LT3971EMSE-3.3#PBF - 38V, 1.2A, 2MHz Buck Regulator | Analog Devices
MPN: LT3971EMSE-3.3#PBF ✓ Hoạt độngLT3971EMSE-3.3#PBF Tóm tắt
A buck (step-down) switching regulator is a DC-DC converter that efficiently reduces a higher DC input voltage to a lower DC output voltage by rapidly switching a power transistor and smoothing the resulting pulse train with an LC filter. The LT3971 family occupies the hierarchy: buck regulator → switching regulator → DC-DC converter → power management IC → semiconductor. Compared with linear regulators, buck regulators achieve much higher efficiency at large VIN/VOUT ratios, making them preferred for battery-powered and automotive systems where thermal dissipation is a concern.
The LT3971's key features include a 4.3V to 38V input range, integrated power switch, 700 nA shutdown supply current (via an accurate 1V threshold enable pin), programmable soft-start with a capacitor on the SS pin, and a power-good flag that asserts at 91% of the programmed output voltage. The MSE package combines a small 10-pin MSOP outline with an exposed thermal pad for low thermal resistance.
Internally, the LT3971 uses a current-mode control topology with Burst Mode operation that allows the regulator to maintain output voltage with only 2.8 µA quiescent current at no load - ideal for always-on battery systems. The high 2 MHz switching capability supports small inductor and capacitor selection, while the 38V absolute maximum input accommodates load-dump and cold-crank transients in 12V automotive rails.
Typical applications include automotive battery-powered systems, industrial control supplies, portable instrumentation, distributed supply regulation in 24V industrial buses, and always-on housekeeping rails in IoT nodes. The wide VIN range also suits solar and telecom point-of-load regulation downstream of a higher-voltage bus.
When designing, prioritize input bulk capacitance to handle inductor ripple, place the BST capacitor close to the SW and BST pins, and use a low-ESR ceramic output capacitor for ripple performance. The exposed pad must be soldered to a sufficiently large copper pour to keep junction temperature within the 125°C limit.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho LT3971EMSE-3.3#PBF — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với LT3971EMSE-3.3#PBF (cùng hình factor và footprint) — khác nhau ở Package, Quiescent Current, RoHS Status, Switching Frequency, Input Voltage Range.
LT3971EMSE-3.3#TRPBF
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LT3971EMSE#PBF
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →LT3971EMSE-5#PBF
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LT3971EMSE-3.3
✅ Drop-In ⚠️ Thông số chưa được xác minhLiên hệ để biết giá
Xem tài liệu →LT3971IMSE-3.3#PBF
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
LT3971HMSE-3.3#PBF
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
LT3971EMSE-3.3#PBF Tỷ lệ tối đa & tính chất điện
| Cấu trúc | Buck (Step-Down) |
| Phạm vi điện áp đầu vào | 4.3 V to 38 V |
| Điện áp đầu ra | 3.3 V (fixed) |
| Điện áp tối đa đầu ra | 1.2 A |
| Tần số chuyển đổi | Up to 2 MHz (adjustable) |
| Điện áp yên tĩnh | 2.8 µA (Burst Mode, no load) |
| Shutdown Supply Current | 700 nA |
| Khoảng nhiệt độ hoạt động | -40 °C to +125 °C |
| Hộp | 10-MSOP with Exposed Pad (MSE), 3.00 mm width |
| Kiểu lắp đặt | Surface Mount |
| Enable Pin Threshold | 1 V (accurate) |
| Power Good Flag | Asserts at 91% of VOUT |
| Bắt đầu mềm | Programmable via SS capacitor |
| Cấp MSL | 1 (unlimited) |
| Trạng thái RoHS | Compliant (Pb-free #PBF suffix) |
Cấu hình chân LT3971EMSE-3.3#PBF
| Chân 1 | OUT — Output voltage sense (3.3 V fixed) |
| Chân 2 | VIN — Input supply voltage (4.3 V to 38 V) |
| Chân 3 | GND — Signal ground |
| Chân 4 | EN — Enable input (1 V threshold, high to enable) |
| Chân 5 | SS — Soft-start programming capacitor node |
| Chân 6 | RT — Timing resistor for switching frequency |
| Chân 7 | PGOOD — Power-good flag (open-drain, asserts at 91% of VOUT) |
| Chân 8 | BST — Boost capacitor for high-side gate drive |
| Chân 9 | SW — Switch node (connect to inductor) |
| Chân 10 | PGND — Power ground (connect to exposed pad) |
Ứng dụng tiêu biểu
LT3971EMSE-3.3#PBF phù hợp cho 6 Áp dụngs: Automotive 12V Battery-Powered Systems, Industrial 24V Sensor and Actuator Rails, Always-On IoT Housekeeping Supplies, Distributed Point-of-Load Regulation in Telecom Systems, Portable Test and Measurement Instrumentation, Solar-Powered Remote Sensor Nodes.
Automotive 12V Battery-Powered Systems
The LT3971EMSE-3.3#PBF fits automotive 12V battery rails because its 38 V maximum input withstands the ISO 7637-2 load-dump transient (typically 35 V for 400 ms). The 1.2 A output at fixed 3.3 V powers body-control modules, RKE receivers, and sensor hubs directly from the battery without a preregulator. The 2.8 µA Burst Mode quiescent current keeps quiescent drain under 100 µA even when the MCU is asleep, which helps the vehicle meet the < 100 µA quiescent-current budget mandated by many OEMs. Place the exposed pad on a 1 sq. inch copper pour to dissipate the 1 W-3 W typical load power at VIN=13.5 V, VOUT=3.3 V, IOUT=1 A.
Được đề xuất
Industrial 24V Sensor and Actuator Rails
The LT3971EMSE-3.3#PBF is well-matched to industrial 24V bus rails (18-32 V typical) because its 38 V rating provides 6 V of headroom above the upper bus limit and its 1.2 A capacity handles small PLC sensor banks. The fixed 3.3 V output directly powers 3.3 V analog Micro controllers and HART modems. Compared with a discrete switching controller plus external MOSFET, the integrated LT3971 shrinks the BOM by 60% and eliminates most PCB layout risk. Estimated efficiency at VIN=24 V, VOUT=3.3 V, IOUT=1 A is ~70%; the exposed pad must be soldered to at least 0.5 sq. inch of copper to keep junction temperature below 100 °C in a sealed IP65 enclosure.
Được đề xuất
Always-On IoT Housekeeping Supplies
The LT3971EMSE-3.3#PBF suits always-on IoT housekeeping because its 2.8 µA Burst Mode quiescent current extends battery life by 5-10× versus a fixed-frequency PFM regulator. At VIN=6 V (two alkaline cells), the 1.2 A output can supply a low-power wireless MCU plus a low-duty-cycle sensor, while drawing under 5 µA when the load is asleep. The PGOOD flag can wake the host MCU only when the rail is healthy, reducing false wake events. The 10-MSOP exposed-pad footprint occupies 9 mm² of PCB, leaving room for a CR2032 coin-cell backup rail on the same board.
Được đề xuất
Distributed Point-of-Load Regulation in Telecom Systems
The LT3971EMSE-3.3#PBF supports telecom point-of-load regulation because its 38 V input handles -48 V telecom rails through a front-end preregulator that drops to 12 V or 24 V, and its 2 MHz switching frequency enables a 4.7 µH inductor that fits behind a BGA ASIC. The fixed 3.3 V output directly powers DSPs, FPGAs, and clock buffers in line cards. The 700 nA shutdown current allows sleep-mode current budgets to be met when the line card is idle, while the soft-start pin avoids inrush into hot-swapped backplanes. Multiple LT3971s can be paralleled with phased switching to reduce input ripple.
Được đề xuất
Portable Test and Measurement Instrumentation
The LT3971EMSE-3.3#PBF fits portable battery-powered test gear because its 2.8 µA quiescent current preserves battery life during standby, while its 1.2 A peak output handles the inrush of a brief measurement cycle. The fixed 3.3 V output powers low-power ADCs, op-amps, and display drivers in handheld multimeters and oscilloscope probes. Compared with a SEPIC or flyback topology, the LT3971's simple buck configuration needs only one inductor and one Schottky diode, reducing BOM cost and PCB area by 40% - critical for hand-held form factors.
Được đề xuất
Solar-Powered Remote Sensor Nodes
The LT3971EMSE-3.3#PBF suits solar-powered remote sensors because its 38 V input tolerates open-circuit voltages of 30 V from small 72-cell solar panels, while its 100% duty-cycle operation maximizes energy harvest as the panel voltage droops during cloud events. The fixed 3.3 V output directly powers LoRa or NB-IoT modems and environmental sensors. Estimated battery life at 1% duty cycle (10 mA average load, 2.8 µA quiescent) exceeds 5 years on a 2.6 Ah LiSOCl2 pack, eliminating field service calls. The exposed pad allows operation at +85 °C ambient without thermal shutdown.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho LT3971EMSE-3.3#PBF — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | LT3971EMSE-3.3#TRPBF | LT3971EMSE#PBF | LT3971EMSE-5#PBF | LT3971IMSE-3.3#PBF | LT3971HMSE-3.3#PBF |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 10-MSOP with Exposed Pad (MSE) | 10-MSOP with Exposed Pad (MSE) - same | 10-MSOP with Exposed Pad (MSE) - same | 10-MSOP with Exposed Pad (MSE) - same | 10-MSOP with Exposed Pad (MSE) - same | 10-MSOP with Exposed Pad (MSE) - same |
| Output Voltage | 3.3 V fixed | 3.3 V fixed | 1.19 V to 30 V adjustable | 5 V fixed | 3.3 V fixed | 3.3 V fixed |
| Maximum Output Current | 1.2 A | 1.2 A | 1.2 A | 1.2 A | 1.2 A | 1.2 A |
| 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 |
| Quiescent Current | 2.8 µA (Burst Mode) | 2.8 µA | 2.8 µA | 2.8 µA | 2.8 µA | 2.8 µA |
| Switching Frequency | Up to 2 MHz | Up to 2 MHz | Up to 2 MHz | Up to 2 MHz | Up to 2 MHz | Up to 2 MHz |
| Temperature Grade | E: -40 °C to +125 °C | E: -40 °C to +125 °C | E: -40 °C to +125 °C | E: -40 °C to +125 °C | I: -40 °C to +125 °C (industrial) | H: -40 °C to +150 °C (military) |
Bảo phân biệt quan trọng
- Fixed 3.3 V output eliminates external feedback divider (vsLT3971EMSE#PBF)
- Same MSE package as 5 V sibling - drop-in on 5 V designs (vsLT3971EMSE-5#PBF)
- 38 V input withstands 24 V industrial and 12 V automotive load-dump (vsLT3971IMSE-3.3#PBF)
Ghi chú thiết kế
Place the input bulk capacitor (≥ 10 µF ceramic plus optional 47 µF aluminum polymer) within 5 mm of the VIN pin to minimize switching noise injection into the input rail. The BST capacitor (≥ 100 nF) must sit within 2 mm of the BST pin with a short, wide trace to SW. The exposed pad must be soldered to a continuous copper pour of at least 0.5 sq. inch on the top layer plus thermal vias to inner ground planes to keep junction temperature below 110 °C at full load.
Estimated: At VIN = 12 V, VOUT = 3.3 V, IOUT = 1 A, the LT3971EMSE-3.3#PBF dissipates roughly (12 - 3.3) × 1 × (1 - 0.82) ≈ 1.6 W (assuming 82% efficiency). With the MSOP-10 exposed-pad thermal resistance of about 45 °C/W on a JEDEC 4-layer test board, junction rise is ~72 °C above ambient, giving a max ambient of about 53 °C at the 125 °C limit. For higher VIN or higher load, expand the copper pour or use multiple vias under the exposed pad.
Do not leave the SS pin floating - it must have a capacitor to ground (≥ 1 nF) or soft-start will not function and inrush current can trip the input fuse. The EN pin has an accurate 1 V threshold; if left floating it may drift into the indeterminate region and cause unreliable startup. Tie EN to VIN through a 100 kΩ resistor when always enabled. Avoid using output capacitors with ESR below 5 mΩ to prevent subharmonic instability in current-mode control.
Thông tin tuân thủ
#PBF suffix indicates Pb-free finish per RoHS. REACH compliance per Analog Devices material declarations. Not AEC-Q100 qualified - for automotive designs requiring AEC-Q100, use a Q100-graded part. Halogen-free status not stated in the verified data.
