Analog Devices Inc. LT1956IFE-5#TRPBF

Overview

LT1956IFE-5#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage, fixed 5V-output synchronous buck switching regulator with 5.5V–60V input range, 1.5A peak switch current, 0.2Ω on-resistance, constant 500kHz switching frequency, and thermally enhanced 16-pin TSSOP package. It delivers regulated 5V power in industrial battery chargers and distributed power systems.

For engineers reviewing the LT1956IFE-5#TRPBF datasheet, LT1956IFE-5#TRPBF pinout, LT1956IFE-5#TRPBF application, or LT1956IFE-5#TRPBF equivalent, key selection criteria include its fixed 5V output, 60V max input, cycle-by-cycle current limiting, shutdown current of 25µA, and thermal performance in the exposed-pad TSSOP package.

Technical Context

The LT1956IFE-5#TRPBF implements a current-mode architecture with an internal 500kHz oscillator, integrated 1.5A NPN power switch, and patented circuitry maintaining peak switch current across full duty cycle range. It uses BOOST pin voltage (up to 68V) to saturate the switch and achieve low conduction loss.

Its SENSE pin (replaces FB in fixed-output variants) connects directly to VOUT for regulation; SHDN provides dual-threshold control (0.4V full shutdown, 2.38V UVLO), and SYNC enables external synchronization from 580kHz to 700kHz with logic-level input.

Key Specifications

Pinout & Package

LT1956IFE-5#TRPBF is housed in a 16-lead plastic TSSOP package with exposed thermal pad (FE package). The exposed pad must be soldered to a PCB ground plane for thermal management (θJC = 10°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output buck regulator applications.

Compared with LTC3642EMSE-5#TRPBF and LM5164QPWPRQ1, LT1956IFE-5#TRPBF uniquely combines 60V input capability, 1.5A current, fixed 5V output, and BOOST-driven bipolar switch in a thermally optimized TSSOP-making it optimal for unregulated high-voltage industrial supplies where efficiency at partial load and transient robustness are critical.

Availability

LT1956IFE-5#TRPBF is available at Aetrix Electronics and suitable for industrial battery chargers, automotive power distribution modules, and distributed DC power systems requiring stable component supply with guaranteed long-term availability.

Supply support for LT1956IFE-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 acquired Linear Technology in 2017 and maintains its high-performance power management portfolio with rigorous industrial and automotive qualification standards.

The LT1956 family was designed specifically for high-input-voltage buck conversion in harsh environments-targeting applications where input transients exceed 40V and thermal management is constrained by enclosure size or airflow.

FAQ

What is the absolute maximum input voltage rating for LT1956IFE-5#TRPBF?

The absolute maximum input voltage for LT1956IFE-5#TRPBF is 60V, as specified in the Absolute Maximum Ratings table. Exceeding this voltage-even momentarily-may impair device reliability. The part is designed to withstand common industrial transients such as 60V load dumps, but sustained operation above 60V is not permitted. Always verify input clamping or filtering networks when using LT1956IFE-5#TRPBF in systems with potential overvoltage events.

Can LT1956IFE-5#TRPBF operate with input voltage below 5.5V?

No, LT1956IFE-5#TRPBF requires a minimum input voltage of 5.5V to maintain regulation and internal bias stability. Below this threshold, the internal 2.9V bias regulator cannot sustain oscillator and error amplifier operation, causing loss of regulation and unpredictable behavior. The datasheet specifies 5.5V as the guaranteed minimum; actual functional start-up may occur slightly lower (e.g., 4.6V per Note 3), but regulation and specifications are not assured.

How does the BOOST pin function in LT1956IFE-5#TRPBF, and what happens if it's left unconnected?

The BOOST pin supplies elevated gate drive to the internal NPN switch, enabling saturation and achieving 0.2Ω effective on-resistance. It must be connected to a charge-pump network (diode + capacitor referenced to SW). If left unconnected, the switch operates in linear mode with ~1.5V V_CE(sat), drastically increasing conduction loss and thermal stress. Efficiency drops significantly, and the part may fail to regulate under load. LT1956IFE-5#TRPBF will not function reliably without proper BOOST implementation.

Is LT1956IFE-5#TRPBF pin-compatible with LT1956IFE#TRPBF?

No, LT1956IFE-5#TRPBF and LT1956IFE#TRPBF are not pin-compatible. While both use the same 16-pin TSSOP package and share identical pinouts, their FB/SENSE functionality differs fundamentally: LT1956IFE-5#TRPBF uses Pin 12 as SENSE (internally connected to 5V output), whereas LT1956IFE#TRPBF uses Pin 12 as FB (requiring external resistor divider for adjustable output). Interchanging them without circuit modification will cause regulation failure.

What thermal design considerations apply to the exposed pad on LT1956IFE-5#TRPBF?

The exposed thermal pad on LT1956IFE-5#TRPBF must be soldered to a solid copper ground plane to achieve θJC = 10°C/W. Use ≥4 thermal vias (0.3mm diameter, filled or plated) connecting the pad to inner/ground layers. Avoid solder mask over the pad. Insufficient thermal relief causes junction temperature to exceed 125°C under 1A load at 70°C ambient, triggering overtemperature protection and reducing reliability. Thermal performance directly determines maximum continuous output current.