LT3971EMSE#PBF - 38V, 1.2A, 2MHz Buck Regulator | Analog Devices
MPN： LT3971EMSE#PBF ✓ 啟用中LT3971EMSE#PBF 概覽
A buck (step-down) switching regulator is a type of DC-DC converter that efficiently reduces a higher DC input voltage to a lower DC output voltage by rapidly switching a power transistor and storing energy in an inductor. Buck regulators occupy the middle tier of the power-management hierarchy: DC-DC converter -> switching regulator -> buck converter -> power management IC. They are preferred over linear regulators in high-ratio step-down applications because they avoid the large (VIN-VOUT) x IOUT power dissipation inherent to LDOs, achieving typical efficiencies of 85-95%.
Key features of the LT3971EMSE#PBF include low ripple Burst Mode operation for high efficiency at light loads, an accurate 1V threshold enable pin (with 700nA shutdown current), a soft-start pin for controlled inrush current, and a power-good flag that signals when VOUT reaches 91% of the programmed value. The internal compensation and 1.2A switch current rating simplify design while reducing external BOM count. The 10-pin MSOP exposed pad package provides a low thermal-resistance path, supporting full 1.2A operation in industrial temperature grades (E: 0C to 125C junction, -40C to 125C by design).
Typical applications include automotive battery regulation, industrial 24V bus point-of-load conversion, distributed power systems, portable battery-powered equipment, and always-on alarm/keep-alive supplies where the 2.8uA quiescent current is critical. When designing with the LT3971EMSE#PBF, choose the inductor and input/output capacitors based on the programmed switching frequency and load transients; higher switching frequencies permit smaller inductors but trade off switch losses.
直接替換替代品，適用於 LT3971EMSE#PBF — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： LT3971EMSE#PBF （相同外形與佔位） — 差異在於 Package, Switching Frequency, Topology, Operating Temperature Range, Quiescent Current.
LT3971EMSE-3.3#PBF
✅ 直接替換聯絡詢價
查看資料表 →LT3971EMSE-5#PBF
✅ 直接替換📋 參考替代品（不在目錄中）
LT3971IMSE#PBF
✅ 直接替換📋 參考替代品（不在目錄中）
LT3971IMSE-3.3#PBF
✅ 直接替換📋 參考替代品（不在目錄中）
LT3971IMSE-5#PBF
✅ 直接替換📋 參考替代品（不在目錄中）
LM2841YMK-ADJL
✅ 直接替換聯絡詢價
查看資料表 →LT3971EMSE#PBF 最大額定值與電氣特性
| 拓撲 | Buck (Step-Down) |
| 輸入電壓範圍 | 4.3 V to 38 V |
| 輸出電壓範圍 | 1.19 V to 30 V (adjustable) |
| 最大輸出電流 | 1.2 A |
| 切換頻率 | 200 kHz to 2 MHz (adjustable) |
| 靜態電流 | 2.8 uA (Burst Mode, no load) |
| 關機電流 | 700 nA (EN low) |
| Enable Threshold | 1 V (accurate) |
| 工作接面溫度 | -40C to +125C (E grade by design, characterized 0C to 125C) |
| 封裝 | 10-TFSOP / 10-MSOP (0.118", 3.00 mm) Exposed Pad |
| Package Code | MSE (MSOP-10EPD) |
| 安裝類型 | Surface Mount |
| Soft-Start Pin | Yes (SS capacitor controls inrush) |
| Power Good Flag | Yes (asserts at 91% of VOUT) |
| Lead-Free / RoHS | Yes (PBF suffix indicates lead-free) |
LT3971EMSE#PBF 腳位配置
| 腳位 1 | EN — Enable pin (1V accurate threshold); drive high to enable, low to shutdown (700nA Iq) |
| 腳位 2 | VIN — Input supply voltage (4.3V to 38V) |
| 腳位 3 | SW — Switch node - connected to inductor |
| 腳位 4 | BST — Bootstrap pin for high-side gate drive |
| 腳位 5 | PGND — Power ground |
| 腳位 6 | RT — Timing resistor - sets switching frequency 200kHz to 2MHz |
| 腳位 7 | SS — Soft-start - capacitor to GND sets inrush time |
| 腳位 8 | PG — Power good flag - open-drain output, asserts at 91% of VOUT |
| 腳位 9 | FB — Feedback (adjustable version); VOUT = 1.19V x (1 + R1/R2) |
| 腳位 10 | AGND — Analog ground |
| 腳位 11 | EP — Exposed pad (thermal) - solder to PCB ground pour |
典型應用
LT3971EMSE#PBF 適用於 6 應用s: Automotive 12V Battery Point-of-Load, Industrial 24V Bus Distributed Power, Battery-Powered Portable Equipment, Always-On Alarm and Keep-Alive Supply, Distributed Power Systems, General-Purpose 5V/3.3V System Rails.
Automotive 12V Battery Point-of-Load
The LT3971EMSE#PBF is well suited for automotive 12V battery rails because its 38V maximum input withstands 24V jump-start transients and load-dump events, while its 2.8uA quiescent current is critical for always-on modules that must not drain the battery when the ignition is off. The 1.2A switch can power infotainment processors, CAN transceivers, or sensor clusters directly from VBAT. Compared to an LDO, the buck topology dissipates far less heat at large VIN-VOUT deltas, enabling smaller PCB area and lighter thermal management.
推薦
Industrial 24V Bus Distributed Power
On industrial 24V bus systems, the LT3971EMSE#PBF operates directly from the bus without a pre-regulator, providing isolated point-of-load rails for sensors, actuators, and PLC I/O. Its 4.3V to 38V input accommodates the 18V to 32V industrial envelope including transients, while the 200kHz to 2MHz programmable frequency allows designers to balance efficiency against component size. The integrated soft-start prevents inrush into large bulk capacitors when many modules power up simultaneously on the same backplane.
推薦
Battery-Powered Portable Equipment
The LT3971EMSE#PBF is excellent for portable battery-powered equipment because its 2.8uA quiescent current extends standby life when the load is sleeping, and its 700nA shutdown current (EN low) further reduces drain during shipping or storage. The adjustable switching frequency up to 2MHz enables tiny chip inductors under 4.7uH, reducing solution footprint for handheld instruments. Burst Mode operation eliminates audible switching noise at light loads, important for medical and audio accessories.
推薦
Always-On Alarm and Keep-Alive Supply
For always-on alarm and keep-alive circuits that must operate for years on a primary cell or backup battery, the LT3971EMSE#PBF's 2.8uA Iq ensures negligible standby drain while maintaining a regulated output to RTCs, tamper detectors, and supervisory MCUs. The enable pin allows the main system to switch off the regulator entirely when in deep sleep, dropping quiescent current to 700nA. Power-good flag simplifies coordination with the host MCU's reset sequencing.
推薦
Distributed Power Systems
In distributed power architectures, the LT3971EMSE#PBF serves as a downstream POL (point-of-load) converter placed at each load, stepping down an intermediate 12V or 24V bus to local MCU voltages (3.3V, 5V, 1.8V). Its small MSOP-10EPD footprint and high switching frequency minimize PCB area per converter. The accurate 1V EN threshold permits direct connection to a GPIO without level translation, simplifying sequencing in multi-rail FPGA or DSP power trees.
推薦
General-Purpose 5V/3.3V System Rails
As a general-purpose 5V or 3.3V system rail source, the LT3971EMSE#PBF (used in its adjustable variant or the -3.3/-5 fixed variants) supplies microcontrollers, sensors, and communication ICs across a wide input range. Its 1.2A switch rating covers typical MCU plus peripheral loads, while Burst Mode ensures high efficiency at light loads common in idle or sleep modes. The integrated compensation eliminates the loop compensation network that simpler bucks require, reducing BOM and design time.
推薦
推薦產品摘要
工程參考資料，適用於 LT3971EMSE#PBF — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | LT3971EMSE-3.3#PBF | LT3971EMSE-5#PBF | LT3971IMSE#PBF | LT3971IMSE-3.3#PBF | LT3971IMSE-5#PBF | LM2841YMK-ADJL |
|---|---|---|---|---|---|---|---|
| Package | MSOP-10EPD (MSE) | MSOP-10EPD (MSE) - same | MSOP-10EPD (MSE) - same | MSOP-10EPD (MSE) - same | MSOP-10EPD (MSE) - same | MSOP-10EPD (MSE) - same | MSOP-10EPD - same footprint |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Texas Instruments |
| Input Voltage Range | 4.3 V to 38 V | 4.3 V to 38 V | 4.3 V to 38 V | 4.3 V to 38 V | 4.3 V to 38 V | 4.3 V to 38 V | 4.5 V to 42 V |
| Output Voltage | 1.19 V to 30 V (adjustable) | 3.3 V (fixed) | 5 V (fixed) | 1.19 V to 30 V (adjustable) | 3.3 V (fixed) | 5 V (fixed) | 0.765 V to 34 V (adjustable) |
| Maximum Output Current | 1.2 A | 1.2 A | 1.2 A | 1.2 A | 1.2 A | 1.2 A | 0.3 A |
| Quiescent Current | 2.8 uA | 2.8 uA | 2.8 uA | 2.8 uA | 2.8 uA | 2.8 uA | 20 uA (typ) |
| Switching Frequency Range | 200 kHz to 2 MHz | 200 kHz to 2 MHz | 200 kHz to 2 MHz | 200 kHz to 2 MHz | 200 kHz to 2 MHz | 200 kHz to 2 MHz | 550 kHz to 1.5 MHz |
| Junction Temperature Range | -40C to +125C (E grade by design) | -40C to +125C (E grade by design) | -40C to +125C (E grade by design) | -40C to +125C (I grade guaranteed) | -40C to +125C (I grade guaranteed) | -40C to +125C (I grade guaranteed) | -40C to +125C |
主要差異化特點
- Industry-leading 2.8uA quiescent current (對比LM2841YMK-ADJL)
- Wide VIN to 38V handles 24V industrial transients (對比TPS563201)
- Up to 2MHz switching frequency with internal compensation (對比LM2841YMK-ADJL)
- Accurate 1V enable threshold and 700nA shutdown current (對比TPS563201)
設計說明
Estimated: at VIN=24V, VOUT=5V, and 1.2A load, the LT3971EMSE#PBF dissipates roughly (24-5)V x 1.2A x (1/eta - 1). Assuming 88% efficiency yields about 3.1W of waste heat. The MSE-10EPD package with proper PCB copper pour (>=1 square inch of 2oz copper tied to the exposed pad) typically achieves 40-45 C/W theta_JA, producing a junction temperature rise of approximately 130C above ambient. Derate load or add thermal relief if the design operates near full load at high VIN.
Place the input capacitor (>= 2.2uF X7R ceramic) as close as possible between VIN and PGND, with the return path short and wide. Place the bootstrap capacitor (>= 0.1uF) between BST and SW, also close to the IC. Keep the FB/ADJ trace short and away from the SW node to minimize noise injection. The exposed pad must be soldered to a continuous ground plane with thermal vias for proper heat sinking and EMI performance.
Do not exceed the absolute maximum VIN of 38V; transients above this will damage the part. The EN pin has a precise 1V threshold - if driving from a noisy GPIO, add a small RC filter (10k/100nF) to prevent false triggering. The SS capacitor must be present; without it, large inrush currents can trigger the current limit and create startup instability. Always respect the BST-to-SW voltage rating (typically 4V); design with margin for transient spikes on the SW node.
Separate power ground (PGND) and analog ground (AGND) at the IC pins, then tie them together at a single point under the exposed pad to avoid ground bounce coupling into the FB/ADJ node. Use a 4-layer PCB if possible, with the inner layer dedicated to a quiet ground plane beneath the feedback trace. Keep the inductor and input capacitor loop area minimal to reduce high-frequency ringing on the SW node.
合規資訊
PBF suffix indicates lead-free / RoHS-compliant per Analog Devices part numbering convention. E grade (standard) is not AEC-Q100 qualified; automotive applications should request ADI automotive-grade variants. Halogen-free status not confirmed in provided data.
