Analog Devices Inc. LT1934IDCB-1#TRPBF

Overview

LT1934IDCB-1#TRPBF from Analog Devices (formerly Linear Technology) is a micropower step-down DC/DC converter with integrated 75mA current-limited bipolar NPN power switch, housed in a 2mm × 3mm × 0.8mm 6-pin DFN package with exposed thermal pad. It operates from 3.2V to 34V input, delivers up to 60mA at 3.3V or 5V output, and achieves 12μA quiescent current with <1μA shutdown current-enabling long battery life in portable industrial sensors and automotive standby rails.

For engineers reviewing the LT1934IDCB-1#TRPBF datasheet, LT1934IDCB-1#TRPBF pinout, LT1934IDCB-1#TRPBF application, or LT1934IDCB-1#TRPBF equivalent, key selection criteria include its 1.25V feedback reference, 1.8μs fixed off-time Burst Mode® control, 75mA switch current limit, and compatibility with low-ESR ceramic or polymer output capacitors in space-constrained designs.

Technical Context

The LT1934IDCB-1#TRPBF uses a fixed-frequency Burst Mode® architecture with 1.8μs off-time one-shot and adjustable on-time governed by peak-current limiting. Its internal bipolar NPN switch features 70mV V_CE(SAT) at 75mA (DFN package), enabling high efficiency at light loads without external compensation.

Feedback regulation targets 1.25V at the FB pin with ±10mV hysteresis and 0.007%/V line regulation; undervoltage lockout engages below 3.2V (typical), and shutdown disables all circuitry except leakage paths, reducing VIN current to <1μA.

Key Specifications

Pinout & Package

LT1934IDCB-1#TRPBF is packaged in a 6-lead (2mm × 3mm) plastic DFN with exposed thermal pad (Pin 7), rated for –40°C to +125°C operation. The exposed pad is electrically GND and must be soldered to a PCB thermal plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT1934EDCB-1#TRPBF, the LT1934IDCB-1#TRPBF provides guaranteed 125°C operation and tighter thermal resistance-critical for under-hood or sealed industrial enclosures-while TPS62231DRYR trades input voltage range and temperature rating for higher switching frequency and synchronous rectification in low-voltage applications.

Availability

LT1934IDCB-1#TRPBF is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, and portable medical diagnostics requiring stable component supply with guaranteed 125°C operation and long-term lifecycle support.

Supply support for LT1934IDCB-1#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 full product support, datasheet documentation, and application engineering for legacy Linear parts including the LT1934 family.

The LT1934 series was designed specifically for micropower, wide-input-voltage DC/DC conversion in battery-backed and automotive systems-emphasizing ultra-low quiescent current, robust transient handling, and minimal external component count.

FAQ

What is the maximum output current supported by the LT1934IDCB-1#TRPBF?

The LT1934IDCB-1#TRPBF supports up to 60mA output current at either 3.3V or 5V, limited by its 75mA internal switch current threshold. This is confirmed in the Electrical Characteristics table (switch current limit: 90mA min, 120mA typ, 160mA max) and the "Which One to Use" section, which states the LT1934-1 variant is intended for loads under 60mA. Output capability depends on inductor selection and input voltage per Table 1.

Does the LT1934IDCB-1#TRPBF require an external catch diode?

Yes, the LT1934IDCB-1#TRPBF requires an external Schottky catch diode (e.g., ON Semiconductor MBR0540) connected between SW and GND. The device uses an asynchronous architecture with an internal bipolar NPN switch and no synchronous rectifier. The diode's reverse voltage rating must exceed the maximum input voltage (≤34V), and its forward current rating should support peak inductor current.

How does the BOOST pin function in the LT1934IDCB-1#TRPBF circuit?

The BOOST pin on the LT1934IDCB-1#TRPBF supplies gate drive voltage to the internal NPN switch, requiring a voltage ≥2.5V above the SW node for full saturation. It is charged via an external diode and capacitor (typically 0.1μF) from the SW node. Figure 2a in the datasheet shows the standard configuration where the diode anode ties to VOUT; this ensures efficient boost voltage generation and stable operation across the full input range.

Can the LT1934IDCB-1#TRPBF operate with a 3.0V input supply?

No-the LT1934IDCB-1#TRPBF has a minimum input voltage of 3.2V (typical) due to its undervoltage lockout (UVLO) threshold. At 3.0V, the device will remain in shutdown and deliver no output. For battery-powered systems nearing end-of-life, consider using a lower-UVLO regulator or designing with headroom (e.g., start regulation at 3.3V and tolerate dropout to 3.2V).

What is the purpose of the exposed thermal pad on the LT1934IDCB-1#TRPBF DFN package?

The exposed thermal pad (Pin 7) on the LT1934IDCB-1#TRPBF is electrically connected to GND and serves dual purposes: it provides a low-thermal-resistance path (θ_JC = 12°C/W) to dissipate heat from the internal switch, and it reduces high-frequency noise coupling. Per the datasheet, this pad must be soldered to a PCB ground plane-failure to do so risks thermal runaway and degraded efficiency at elevated loads or temperatures.