Analog Devices Inc. LT3970HMS-3.3#TRPBF

Overview

LT3970HMS-3.3#TRPBF from Analog Devices is a 40V input, 350mA fixed-output step-down regulator in a 10-lead MSOP package, featuring 2.5µA quiescent current, integrated boost and catch diodes, and a power good flag. It delivers stable 3.3V output for automotive battery regulation and industrial supplies requiring high efficiency at light loads.

For engineers reviewing the LT3970HMS-3.3#TRPBF datasheet, LT3970HMS-3.3#TRPBF pinout, LT3970HMS-3.3#TRPBF application, or LT3970HMS-3.3#TRPBF equivalent, this page provides verified specifications, thermal-grade packaging details (–40°C to 150°C), Burst Mode ripple performance (<5mV_P-P), and real-world substitution guidance for automotive and industrial DC/DC designs.

Technical Context

The LT3970HMS-3.3#TRPBF uses current-mode control with internal compensation and a programmable 200kHz–2.2MHz switching frequency via RT pin resistor. Its bipolar NPN switch is driven by an external BOOST capacitor to ensure full saturation, enabling efficient operation across wide input ranges.

Burst Mode operation maintains high efficiency at light loads while limiting output ripple to <5mV_P-P; the power good flag asserts when V_OUT reaches 90% of 3.3V (i.e., 2.97V), and the enable pin features accurate 1V threshold with 30mV hysteresis.

Key Specifications

Pinout & Package

LT3970HMS-3.3#TRPBF is housed in a 10-lead plastic MSOP package (θ_JA = 100°C/W), with exposed pad not present (unlike DFN variant). Pin 1 is VOUT (fixed 3.3V feedback node), Pin 2 is EN, Pin 3 is VIN, Pins 4 & 5 are GND, Pin 6 is SW, Pin 7 is BOOST, Pin 8 is BD, Pin 9 is PG, and Pin 10 is RT.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8609SIV-3.3#TRPBF and TPS54332DDAR, the LT3970HMS-3.3#TRPBF uniquely combines AEC-Q100 H-grade qualification, integrated diodes, sub-5mV ripple in Burst Mode, and 40V input - making it optimal for space-constrained, thermally demanding automotive and industrial point-of-load applications where reliability and simplicity are prioritized over raw current capability or ultra-low EMI.

Availability

LT3970HMS-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial sensor power supplies, and portable medical device power requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant thermal performance.

Supply support for LT3970HMS-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.

The LT3970 series is designed for high-efficiency, low-quiescent-current step-down conversion in harsh environments - specifically targeting automotive infotainment, ADAS, and industrial control applications needing wide input range and extended temperature operation.

FAQ

What is the guaranteed operating temperature range for LT3970HMS-3.3#TRPBF?

The LT3970HMS-3.3#TRPBF is an H-grade device with a guaranteed operating junction temperature range of –40°C to 150°C, fully qualified per AEC-Q100 for automotive under-hood applications. This specification is explicitly confirmed in the Order Information table and Electrical Characteristics section of the official datasheet, where LT3970HMS-3.3#TRPBF is listed with "–40°C to 150°C" under Temperature Range.

Does LT3970HMS-3.3#TRPBF require external feedback resistors?

No, the LT3970HMS-3.3#TRPBF does not require external feedback resistors. As a fixed-output variant, it internally regulates the VOUT pin (Pin 1) to 3.3V ±1.0% across temperature, eliminating the need for an external resistor divider. This is clearly stated in the PIN FUNCTIONS section: "VOUT (Pin 1, LT3970-X Only): The LT3970-3.3 [...] regulate the VOUT Pin to 3.3V [...] This pin connects to the internal feedback divider that programs the fixed output voltage."

What is the maximum continuous output current of LT3970HMS-3.3#TRPBF?

The LT3970HMS-3.3#TRPBF delivers up to 350mA continuous output current, as specified in the FEATURES section and confirmed in the ELECTRICAL CHARACTERISTICS table under "Catch Schottky Current Limit" (350mA typ, 400mA min). This limit is enforced by the internal catch diode valley current protection, which prevents thermal runaway during sustained loads or short-circuit conditions.

How does the power good (PG) flag behave on LT3970HMS-3.3#TRPBF?

The PG pin on LT3970HMS-3.3#TRPBF is an open-drain output that remains low until VOUT reaches 90% of its nominal 3.3V value (i.e., 2.97V), then pulls high via an external pull-up. It is valid only when VIN > 4.2V and EN is high, and exhibits 12mV hysteresis. This behavior is documented in the PIN FUNCTIONS section and Typical Performance Characteristics graph G25, ensuring precise system power sequencing.

Can LT3970HMS-3.3#TRPBF operate with input voltages below 4.2V?

No, LT3970HMS-3.3#TRPBF requires a minimum input voltage of 4.2V to operate, as defined in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this threshold, the internal regulator cannot sustain bias, EN threshold accuracy is lost, and PG flag becomes invalid. The datasheet explicitly states: "Power good is valid when the LT3970 is enabled and VIN is above 4.2V," and lists "Minimum Input Voltage" as 4.2V (typical) across all grades.