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Analog Devices Inc. LTC1735IF#TRPBF
- Part No.:
- LTC1735IF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LTC1735IF#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,000
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Product details
Overview
LTC1735IF#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 LTC1735IF#TRPBF datasheet, LTC1735IF#TRPBF pinout, LTC1735IF#TRPBF application, or LTC1735IF#TRPBF equivalent, key selection criteria include programmable forced-continuous mode via FCB pin, remote sense capability, 0.8V precision reference compatible with microprocessor core supplies, and 20-Lead TSSOP package with PGOOD output.
Technical Context
The LTC1735IF#TRPBF implements a constant-frequency, current-mode control architecture with dual N-channel gate drivers (TG, BG), internal 5.2V INTVCC regulator, and external oscillator capacitor (COSC) setting frequency from 265kHz to 335kHz (typ). Its error amplifier (EA) drives ITH to regulate peak inductor current, while VOSENSE feedback maintains 0.8V reference with ±1% accuracy over temperature and line/load.
Burst Mode™ operation-enabled when FCB ≥ 0.8V-disables switching until output droop triggers resumption, achieving >85% efficiency at 10mA load. Forced continuous mode (FCB ≤ 0.76V) eliminates low-frequency ripple but increases quiescent current; synchronization (FCB clocked 0.9–1.3× fOSC) enables noise-sensitive applications requiring constant-frequency operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 30V operating, 36V absolute max - supports wide industrial and telecom supply rails. |
| Output Voltage Range | 0.8V to 6V - set by external resistor divider; 0.8V reference enables modern low-voltage microprocessor core supplies. |
| Output Voltage Accuracy | ±1% over temperature and line/load - ensures stable regulation for sensitive digital loads. |
| Oscillator Frequency | 265–335kHz (typ, COSC = 47pF) - externally programmable for efficiency/size trade-off; synchronizable up to 500kHz. |
| Current Sense Threshold | 60–85mV (ΔVSENSE(MAX)) - sets peak inductor current limit; foldback reduces trip point under short-circuit conditions. |
| Shutdown Quiescent Current | <25µA (IQ) - enables ultra-low-power system standby states without compromising startup reliability. |
| Duty Cycle Max | 98–99.4% - supports very low dropout operation (e.g., 5V→4.9V), critical for high-VIN, low-VOUT conversion. |
Pinout & Package
Package: 20-Lead Plastic TSSOP (F package), JEDEC MO-153 compliant, 0.65mm pitch, exposed pad for thermal enhancement. Pin count and layout match LTC1735F series; NC pins are unconnected and must be left floating or grounded per layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19, 20, 11 | NC | No-connect pins; electrically isolated and thermally inactive - no routing or soldering required. |
| 2 (COSC) | Oscillator Timing Input | Connects external capacitor to ground; sets switching frequency and enables synchronization via FCB pin. |
| 3 (RUN/SS) | Run Control / Soft-Start | Capacitor-to-ground sets soft-start ramp time (~1.25s/µF); <1.5V forces shutdown with full circuit disable. |
| 4 (ITH) | Error Amplifier Compensation | Controls peak inductor current; voltage range 0–2.4V directly modulates current comparator threshold. |
| 5 (FCB) | Forced Continuous / Sync Input | Ground = forced continuous; INTVCC = Burst Mode; external clock = synchronized constant-frequency operation. |
| 6 (SGND) | Small-Signal Ground | Reference node for COSC, CSS, feedback divider, and compensation network - single-point tie to PGND required. |
| 7 (VOSENSE) | Feedback Input | Receives divided output voltage; servo loop maintains 0.8V at this pin for precise regulation. |
| 8 (PGOOD) | Power-Good Output | Open-drain signal asserted low when VOSENSE deviates >±7.5% from 0.8V - enables system sequencing and fault detection. |
| 9 (SENSE–) | Current Sense Negative | Inverting input of current comparator; referenced to SGND; used with SENSE+ to detect RSENSE voltage drop. |
| 10 (SENSE+) | Current Sense Positive | Non-inverting input of current comparator; common-mode range extends to 1.1×INTVCC - supports high-side sensing. |
| 12 (TG) | Top Gate Driver Output | Drives gate of high-side N-MOSFET; floating driver referenced to SW node; 3A peak current capability. |
| 13 (BOOST) | Bootstrap Supply | Return for external bootstrap capacitor; voltage swing = INTVCC superimposed on SW - enables high-side drive. |
| 14 (SW) | Switch Node | Connection to inductor and bootstrap diode; voltage swings from ~–0.4V (Schottky drop) to VIN - high dV/dt node. |
| 15 (VIN) | Main Power Input | Primary supply rail; decoupling capacitor must be placed adjacent to pin; supports 4V–30V operation. |
| 16 (INTVCC) | Internal Regulator Output | 5.2V regulated supply for logic and drivers; requires 1µF ceramic + ≥4.7µF tantalum decoupling at pin. |
| 17 (BG) | Bottom Gate Driver Output | Drives gate of low-side N-MOSFET; rail-to-rail swing from PGND to INTVCC; 3A peak current capability. |
| 18 (PGND) | Power Ground | High-current return path for BG, SW, and CIN negative terminal - separate from SGND to minimize noise coupling. |
| 19 (EXTVCC) | External VCC Input | Optional 4.7–7V supply to power INTVCC; bypasses internal LDO for higher efficiency and gate drive headroom. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ Operation | Enables >85% efficiency at 10mA load by disabling switching until output droop triggers burst - ideal for battery-powered systems. |
| OPTI-LOOP™ Compensation | Allows stable loop response across wide range of output capacitor ESR and capacitance values - simplifies design with ceramic or polymer capacitors. |
| Remote Output Voltage Sense (VOSENSE) | Compensates for IR drop in PCB traces and connectors - maintains ±1% regulation at load point, not at IC pins. |
| Programmable Forced Continuous Mode | FCB pin control eliminates low-frequency ripple and enables secondary winding regulation - critical for multi-output flyback-derived topologies. |
| Integrated Overvoltage Crowbar Protection | Clamps output during transient overshoot (>±7.5%) by turning off TG and enabling BG - prevents damage to downstream logic. |
| Latched Short-Circuit Shutdown | Uses RUN/SS capacitor (CSS) as timeout timer; shuts down after sustained overcurrent and requires pin recycle - protects MOSFETs and inductor. |
Applications
| Industrial DC Power Distribution | Notebook Computer Core Supply |
|---|---|
|
Use Scenario: Centralized 24V bus powering multiple 3.3V/5V/1.2V point-of-load converters in PLC backplanes or motor drive control modules. IC Role / Device Role / Timing Role: Primary step-down controller regulating intermediate bus voltage with remote sense to compensate for long trace drops. Use Value: 99% duty cycle capability enables 24V→23.5V conversion; PGOOD output coordinates sequencing with FPGA and ADC power domains. |
Use Scenario: Main CPU core voltage regulator in ultraportable notebooks requiring tight regulation, low noise, and dynamic VID-like adjustment. IC Role / Device Role / Timing Role: Synchronous buck controller delivering 1.2V @ 9A with ±1% accuracy and Burst Mode™ for idle-state efficiency. Use Value: 0.8V reference and remote sensing maintain regulation at processor die; OPTI-LOOP™ accommodates low-ESR polymer output capacitors. |
| Wireless Base Station RF Power Amplifier Bias | Automotive Infotainment System PMIC Sub-Regulator |
|
Use Scenario: Bias supply for GaN RF power amplifiers requiring clean, adjustable 5V–6V at 3A with minimal conducted EMI. IC Role / Device Role / Timing Role: Fixed-frequency synchronous controller operating in forced continuous mode to eliminate sub-harmonic noise in RF bands. Use Value: FCB pin grounding disables Burst Mode™; 335kHz max frequency avoids AM radio band; PGOOD confirms stable bias before PA enable. |
Use Scenario: Secondary 1.8V/3.3V regulator in automotive infotainment head unit, powered from main 5V rail, requiring AEC-Q200-compliant operation. IC Role / Device Role / Timing Role: High-efficiency buck controller supporting wide input (4.5V–18V) and cold-crank (4V) conditions with undervoltage lockout. Use Value: 4V min VIN and UVLO at 3.5V ensure operation during engine cranking; latched shutdown protects against sustained load dump faults. |
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 | Integrated power stage (no external MOSFETs); fixed 500kHz frequency; no Burst Mode™ or PGOOD. | Suitable for lower-current (<2A), space-constrained designs where external FETs are undesirable. | Select MP2451DT-LF-Z only if integrated FETs meet voltage/current requirements and PGOOD is unnecessary. |
| LTC3850EGN#PBF | Higher integration: includes MOSFET drivers, 5V LDO, and dual-phase capability; supports 4.5V–38V input. | Targeted at high-current (>20A), multi-phase server or telecom applications requiring tighter transient response. | Choose LTC3850EGN#PBF when phase interleaving, higher VIN, or integrated gate drivers reduce BOM count and layout complexity. |
Compared with MP2451DT-LF-Z and LTC3850EGN#PBF, the LTC1735IF#TRPBF provides unique flexibility in external MOSFET selection, Burst Mode™ efficiency optimization, and remote sensing - making it optimal for mid-power (3–10A), noise-sensitive, or thermally constrained applications where discrete FETs offer superior thermal and electrical performance.
Availability
LTC1735IF#TRPBF is available at Aetrix Electronics and suitable for industrial DC power distribution, notebook computer core supplies, wireless base station bias, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1735IF#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 computing markets.
The LTC1735IF#TRPBF belongs to Linear's legacy high-efficiency DC/DC controller product line, designed specifically for synchronous step-down regulation in portable, telecom, and industrial systems demanding precision, flexibility, and robust protection.
FAQ
What is the function of the FCB pin on the LTC1735IF#TRPBF?
The FCB pin on the LTC1735IF#TRPBF controls operating mode: grounding enables forced continuous conduction (reducing noise), connecting to INTVCC activates Burst Mode™ for light-load efficiency, and applying an external clock (0.9–1.3× fOSC) synchronizes switching. The LTC1735IF#TRPBF does not operate in Burst Mode™ when FCB is below 0.76V, and the pin must remain un-driven during shutdown (RUN/SS low).
Does the LTC1735IF#TRPBF support remote voltage sensing?
Yes, the LTC1735IF#TRPBF supports true remote output voltage sensing via dedicated VOSENSE, SENSE+, and SENSE– pins. This allows feedback to be taken directly at the load, compensating for IR drop in PCB traces and connectors. The LTC1735IF#TRPBF maintains ±1% output regulation accuracy at the remote point when properly implemented with Kelvin connections.
What protection features are integrated into the LTC1735IF#TRPBF?
The LTC1735IF#TRPBF integrates internal foldback current limiting, output overvoltage crowbar protection (triggered at >±7.5% VOSENSE deviation), latched short-circuit shutdown with user-programmable timeout via RUN/SS capacitor, and undervoltage lockout (UVLO) at 3.5V. These features protect external MOSFETs, inductors, and downstream loads without requiring external circuitry.
How does the LTC1735IF#TRPBF achieve high efficiency at light loads?
The LTC1735IF#TRPBF achieves high light-load efficiency via Burst Mode™ operation: when FCB ≥ 0.8V, the controller discontinues switching cycles until output voltage droop triggers a burst of pulses to recharge the output capacitor. This reduces average switching losses, enabling >85% efficiency at 10mA load. The LTC1735IF#TRPBF exits Burst Mode™ automatically when load increases beyond ~25% of maximum rated current.
Is the LTC1735IF#TRPBF pin-compatible with other members of the LTC1735 family?
The LTC1735IF#TRPBF is pin-compatible with the LTC1735F variants (e.g., LTC1735CF, LTC1735IF) in the 20-lead TSSOP package, sharing identical pinout, functionality, and PGOOD output. It is not pin-compatible with 16-lead SO or SSOP versions (LTC1735CS, LTC1735IS), which lack PGOOD and have different pin assignments for NC and EXTVCC functions.
LTC1735IF#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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
LTC1735IF#TRPBF FAQ
1.How can I place an order for LTC1735IF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735IF#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 LTC1735IF#TRPBF reliable?
The price and inventory of LTC1735IF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735IF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1735IF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1735IF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1735IF#TRPBF?
LTC1735IF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1735IF#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 LTC1735IF#TRPBF?
For technical support, including LTC1735IF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735IF#TRPBF requirements.
6.How does Aetrix verify that LTC1735IF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1735IF#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 LTC1735IF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1735IF#TRPBF?
All LTC1735IF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735IF#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 LTC1735IF#TRPBF part is unused and in its original packaging.
Return procedure for LTC1735IF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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