Analog Devices Inc. LTC1265CS-5#TRPBF

Overview

LTC1265CS-5#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic step-down DC/DC converter IC with internal 0.3Ω P-channel MOSFET switch, fixed 5V output, and Burst Mode™ operation for ultra-low quiescent current. It delivers up to 1.2A output current, achieves up to 95% efficiency at 800mA, and supports input voltage range of 5.4V to 12V. Used in battery-powered portable instruments requiring high-efficiency voltage regulation.

For engineers reviewing the LTC1265CS-5#TRPBF datasheet, LTC1265CS-5#TRPBF pinout, LTC1265CS-5#TRPBF application, or LTC1265CS-5#TRPBF equivalent, key selection criteria include its fixed 5V output, 14-pin SO package, 160µA light-load standby current, low-battery detection capability, and constant off-time control architecture enabling stable operation across wide VIN–VOUT differentials.

Technical Context

The LTC1265CS-5#TRPBF implements a current-mode, constant off-time buck controller with internal P-channel MOSFET. Its switching frequency varies inversely with input-to-output voltage differential and is set by external CT capacitor (e.g., 130pF for ~700kHz at VIN=12V, VOUT=5V). The device automatically transitions between continuous conduction mode and Burst Mode™ based on load current - Burst Mode reduces gate charge losses and cuts quiescent current to 160µA under light loads.

Output voltage is internally trimmed to 4.9V–5.2V (G-grade, –40°C to 85°C) via a precision resistive divider tied to SENSE– (Pin 7); no external feedback resistors are required. Current sensing uses a 25mV–150mV threshold across RSENSE, with peak inductor current programmable down to 25mV/RSENSE in Burst Mode and up to 150mV/RSENSE in continuous mode.

Key Specifications

Pinout & Package

Package: 14-lead plastic SO (SO-14), 150 mil width, θ_JA = 110°C/W, RoHS-compliant, tape-and-reel (#TRPBF).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter applications.

Compared with LT1934ES5-5#TRMPBF and TPS62130ARGTR, the LTC1265CS-5#TRPBF uniquely combines micropower Burst Mode operation, integrated low-battery detection, and internal P-MOSFET in a cost-optimized SO-14 package - making it optimal for long-life, feature-integrated portable equipment where component count and standby power are critical.

Availability

LTC1265CS-5#TRPBF is available at Aetrix Electronics and suitable for portable medical sensors, industrial handheld meters, wireless IoT edge nodes, and memory backup power supplies requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for LTC1265CS-5#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC1265 family was developed by Linear Technology (acquired by ADI in 2017) specifically for high-efficiency, low-quiescent-current DC/DC conversion in battery-powered portable instrumentation and distributed power systems.

FAQ

What is the output voltage tolerance of the LTC1265CS-5#TRPBF over temperature and load?

The LTC1265CS-5#TRPBF delivers a fixed 5V output with guaranteed tolerance of ±2% over full operating temperature range (–40°C to 85°C) and load current (10mA to 800mA). At 25°C, typical output is 5.0V; minimum is 4.9V and maximum is 5.2V per the Electrical Characteristics table. This tight regulation is achieved via laser-trimmed internal resistive divider referenced to a 1.25V bandgap.

Does the LTC1265CS-5#TRPBF require external feedback resistors to set the output voltage?

No, the LTC1265CS-5#TRPBF does not require external feedback resistors. Its 5V output is set by an internal precision resistive divider connected to SENSE– (Pin 7). Pin 9 (VFB) is unconnected (N/C) in this variant - unlike the adjustable LTC1265, which uses Pin 9 for external resistor feedback. This simplifies design and improves accuracy by eliminating resistor tolerance and layout sensitivity.

How does the LTC1265CS-5#TRPBF achieve low quiescent current in light-load conditions?

The LTC1265CS-5#TRPBF achieves 160µA typical quiescent current through Burst Mode™ operation: when load current drops below ~25mA, the device enters sleep mode, disabling the oscillator, current comparator, and most internal circuitry. Only the voltage comparator and reference remain active, waking the regulator only when output voltage droops beyond hysteresis. This architecture avoids gate charge losses that dominate traditional PWM at light loads.

Can the LTC1265CS-5#TRPBF operate in dropout, and what happens to efficiency?

Yes, the LTC1265CS-5#TRPBF supports 100% duty cycle operation in dropout - when VIN approaches VOUT, the internal P-channel MOSFET remains fully enhanced, delivering VOUT ≅ VIN – I_LOAD×R_DS(ON). Efficiency remains high (>85%) even at VIN = 5.5V due to low R_DS(ON) (0.3Ω typ), but drops linearly as (VIN–VOUT) shrinks because conduction loss dominates. No frequency foldback or instability occurs.

What is the function of the CT pin (Pin 5) on the LTC1265CS-5#TRPBF, and how is its value selected?

The CT pin (Pin 5) connects to an external capacitor that sets the switch off time (t_OFF) in the LTC1265CS-5#TRPBF's constant off-time architecture. For example, a 130pF capacitor yields ~700kHz at VIN=12V, VOUT=5V. CT value is calculated as CT = 1/(1.3×10⁴×f) × (VIN–VOUT)/(VIN+V_D), where V_D is Schottky forward drop. Larger CT lowers frequency and reduces gate charge loss but increases inductor size.