Analog Devices Inc. LT3990IMSE-3.3#TRPBF

Overview

LT3990IMSE-3.3#TRPBF from Analog Devices is a 62V, 350mA monolithic step-down regulator with fixed 3.3V output, 2.5µA quiescent current at 12V_IN, integrated boost and catch Schottky diodes, and low-ripple Burst Mode operation delivering <5mV_P-P output ripple. It serves as a primary DC/DC power supply in automotive battery regulation and industrial 24V/48V systems requiring high input voltage tolerance and ultra-low standby power.

For engineers reviewing the LT3990IMSE-3.3#TRPBF datasheet, LT3990IMSE-3.3#TRPBF pinout, LT3990IMSE-3.3#TRPBF application, or LT3990IMSE-3.3#TRPBF equivalent, key selection criteria include its guaranteed –40°C to 125°C operating junction temperature, AEC-Q100 qualification, integrated diode architecture eliminating external diode BOM, and FMEA-fault-tolerant MSOP package with redundant VOUT pins and floating-pin short-circuit resilience.

Technical Context

The LT3990IMSE-3.3#TRPBF implements constant-frequency current-mode control with programmable switching frequency (200kHz–2.2MHz) via RT resistor, enabling optimization of inductor size versus efficiency. Its internal bipolar NPN switch is driven by a charge-pump boosted gate voltage generated at the BOOST pin, allowing full saturation across the 4.2V–62V input range.

Burst Mode operation reduces quiescent current to 1.8µA at light loads while maintaining output regulation and limiting peak-to-peak ripple to <5mV. Protection includes catch diode current limit (450mA typical), accurate programmable undervoltage lockout (1.19V threshold with 35mV hysteresis), and power good flag signaling when V_OUT reaches 90% of nominal.

Key Specifications

Pinout & Package

LT3990IMSE-3.3#TRPBF uses a thermally enhanced 16-lead plastic MSOP package with exposed pad (Pin 17 = GND). The package provides θ_JA = 40°C/W and supports high-power density layouts in space-constrained automotive and industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3639EMSE-3.3#PBF and TPS54331DR, LT3990IMSE-3.3#TRPBF uniquely combines 62V input tolerance, integrated diodes, AEC-Q100 qualification, and 2.5µA quiescent current in a single 16-pin MSOP-making it the only option for robust, space-constrained automotive and industrial 48V systems requiring zero external diodes.

Availability

LT3990IMSE-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial 24V/48V power supplies, and portable medical instrumentation requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.

Supply support for LT3990IMSE-3.3#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving automotive, industrial, communications, and healthcare markets.

The LT3990 product line delivers high-voltage, low-I_Q monolithic buck regulators with integrated diodes and automotive qualification-designed specifically for next-generation 48V mild-hybrid vehicles, industrial IoT edge nodes, and ruggedized portable equipment.

FAQ

What is the guaranteed operating temperature range for LT3990IMSE-3.3#TRPBF?

The LT3990IMSE-3.3#TRPBF is guaranteed to operate over a junction temperature range of –40°C to 125°C, meeting AEC-Q100 Grade I requirements. This specification is validated through production testing and thermal characterization-not just design assurance-and applies across the full input voltage range (4.2V–62V) and load conditions up to 350mA.

Does LT3990IMSE-3.3#TRPBF require external feedback resistors to set the output voltage?

No, LT3990IMSE-3.3#TRPBF does not require external feedback resistors. It features a factory-trimmed internal resistor divider that regulates the VOUT pins precisely to 3.3V ±1.2% across temperature and line. Pins 1 and 2 are internally connected VOUT terminals-both must be tied to the output node to maintain FMEA fault tolerance.

How does the integrated catch diode in LT3990IMSE-3.3#TRPBF improve system reliability?

The integrated catch Schottky diode in LT3990IMSE-3.3#TRPBF eliminates variability from external diode selection, ensures matched thermal behavior with the switch, and removes solder joint failure points. Its 450mA valley current limit provides inherent short-circuit protection, and its 725mV forward voltage at 100mA contributes directly to the device's high efficiency across load conditions.

Can LT3990IMSE-3.3#TRPBF operate with input voltages below 4.2V?

No, LT3990IMSE-3.3#TRPBF requires a minimum input voltage of 4.2V for normal regulation. Below this, the internal circuitry cannot sustain proper bias and the EN/UVLO comparator becomes inaccurate. If VIN drops below 4.2V, the part must be actively disabled by pulling EN/UVLO low to ensure predictable shutdown with only 0.7µA quiescent current.

What is the purpose of the dual VOUT pins (Pins 1 and 2) on LT3990IMSE-3.3#TRPBF?

The dual VOUT pins on LT3990IMSE-3.3#TRPBF provide redundant connection paths to the internal fixed 3.3V feedback network. This design enhances fault tolerance: if one pin experiences a short to adjacent net or opens due to solder void, the other maintains regulation integrity-fulfilling FMEA requirements for automotive ASIL-B systems and improving field reliability in high-vibration environments.