 4–30V input range accommodates unregulated industrial supplies; PGOOD output enables watchdog-triggered system reset on rail failure. |
Use Scenario: Providing isolated 1.8V/3A auxiliary rail for FPGA configuration and memory interface in edge AI gateways. IC Role / Device Role / Timing Role: Programmable buck controller with external synchronization (FCB pin) to align switching with system clock domain. Use Value: Synchronization to 25 MHz system clock eliminates beat frequencies; remote sense compensates for 50 mΩ board trace resistance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2451DT-LF-Z | Fixed 500 kHz frequency; no Burst Mode™; integrated MOSFETs (2A max); no PGOOD or remote sense. | Suitable for space-constrained, lower-current (<2A) applications where simplicity outweighs efficiency optimization. | Select MP2451DT-LF-Z only for cost-sensitive, low-power designs lacking need for light-load efficiency or sequencing signals. |
| LTC3850EGN#PBF | Higher current capability (15A+); dual-phase support; wider VIN (4–38V); includes phase-lock loop for multi-phase sync. | Targeted at high-current server or telecom power supplies requiring interleaved operation and tighter ripple control. | Choose LTC3850EGN#PBF when scaling beyond 9A or requiring multi-phase coordination - not a drop-in replacement. |
Compared with MP2451DT-LF-Z, the LTC1735IF#PBF offers superior light-load efficiency via Burst Mode™ and robust system integration features (PGOOD, remote sense, programmable soft-start); compared with LTC3850EGN#PBF, it provides a more compact, cost-optimized solution for single-phase 9A applications without multi-phase complexity.
Availability
LTC1735IF#PBF is available at Aetrix Electronics and suitable for notebook computing, wireless infrastructure, and industrial DC distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance.
Supply support for LTC1735IF#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 computing markets.
The LTC1735IF#PBF belongs to Linear's high-efficiency synchronous buck controller product line, designed specifically for portable and power-sensitive applications demanding precision regulation, flexible frequency control, and robust protection features.
FAQ
What is the maximum supported switching frequency for LTC1735IF#PBF?
The LTC1735IF#PBF supports synchronization up to 500 kHz, with nominal free-running frequency set by COSC (e.g., 300 kHz with 43 pF). The internal oscillator can lock to external clocks between 90% and 130% of its nominal frequency. Exceeding 500 kHz risks slope compensation instability and is not recommended per datasheet guidance.
Does LTC1735IF#PBF include an integrated power MOSFET?
No, the LTC1735IF#PBF is a controller-only IC and requires external N-channel MOSFETs for both high-side and low-side switching. It provides dual 3A gate drivers (TG and BG) optimized for discrete FETs - unlike monolithic regulators, this enables scalable current handling and thermal management flexibility in the LTC1735IF#PBF design.
What is the function of the PGOOD pin on LTC1735IF#PBF?
The PGOOD pin on LTC1735IF#PBF is an open-drain output that asserts low when the VOSENSE voltage deviates by more than ±7.5% from the 0.8V reference. This signal enables safe power sequencing, system reset triggering, and fault monitoring in host systems - a feature exclusive to the F-package variants like LTC1735IF#PBF.
How does the FCB pin affect operating mode in LTC1735IF#PBF?
The FCB pin on LTC1735IF#PBF selects three distinct modes: ≥0.8V enables Burst Mode™ for highest light-load efficiency; ≤0.76V forces continuous conduction to eliminate switching noise; and AC-coupled external clocking (1.3–0.3V swing) enables synchronized constant-frequency operation. Mode selection is voltage-threshold-based and fully documented in the LTC1735IF#PBF datasheet.
What package type is used for LTC1735IF#PBF?
The LTC1735IF#PBF uses a 20-lead plastic TSSOP package (JEDEC MO-153) with an exposed thermal pad connected to PGND. This package provides improved thermal performance over 16-lead SO/SSOP variants and supports the PGOOD functionality unique to the F-grade version of the LTC1735IF#PBF.
LTC1735IF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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):
- 4V ~ 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
LTC1735IF#PBF FAQ
1.How can I place an order for LTC1735IF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735IF#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 LTC1735IF#PBF reliable?
The price and inventory of LTC1735IF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735IF#PBF is usually 5 days.
3.What payment methods are accepted for LTC1735IF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1735IF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1735IF#PBF?
LTC1735IF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1735IF#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 LTC1735IF#PBF?
For technical support, including LTC1735IF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735IF#PBF requirements.
6.How does Aetrix verify that LTC1735IF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1735IF#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 LTC1735IF#PBF meets industry standards.
7.What is the process for return or replacement of LTC1735IF#PBF?
All LTC1735IF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735IF#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 LTC1735IF#PBF part is unused and in its original packaging.
Return procedure for LTC1735IF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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