Analog Devices Inc. LT1936EMS8E#PBF

Overview

LT1936EMS8E#PBF from Analog Devices (formerly Linear Technology) is a current-mode PWM step-down DC/DC converter with an integrated 1.9A bipolar NPN power switch, operating at a fixed 500kHz switching frequency. It accepts 3.6V to 36V input and delivers up to 1.4A at 3.3V or 5V in thermally enhanced 8-lead MSOP package. Designed for automotive battery regulation and industrial control supplies, it features cycle-by-cycle current limiting, thermal shutdown, and <2μA shutdown current.

For engineers reviewing the LT1936EMS8E#PBF datasheet, LT1936EMS8E#PBF pinout, LT1936EMS8E#PBF application, or LT1936EMS8E#PBF equivalent, key selection considerations include guaranteed 1.9A switch current, internal/external compensation flexibility, 1.200V feedback reference accuracy, short-circuit protection across full input range, and MSOP-8 exposed-pad thermal management.

Technical Context

The LT1936EMS8E#PBF implements constant-frequency current-mode control using an internal 500kHz oscillator and RS flip-flop to drive its bipolar NPN switch. Current sensing occurs between VIN and SW pins, with VC pin servoing the error amplifier output to regulate FB at 1.200V. An active clamp on VC provides current limit, while SHDN pin voltage ramp enables soft-start.

Frequency foldback reduces switching frequency when FB voltage drops low-critical during startup or overload-to limit output current. The BOOST pin supplies elevated gate drive via external diode/capacitor, enabling full saturation of the internal switch; minimum BOOST-to-SW voltage is 2.2V, and absolute max BOOST voltage is 43V.

Key Specifications

Pinout & Package

The LT1936EMS8E#PBF is housed in an 8-lead plastic MSOP package (MS8E) with exposed pad (Pin 9), which must be soldered to PCB ground for thermal and electrical integrity. θJA = 40°C/W, θJC = 10°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3605EMS8E#PBF and LM2678SX-5.0/NOPB, the LT1936EMS8E#PBF uniquely balances 36V input tolerance, 500kHz switching, integrated bipolar switch, and MSOP-8 thermal performance - making it optimal for space-constrained industrial and automotive point-of-load regulation where input transients and reliability are critical.

Availability

LT1936EMS8E#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control supplies, and unregulated wall adapter interfaces requiring stable component supply, extended temperature operation, and long-term production continuity.

Supply support for LT1936EMS8E#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, serving precision instrumentation, industrial automation, and automotive markets.

The LT1936EMS8E#PBF belongs to Linear's legacy high-voltage buck regulator product line, engineered specifically for robust, wide-input DC/DC conversion in harsh environments - emphasizing fault tolerance, thermal resilience, and minimal external component count.

FAQ

What is the guaranteed minimum switch current for LT1936EMS8E#PBF?

The LT1936EMS8E#PBF guarantees a minimum switch current of 1.9A across its full operating temperature range (–40°C to +85°C). This rating ensures reliable 1.4A continuous output at 3.3V or 5V under worst-case thermal and voltage conditions, validated by design correlation and characterization per Linear Technology's datasheet specifications.

Can LT1936EMS8E#PBF operate with a 3.3V input?

No, the LT1936EMS8E#PBF cannot operate with a 3.3V input. Its undervoltage lockout triggers below ~3.45V, and minimum functional input is 3.6V. For 3.3V input applications, consider alternatives like the LTC3605 (2.5V–5.5V input) or redesign with a higher input source - the LT1936EMS8E#PBF is optimized for 12V/24V/36V industrial and automotive rails.

How does the BOOST pin function in LT1936EMS8E#PBF, and what external components are required?

The BOOST pin in LT1936EMS8E#PBF supplies elevated gate drive to fully saturate its internal bipolar NPN switch. It requires an external fast-switching diode (e.g., 1N4148 or DFLS140L) and capacitor (typically 0.22μF ceramic). BOOST must remain ≥2.2V above SW; maximum BOOST voltage is 43V. Incorrect BOOST implementation causes reduced efficiency or switch failure - refer to Figure 3a/b in the LT1936EMS8E#PBF datasheet for topology guidance.

Does LT1936EMS8E#PBF support adjustable output voltages below 3.3V?

Yes, the LT1936EMS8E#PBF supports adjustable output voltages down to 1.20V using the FB pin and external resistor divider. Its 1.200V ±15mV reference enables precise programming - e.g., 2.5V output uses R1/R2 = 1.083; 1.8V uses R1/R2 = 0.5. Ensure R2 ≤20kΩ to minimize bias current error, and verify stability with appropriate output capacitance per the LT1936EMS8E#PBF compensation guidelines.

What thermal design practices are required for LT1936EMS8E#PBF to sustain 1.4A output?

To sustain 1.4A output, the LT1936EMS8E#PBF requires its exposed pad (Pin 9) to be soldered to a solid PCB ground plane with ≥4 thermal vias (0.3mm diameter) connecting to inner/ground layers. Layout must minimize copper resistance between GND pin and pad, and keep high-current SW/GND loops compact. With θJA = 40°C/W, ambient must stay ≤65°C for safe operation - derate linearly above that per the LT1936EMS8E#PBF thermal curves.