Analog Devices Inc. LTC1148CN-5#PBF

Overview

LTC1148CN-5#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller driving external P- and N-channel MOSFETs to deliver regulated 5V output. It features constant off-time current-mode architecture, ultrahigh efficiency (>95% at 1A), 160µA standby current in Burst Mode™, wide 3.5V–20V input range, and adaptive nonoverlap gate drives-designed for battery-powered portable instrumentation requiring high light-load efficiency and low dropout.

For engineers reviewing the LTC1148CN-5#PBF datasheet, LTC1148CN-5#PBF pinout, LTC1148CN-5#PBF application, or LTC1148CN-5#PBF equivalent, key selection criteria include its fixed 5V output version, 14-pin narrow SO package, programmable current limit via R_SENSE, shutdown threshold of 0.55–2V, and compatibility with external synchronous rectification for >95% peak efficiency.

Technical Context

The LTC1148CN-5#PBF implements a constant off-time current-mode control architecture with automatic transition between continuous conduction mode (CCM) and Burst Mode™ operation. Its off-time (3.8–6 µs) is set by an external CT capacitor and scales with V_OUT, enabling stable regulation down to 100% duty cycle for ultra-low dropout.

It integrates dual high-current gate drivers (P-DRIVE and N-DRIVE), internal 1.25V reference, feedback sensing via SENSE–/SENSE+, and logic-controlled micropower shutdown (I_Q < 20µA). The device does not include internal power switches-it requires external complementary MOSFETs and supports adaptive nonoverlap timing to prevent shoot-through.

Key Specifications

Pinout & Package

Package: 14-lead narrow SOIC (N), 70°C/W junction-to-ambient thermal resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with LTC1148CN-5#PBF, LTC1149CS-5#PBF extends input range to 48 V with identical functionality, while TPS40210DGQR trades Burst Mode™ efficiency for wider VIN and voltage-mode simplicity - neither is pin-compatible, but both serve overlapping controller-level functions in discrete synchronous buck designs.

Availability

LTC1148CN-5#PBF is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered digital devices, and GPS navigation systems requiring stable component supply with long-term lifecycle support.

Supply support for LTC1148CN-5#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.

The LTC1148 series was designed as a family of synchronous buck controllers targeting ultrahigh efficiency in portable and battery-sensitive applications - emphasizing Burst Mode™ operation, low I_Q, and robust gate drive for discrete MOSFET solutions.

FAQ

What is the output voltage accuracy of the LTC1148CN-5#PBF?

The LTC1148CN-5#PBF provides a fixed 5 V output with ±2% regulation over temperature and load: typical value is 5.05 V, with min/max of 4.90 V and 5.20 V at 700 mA load and TA = 25°C. This accuracy is achieved using an internal 1.25 V reference and precision resistive divider optimized for the -5 variant.

Does the LTC1148CN-5#PBF integrate power MOSFETs?

No, the LTC1148CN-5#PBF is a controller-only IC and does not integrate power switches. It drives external complementary P-channel and N-channel MOSFETs via dedicated high-current P-DRIVE and N-DRIVE pins. This architecture allows designers to optimize efficiency, thermal performance, and cost by selecting MOSFETs matched to their specific voltage, current, and layout requirements.

How does Burst Mode™ operation improve efficiency at light loads?

Burst Mode™ in the LTC1148CN-5#PBF disables switching and places the IC in micropower sleep (160 µA I_Q) until output voltage drops below regulation threshold. This eliminates switching losses entirely at loads below ~300 mA, sustaining >85% efficiency where conventional controllers drop to <60%. The LTC1148CN-5#PBF enters Burst Mode™ automatically - no external control required.

What is the purpose of the SENSE+ and SENSE– pins on the LTC1148CN-5#PBF?

SENSE+ and SENSE– form the differential current sense inputs for the internal current comparator. They connect across an external shunt resistor (R_SENSE) in series with the inductor to monitor peak inductor current. In the LTC1148CN-5#PBF, SENSE– is also tied to the internal feedback divider for 5 V regulation - enabling combined voltage and current sensing with minimal external components.

Can the LTC1148CN-5#PBF operate with 100% duty cycle for ultra-low dropout?

Yes, the LTC1148CN-5#PBF supports true 100% duty cycle operation via its constant off-time architecture. When VIN approaches VOUT, the off-time controller increases CT discharge current to maintain regulation - allowing the P-channel MOSFET to remain continuously on. This enables dropout voltages limited only by R_DS(ON) of the external P-MOSFET and inductor DCR, not by internal timing constraints.