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Analog Devices Inc. LTC1735CF#TRPBF
- Part No.:
- LTC1735CF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LTC1735CF#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,425
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Product details
Overview
LTC1735CF#TRPBF 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, supports 4V–30V input, features ±1% output voltage accuracy, OPTI-LOOP™ compensation, and Burst Mode™ for high efficiency at light loads.
For engineers reviewing the LTC1735CF#TRPBF datasheet, LTC1735CF#TRPBF pinout, LTC1735CF#TRPBF application, or LTC1735CF#TRPBF equivalent, key selection criteria include forced continuous mode control via FCB pin, remote sense capability, programmable soft-start, PGOOD output, and compatibility with wide-input industrial and portable power systems requiring stable 0.8V reference and low-noise regulation.
Technical Context
The LTC1735CF#TRPBF implements a constant-frequency, current-mode control architecture with dual N-channel gate drivers (TG/BG), internal 0.8V reference, and transconductance error amplifier (gm = 1.3 mmho). Its OPTI-LOOP™ compensation adapts transient response across broad output capacitance and ESR ranges, while Burst Mode™ enables sub-25µA quiescent current at light loads.
It integrates foldback current limiting, output overvoltage crowbar protection, latched short-circuit shutdown with defeat option, and undervoltage lockout (UVLO = 3.5V–3.9V). The FCB pin supports three operating modes: Burst Mode™ (FCB ≥ 0.8V), forced continuous (FCB = GND), and external synchronization (0.9fO–1.3fO).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 30V continuous operation; absolute max 36V - supports wide-input industrial and battery-powered systems. |
| Output Voltage Range | 0.8V to 6V - precise 0.8V reference compatible with modern microprocessors and core logic rails. |
| Output Voltage Accuracy | ±1% over temperature - ensures tight regulation for sensitive digital loads without external trimming. |
| Switching Frequency | Programmable 265–335 kHz (COSC = 43 pF); synchronizable up to 500 kHz - balances efficiency vs. size in compact designs. |
| Quiescent Current | 450 µA in normal mode; <25 µA in shutdown - enables long battery life in portable applications. |
| Duty Cycle Max | 99.4% - supports ultra-low dropout operation down to VIN – VOUT ≈ 100 mV at full load. |
| PGOOD Output | Open-drain, ±7.5% window, active-low - provides reliable power sequencing and system monitoring (LTC1735F-specific feature). |
Pinout & Package
Package: 20-lead plastic TSSOP (F package), JEDEC MO-153, 0.65 mm pitch, exposed pad for thermal enhancement. Thermal resistance θJA = 110°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| NC | No-connect | Unbonded pins (1, 11, 19, 20) - must be left floating or grounded per layout guidelines. |
| COSC | Oscillator timing capacitor | External capacitor sets switching frequency; 43 pF yields ~300 kHz - enables optimization of efficiency vs. component size. |
| RUN/SS | Run enable & soft-start control | Capacitor-to-ground sets ramp time (~1.25 s/µF); <1.5 V disables operation - enables controlled power-up and overcurrent latchoff. |
| ITH | Error amplifier output | Voltage-controlled current limit threshold (0–2.4 V range) - directly modulates peak inductor current for loop stability. |
| FCB | Forced continuous / sync input | Configures Burst Mode™ (≥0.8 V), forced continuous (GND), or external clock sync (0.9–1.3× fO) - critical for noise-sensitive or multi-rail systems. |
| SGND | Small-signal ground | Single-point return for feedback divider, COSC, CSS - isolates analog reference path from power ground noise. |
| VOSENSE | Feedback voltage input | Receives resistive divider output; ±1% accuracy referenced to 0.8 V - enables precision regulation with remote sensing. |
| PGOOD | Power-good status output | Open-drain signal asserted low when VOSENSE deviates >±7.5% - essential for FPGA/CPU power sequencing. |
| SENSE– / SENSE+ | Current sense differential inputs | Monitor RSENSE voltage drop; built-in offset sets trip threshold (60–85 mV) - enables accurate current limiting and foldback. |
| TG / BG | Top/bottom gate drivers | High-current (3 A peak) N-MOSFET drivers with 50–90 ns transition times - supports fast-switching, low-loss external FETs. |
| SW / BOOST / VIN / INTVCC / PGND / EXTVCC | Power node connections | SW connects to inductor and bootstrap cap; BOOST supplies floating top driver; EXTVCC enables efficient 5.2 V bias sourcing - defines high-efficiency power path topology. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Reduces IQ to <25 µA at light loads while maintaining regulated output - extends battery runtime in portable electronics without sacrificing regulation. |
| OPTI-LOOP™ compensation | Minimizes required output capacitance by adapting loop gain to actual COUT and ESR - simplifies design across diverse capacitor types (tantalum, polymer, ceramic). |
| Forced continuous control (FCB) | Eliminates low-frequency ripple and audible noise by disabling Burst Mode™ - critical for RF, audio, and sensor subsystems requiring clean DC. |
| Remote output voltage sensing | Compensates for PCB trace IR drop between regulator and load - ensures ±1% accuracy at point-of-load for high-current digital ICs. |
| Integrated protection suite | Includes foldback current limiting, output overvoltage crowbar, latched short-circuit shutdown, and UVLO - reduces need for external fault management circuitry. |
| PGOOD output (F-package only) | Provides system-level power validation with ±7.5% window - enables safe processor boot, FPGA configuration, and watchdog coordination. |
Applications
| Industrial Power Distribution | Portable Computing Power |
|---|---|
Use Scenario: Centralized 24V DC bus powering multiple 3.3V/1.8V/1.2V rails in PLC I/O modules and motor drives. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus voltages with remote sense and PGOOD sequencing. Use Value: 99.4% duty cycle enables operation down to 24.1V input while delivering full 9A load - minimizes bus droop impact on downstream converters. |
Use Scenario: Core voltage regulator for Intel Pentium M or AMD Mobile Athlon processors in notebook motherboards. IC Role / Device Role / Timing Role: High-accuracy, low-noise step-down controller with 0.8V reference and programmable soft-start for CPU core rail. Use Value: ±1% output accuracy and Burst Mode™ extend battery life >30% versus standard PWM controllers during idle/sleep states. |
| Wireless Baseband Power | Automotive Infotainment |
Use Scenario: Powering LTE/5G baseband SoCs (e.g., Qualcomm Snapdragon) requiring clean 1.1V/0.9V rails with fast transient response. IC Role / Device Role / Timing Role: Synchronous buck controller with OPTI-LOOP™ compensation and forced continuous mode for RF-sensitive subsystems. Use Value: FCB pin enables noise-free continuous conduction mode during data transmission bursts - prevents spectral interference with adjacent receivers. |
Use Scenario: Regulating 1.5V DDR memory supply and 3.3V MCU rail in automotive head units operating from 9–16V battery input. IC Role / Device Role / Timing Role: Wide-input buck controller with UVLO (3.5V), thermal shutdown, and PGOOD for ASIL-B compliant power domains. Use Value: 4V–30V input range and -40°C to 85°C operation ensure reliable startup and regulation during cold cranking and hot under-hood conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#TRPBF | Monolithic 3.5A buck with integrated MOSFETs; 2.8–30V input; 35ns min on-time; no PGOOD or remote sense. | Suitable for space-constrained, lower-current designs where integration outweighs flexibility. | Select LT8610EMSE#TRPBF when board area is critical and 3.5A output suffices; LTC1735CF#TRPBF preferred for >5A, remote sense, or discrete FET optimization. |
| TPS54620RGYT | 6A monolithic buck; 4.5–17V input; 0.8V ref; no Burst Mode™; 1% accuracy; integrated current sense. | Targeted at mid-range industrial and telecom supplies where fixed 17V max input is acceptable. | Choose TPS54620RGYT for simplified BOM and higher integration; LTC1735CF#TRPBF retains advantage in wide-input (>17V), ultra-low IQ, and PGOOD-enabled sequencing. |
Compared with LT8610EMSE#TRPBF and TPS54620RGYT, the LTC1735CF#TRPBF offers unique value in high-current (>6A), wide-input (up to 30V), and low-noise applications requiring remote sensing, programmable soft-start, and PGOOD - making it optimal for demanding embedded and portable power systems where flexibility and precision outweigh monolithic convenience.
Availability
LTC1735CF#TRPBF is available at Aetrix Electronics and suitable for industrial power distribution, portable computing, wireless baseband, and automotive infotainment applications requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance.
Supply support for LTC1735CF#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, Inc. (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 LTC1735 product line is designed as a flexible, high-efficiency synchronous buck controller family for demanding DC/DC conversion tasks - emphasizing precision regulation, wide input range, and robust protection in space- and power-constrained systems.
FAQ
What is the maximum output current supported by the LTC1735CF#TRPBF?
The LTC1735CF#TRPBF is a controller-not a monolithic regulator-so its output current depends on selected external MOSFETs, inductor, and layout. With appropriate FDS6680A MOSFETs and 2 µH inductor, the LTC1735CF#TRPBF supports up to 9A continuous output, as validated in the typical application circuit (Figure 1) and confirmed by thermal derating curves in the datasheet.
Does the LTC1735CF#TRPBF include an integrated power switch?
No, the LTC1735CF#TRPBF does not include integrated power switches. It is a controller IC that drives external N-channel MOSFETs (top and bottom) using dedicated TG and BG gate drive outputs. This architecture allows designers to optimize efficiency, thermal performance, and cost by selecting discrete FETs matched to specific voltage, current, and RDS(on) requirements.
What is the purpose of the PGOOD pin on the LTC1735CF#TRPBF?
The PGOOD pin on the LTC1735CF#TRPBF is an open-drain output that asserts low when the VOSENSE voltage deviates more than ±7.5% from the 0.8V reference. This signal enables safe power sequencing in complex systems-such as CPUs or FPGAs-by preventing downstream logic from initializing until the regulated output is within specification. PGOOD is exclusive to the F-package variants like LTC1735CF#TRPBF.
How does Burst Mode™ operation improve light-load efficiency in the LTC1735CF#TRPBF?
Burst Mode™ operation in the LTC1735CF#TRPBF reduces quiescent current to <25 µA by disabling both gate drivers when the ITH voltage falls below 0.5V, allowing the output capacitor to supply load current until regulation error triggers resumption. This eliminates switching losses at light loads, achieving >85% efficiency at 10 mA output-critical for battery-powered devices where standby power dominates total energy consumption.
Can the LTC1735CF#TRPBF be synchronized to an external clock source?
Yes, the LTC1735CF#TRPBF can be synchronized to an external clock applied to the FCB pin. When driven with a square wave (≥1.3V high, ≤0.3V low, ≥0.3 µs pulse width), the internal oscillator locks to frequencies between 90% and 130% of its nominal value set by COSC. This enables noise-sensitive applications to avoid beat frequencies and align switching with system clocks or other converters.
LTC1735CF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm 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):
- 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:
- 0°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
LTC1735CF#TRPBF FAQ
1.How can I place an order for LTC1735CF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735CF#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 LTC1735CF#TRPBF reliable?
The price and inventory of LTC1735CF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735CF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1735CF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1735CF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1735CF#TRPBF?
LTC1735CF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1735CF#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 LTC1735CF#TRPBF?
For technical support, including LTC1735CF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735CF#TRPBF requirements.
6.How does Aetrix verify that LTC1735CF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1735CF#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 LTC1735CF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1735CF#TRPBF?
All LTC1735CF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735CF#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 LTC1735CF#TRPBF part is unused and in its original packaging.
Return procedure for LTC1735CF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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