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Analog Devices Inc. LTC1265CS-3.3#PBF
- Part No.:
- LTC1265CS-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1265CS-3.3#PBF.pdf
- Description:
- IC REG BUCK BOOST 3.3V 1.2A 14SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,554
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Product details
Overview
LTC1265CS-3.3#PBF from Analog Devices (formerly Linear Technology) is a monolithic step-down DC/DC converter IC with integrated 0.3Ω P-channel MOSFET switch, delivering up to 1.2A output current at a fixed 3.3V output voltage. It operates from 5.4V to 12V input, achieves up to 95% efficiency, and features Burst Mode™ operation for ultra-low 160µA quiescent current at light loads - ideal for battery-powered portable instruments and cellular telephones.
For engineers reviewing the LTC1265CS-3.3#PBF datasheet, LTC1265CS-3.3#PBF pinout, LTC1265CS-3.3#PBF application, or LTC1265CS-3.3#PBF equivalent, key selection criteria include its fixed 3.3V output, internal current-sense threshold (25mV–180mV), low-battery detection capability, 14-pin SO package, and compatibility with standard 33µH inductors and 0.1Ω sense resistors.
Technical Context
The LTC1265CS-3.3#PBF uses constant off-time current-mode control with external CT capacitor timing, enabling frequency adjustment based on (VIN – VOUT). Its internal resistive divider sets VOUT = 3.3V via SENSE– (Pin 7), eliminating need for external feedback resistors. The device automatically transitions between continuous conduction mode and Burst Mode™ based on load demand.
Burst Mode™ operation reduces gate charge losses by disabling switching until output voltage droops below hysteresis threshold, achieving 160µA sleep current. Short-circuit protection is implemented via peak inductor current limiting (150mV/RSENSE), while low-dropout operation enables 100% duty cycle when VIN approaches VOUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3.3% (3.22V–3.40V) at 800mA load - ensures stable logic supply for 3.3V microcontrollers and peripherals. |
| Input Voltage Range | 5.4V to 12V - supports single-cell Li-ion (fully charged) and multi-cell alkaline/NiMH battery inputs. |
| Max Output Current | 1.2A continuous - sufficient for powering baseband processors, RF modules, and sensor subsystems. |
| Switch RDS(ON) | 0.3Ω typical at VIN = 10V - minimizes conduction loss and thermal rise under full load. |
| Quiescent Current | 160µA in sleep mode - extends battery life in standby or intermittent-use applications. |
| Shutdown Current | 5µA typical - enables true system-level power gating during deep sleep. |
| Low-Battery Threshold | 1.15V to 1.35V trip point - configurable via external resistor divider on LBIN (Pin 4) for accurate battery monitoring. |
| Efficiency | Up to 95% at 800mA, VIN = 9V - reduces heat generation and improves runtime in compact enclosures. |
Pinout & Package
Package: 14-lead plastic SO (Small Outline), 150 mil width, JEDEC MS-012AC, θJA = 110°C/W. RoHS-compliant, lead-free (PbF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWR VIN (Pins 1, 13) | Power MOSFET driver supply | Must be tied together and decoupled locally to PGND; supplies gate drive for internal P-MOSFET. |
| VIN (Pin 2) | Main control circuit supply | Provides bias for internal reference, comparators, and logic - separate from power switch supply. |
| LBOUT (Pin 3) | Open-drain low-battery alert | Sinks current when LBIN falls below 1.25V; high-impedance in shutdown - interfaces directly to µC GPIO. |
| LBIN (Pin 4) | Inverting input of low-battery comparator | Accepts voltage divider from VIN; comparator trips at 1.25V reference - enables customizable battery cutoff. |
| CT (Pin 5) | Off-time timing capacitor node | External capacitor (e.g., 130pF) sets switch off time; frequency varies with (VIN – VOUT) - enables adaptive switching. |
| ITH (Pin 6) | Current comparator threshold control | Voltage here modulates current limit threshold - used internally for load regulation and Burst Mode transition. |
| SENSE– (Pin 7) | Current comparator negative input / VOUT divider tap | Internally connected to 3.3V divider network - no external resistor needed for fixed-output version. |
| SENSE+ (Pin 8) | Current comparator positive input | Connects across RSENSE; 25mV–180mV threshold range sets peak inductor current - defines overcurrent protection level. |
| N/C (Pin 9) | No connect | Not bonded or used in LTC1265CS-3.3#PBF - reserved for adjustable-version feedback (LTC1265). |
| SHDN (Pin 10) | Active-high micropower shutdown | Logic HIGH (>1.2V) disables switching and reduces IQ to 5µA - enables system-level power sequencing. |
| SGND (Pin 11) | Small-signal ground | Must route separately to COUT (–) terminal - prevents noise coupling into feedback and sensing paths. |
| PGND (Pin 12) | Power ground | Return for CIN (–), Schottky anode, and internal switch - requires low-inductance connection to minimize EMI. |
| SW (Pin 14) | Drain of internal P-channel MOSFET | Switching node connecting to inductor and Schottky cathode - critical for layout; must minimize loop area. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Reduces quiescent current to 160µA at light loads while maintaining tight output regulation - eliminates need for external enable sequencing in battery systems. |
| Internal 0.3Ω P-MOSFET switch | Enables 1.2A output without external FET or driver - simplifies BOM and PCB layout while minimizing conduction loss at high duty cycles. |
| Fixed 3.3V output with internal divider | Eliminates external feedback resistors and associated layout sensitivity - improves production yield and long-term stability vs. adjustable versions. |
| Low-battery detector with open-drain output | Provides system-level battery health monitoring using only two external resistors - enables graceful shutdown before brownout. |
| 100% duty cycle low-dropout operation | Maintains regulation down to VIN ≈ VOUT + 0.2V - maximizes usable battery capacity in single-cell Li-ion applications. |
| Short-circuit protection with automatic recovery | Limits peak inductor current to 150mV/RSENSE and extends off-time during fault - protects downstream components without latch-up or manual reset. |
Applications
| Portable Instruments | Cellular Telephones |
|---|---|
Use Scenario: Handheld multimeter or data logger powered by two AA alkaline cells (3.0V–3.6V nominal) with boost converter feeding LTC1265CS-3.3#PBF. IC Role / Device Role / Timing Role: Primary 3.3V system regulator supplying MCU, display driver, and ADC reference - maintains stable rail during varying measurement loads. Use Value: 95% efficiency at 250mA extends battery life >30% vs. linear regulators; Burst Mode™ preserves 160µA sleep current during idle intervals. | Use Scenario: Baseband processor power rail in GSM handset with Li-ion battery (3.4V–4.2V) and dynamic load profile (burst TX/RX, idle). IC Role / Device Role / Timing Role: Main 3.3V core supply for digital baseband IC - handles rapid load transients via current-mode control and low 160µA quiescent draw. Use Value: Internal 0.3Ω switch and 1.2A rating support peak TX currents; low-battery detection (Pin 4) triggers graceful power-down before cell depletion. |
| Memory Backup Supply | Distributed Power Systems |
Use Scenario: SRAM or real-time clock backup in industrial controller where main 5V rail may fail unexpectedly. IC Role / Device Role / Timing Role: Standby 3.3V regulator powered from supercapacitor or coin cell - activated only during main rail dropout. Use Value: 5µA shutdown current preserves backup energy for >1 year; 100% duty cycle operation sustains VOUT down to VIN = 3.35V. | Use Scenario: Local 3.3V point-of-load regulator on a 12V backplane in telecom shelf, driving FPGA I/O banks and SerDes termination. IC Role / Device Role / Timing Role: High-efficiency DC/DC stage converting 12V to 3.3V - placed near load to minimize IR drop and noise coupling. Use Value: 14-pin SO package allows dense placement; 95% efficiency reduces localized heating in air-cooled chassis. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1935ES5-3.3#TRMPBF | 5-pin SOT-23, 1.25A, fixed 3.3V, 2.5V–16V input, 100µA quiescent current - smaller footprint but no low-battery detection or CT programmability. | Lacks LBIN/LBOUT pins and CT-based frequency tuning - unsuitable where battery monitoring or EMI-controlled switching is required. | Select LT1935ES5-3.3#TRMPBF only when board space is constrained and low-battery alert is handled externally. |
| TPS62130ARGTR | 16-pin QFN, 3A, adjustable/fixed 3.3V, 3V–17V input, 17µA quiescent current, I²C programmable - higher current, lower IQ, but requires external compensation and lacks integrated low-battery comparator. | Supports higher output current and digital interface, but adds complexity and cost - not drop-in compatible due to different pinout, package, and feature set. | Choose TPS62130ARGTR for scalable designs needing >1.2A or programmable features; LTC1265CS-3.3#PBF remains optimal for cost-sensitive, analog-monitored 1.2A applications. |
Compared with LT1935ES5-3.3#TRMPBF and TPS62130ARGTR, the LTC1265CS-3.3#PBF uniquely integrates low-battery detection, Burst Mode™ efficiency optimization, and robust 1.2A capability in a mature, widely qualified SO-14 package - making it preferred for legacy-reliable, analog-centric portable power designs.
Availability
LTC1265CS-3.3#PBF is available at Aetrix Electronics and suitable for portable instruments, cellular telephones, and memory backup supply applications requiring stable component supply, long-lifecycle availability, and proven field reliability in battery-operated systems.
Supply support for LTC1265CS-3.3#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through acquisition of Linear Technology in 2017.
The LTC1265 family was designed by Linear Technology specifically for high-efficiency, low-quiescent-current step-down conversion in portable and battery-critical applications - emphasizing simplicity, reliability, and analog intelligence over digital configurability.
FAQ
What is the maximum input voltage rating for the LTC1265CS-3.3#PBF?
The LTC1265CS-3.3#PBF has an absolute maximum input voltage rating of 13V on Pins 1, 2, and 13. Continuous operation is specified from 5.4V to 12V. Exceeding 13V risks permanent damage due to internal junction breakdown - always ensure transient suppression if used with unregulated sources like automotive batteries or flyback outputs.
Does the LTC1265CS-3.3#PBF require external feedback resistors to set its output voltage?
No. The LTC1265CS-3.3#PBF is the fixed 3.3V version and incorporates an internal resistive divider connected to SENSE– (Pin 7). Unlike the adjustable LTC1265, Pin 9 (VFB) is NC, and no external resistors are needed - reducing component count and improving long-term output accuracy.
How does the low-battery detection function work on the LTC1265CS-3.3#PBF?
The LTC1265CS-3.3#PBF uses LBIN (Pin 4) as the inverting input to an internal 1.25V reference comparator. An external resistor divider from VIN to ground sets the trip point (e.g., 3.0V → 1.25V at LBIN). When voltage at LBIN drops below 1.25V, LBOUT (Pin 3) pulls low - providing a direct interface to microcontroller interrupt or reset logic.
What is the purpose of the CT pin (Pin 5) on the LTC1265CS-3.3#PBF?
The CT pin (Pin 5) connects to an external capacitor that sets the switch off time in the LTC1265CS-3.3#PBF's constant off-time architecture. With CT = 130pF, typical operating frequency is ~700kHz at VIN = 9V, VOUT = 3.3V. Frequency decreases as (VIN – VOUT) shrinks - preventing audible noise near dropout while maintaining control loop stability.
Can the LTC1265CS-3.3#PBF operate in 100% duty cycle mode?
Yes. The LTC1265CS-3.3#PBF supports true low-dropout operation with 100% duty cycle when VIN approaches VOUT. In this mode, the internal P-channel MOSFET remains fully enhanced, minimizing dropout voltage to <200mV at 1.2A - extending usable battery life in single-cell Li-ion and multi-cell alkaline systems.
LTC1265CS-3.3#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Buck-Boost, SEPIC
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 13V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.2A (Switch)
- Frequency - Switching:
- Up to 700kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SO
LTC1265CS-3.3#PBF FAQ
1.How can I place an order for LTC1265CS-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1265CS-3.3#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 LTC1265CS-3.3#PBF reliable?
The price and inventory of LTC1265CS-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1265CS-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LTC1265CS-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1265CS-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1265CS-3.3#PBF?
LTC1265CS-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1265CS-3.3#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 LTC1265CS-3.3#PBF?
For technical support, including LTC1265CS-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1265CS-3.3#PBF requirements.
6.How does Aetrix verify that LTC1265CS-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1265CS-3.3#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 LTC1265CS-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LTC1265CS-3.3#PBF?
All LTC1265CS-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1265CS-3.3#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 LTC1265CS-3.3#PBF part is unused and in its original packaging.
Return procedure for LTC1265CS-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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