MP2451DJ-LF-P - 600mA, 36V, 2MHz Step-Down Converter | MPS
MPN： MP2451DJ-LF-P ✓ 啟用中MP2451DJ-LF-P 概覽
What is a buck (step-down) switching regulator? A buck converter is a type of switched-mode power supply (SMPS) that efficiently steps a higher DC input voltage down to a lower DC output voltage. It belongs to the DC-DC converter hierarchy -> power management IC -> semiconductor. Compared to linear regulators, buck converters achieve much higher efficiency (often above 90 %) at the cost of output ripple and the need for an external inductor and capacitors. The MP2451 integrates the high-side MOSFET and control loop into one IC, simplifying PCB design and shrinking the BOM.
Key features include a wide 3.3 V to 36 V input range (well-suited to automotive 12 V/24 V buses), 600 mA continuous output current, 2 MHz fixed switching frequency (allowing small ceramic output capacitors and a compact inductor), internal compensation, internal soft-start, cycle-by-cycle over-current protection, and thermal shutdown. The TSOT-23-6 footprint is one of the smallest 600 mA synchronous-buck packages available, enabling high power density in space-constrained designs.
Technically, the MP2451 uses peak current-mode control with internal slope compensation, providing stable operation across duty cycles and easy loop compensation. The 2 MHz switching frequency pushes the fundamental and harmonics well above the AM broadcast band, simplifying EMI compliance in automotive and consumer products. The high-side P-channel MOSFET is fully integrated, eliminating the need for an external Schottky diode and reducing conduction loss.
Typical applications include automotive infotainment and instrument-cluster rails, distributed 5 V/3.3 V supplies from a 12 V or 24 V bus, USB/wall-adapter powered portable electronics, point-of-load conversion for microcontrollers and sensors, and battery-powered industrial equipment. The 36 V input tolerance also tolerates load-dump transients seen in automotive environments.
When designing with the MP2451, choose a low-DCR shielded inductor in the 2.2 uH to 4.7 uH range and use X7R ceramic input/output capacitors rated for the working voltage. Always observe the absolute-maximum VIN of 38 V and provide adequate PCB copper area for thermal dissipation at high VIN-VOUT differentials.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, giving an engineer a single decision-ready view of the MP2451DJ-LF-P.
直接替換替代品，適用於 MP2451DJ-LF-P — 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： MP2451DJ-LF-P （相同外形與佔位） — 差異在於 Output Voltage Range, Package, Quiescent Current (Shutdown), RoHS Status, Soft Start.
MP2451DJ-LF-Z
✅ 直接替換✓ 有庫存
$0.2953 / 單位
查看資料表 →MP2451DT-LF-P
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MP2451DT-LF-Z
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MP2451DJ-LF-P 最大額定值與電氣特性
| 拓撲 | Buck (Step-Down) Switching Regulator |
| 輸入電壓範圍 | 3.3 V to 36 V |
| Absolute Maximum VIN | 38 V |
| 輸出電壓範圍 | 0.8 V to VIN (adjustable) |
| Output Current | 600 mA continuous |
| 切換頻率 | 2 MHz typical |
| Quiescent Current (Shutdown) | 1 uA |
| Control Method | Current-mode PWM |
| MOSFET | Internal high-side |
| 同步整流器 | No (non-sync, external diode) |
| 工作溫度範圍 | -40 C to +125 C (junction) |
| 封裝 | SOT-23-6 Thin (TSOT-23-6) |
| 安裝類型 | Surface Mount |
| RoHS 狀態 | Compliant (LF suffix) |
| Lead-Free Finish | Yes (LF suffix) |
| Enable / Shutdown | Yes |
| 軟啟動 | Internal |
| Protection Features | Over-current, thermal shutdown |
MP2451DJ-LF-P 腳位配置
| 腳位 1 | SW — Switching node - connects to external inductor and Schottky diode cathode |
| 腳位 2 | IN — Input supply voltage (3.3 V to 36 V) |
| 腳位 3 | EN — Enable input; pull high to turn on, low for 1 uA shutdown |
| 腳位 4 | FB — Feedback voltage input; 0.8 V reference, set VOUT with resistor divider |
| 腳位 5 | GND — Ground return |
| 腳位 6 | BST — Bootstrap; connect a small flying cap between BST and SW for high-side drive |
典型應用
MP2451DJ-LF-P 適用於 6 應用s: Automotive 12 V / 24 V Point-of-Load, Industrial 24 V Sensor / PLC Rails, Portable Battery-Powered Devices, USB / Wall-Adapter Powered Accessories, E-Metering and Energy Harvesting, LED Lighting Drivers.
Automotive 12 V / 24 V Point-of-Load
The MP2451DJ-LF-P fits automotive point-of-load conversion directly because its 3.3 V to 36 V input and 38 V abs-max survive cold-crank and load-dump on a 12 V or 24 V automotive bus, while its 600 mA output comfortably powers an MCU or sensor cluster. Placed after a front-end filter, the part steps the bus down to a clean 3.3 V or 5 V rail using a 2.2 uH shielded inductor and X7R ceramic caps, and the 2 MHz switching frequency keeps EMI above the AM band. Compared with an LDO, the buck topology keeps efficiency above 90 percent, which is critical for body-control modules that sit on the battery rail continuously.
推薦
Industrial 24 V Sensor / PLC Rails
The MP2451DJ-LF-P is well matched to industrial 24 V PLC and sensor modules because its 36 V input tolerates the worst-case rectified 24 V bus including transients, and its 600 mA output can run multiple analog and digital loads in parallel. Designed in with current-mode control and internal compensation, the loop is stable with ceramic output capacitors, eliminating bulky electrolytics on crowded PLC boards. The 1 uA shutdown quiescent current is valuable for remote sensors that spend most of their life asleep between measurements, and the wide -40 C to +125 C thermal rating supports outdoor enclosures and factory-floor temperature swings.
推薦
Portable Battery-Powered Devices
The MP2451DJ-LF-P suits portable, battery-powered products thanks to its 1 uA shutdown quiescent current and high efficiency at light load, which together extend runtime on a single-cell Li-ion or 2x AA pack. Its 2 MHz switching frequency enables a tiny 2.2 uH inductor and small ceramic capacitors, freeing board area for the rest of a handheld design. Compared with an LDO at the same load, the buck typically saves several mW of dissipation, directly translating to longer standby time. Designers should add an input Schottky or fuse for reverse-battery and hot-plug protection typical in consumer portable designs.
推薦
USB / Wall-Adapter Powered Accessories
The MP2451DJ-LF-P is ideal for USB-powered or wall-adapter-powered accessories because its 3.3 V minimum input starts up directly from a 5 V USB rail, and its 36 V tolerance allows the same board to be powered from unregulated 12 V adapters without redesign. At 2 MHz the fundamental ripple is far above typical audio or data-acquisition bandwidth, so the post-buck noise floor is set by the load rather than the regulator. The TSOT-23-6 footprint keeps the converter small enough to sit next to a USB-C connector, making it a clean choice for dongles and docking stations.
推薦
E-Metering and Energy Harvesting
The MP2451DJ-LF-P fits e-metering and energy-harvesting front ends because its wide 3.3 V to 36 V input accepts rectified mains or solar inputs, and its 1 uA shutdown current preserves battery-backed RTC and metrology circuits between active windows. The 2 MHz switching frequency is well above the metrology ADC sampling band, simplifying post-filtering, and current-mode control provides excellent line transient response for load steps caused by relay switching in smart meters. Designers should pair the MP2451 with a low-Iq MCU supervisor and a precision metrology ADC for a complete energy-measurement subsystem.
推薦
LED Lighting Drivers
The MP2451DJ-LF-P is a good fit for driving constant-current LED strings from a 12 V or 24 V bus because its 600 mA output can power multiple high-brightness LEDs in series and its adjustable output from 0.8 V upward allows a simple sense-resistor feedback loop. The 36 V input withstands the inductive kick of long LED wiring harnesses, and the 2 MHz switching frequency is well above the human flicker-fusion threshold, producing visually flicker-free light even at low dimming levels. Thermal performance in the TSOT-23-6 package is sufficient for LED currents up to about 350 mA continuous without external heatsinking.
推薦
推薦產品摘要
工程參考資料，適用於 MP2451DJ-LF-P — 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 | MP2451DJ-LF-Z | MP2451DT-LF-P | MP2451DT-LF-Z |
|---|---|---|---|---|
| Package | TSOT-23-6 | TSOT-23-6 - same | TSOT-23-8 | TSOT-23-8 |
| Brand | Monolithic Power Systems | Monolithic Power Systems | Monolithic Power Systems | Monolithic Power Systems |
| Input Voltage Range | 3.3 V to 36 V | 3.3 V to 36 V | 3.3 V to 36 V | 3.3 V to 36 V |
| Output Current | 600 mA | 600 mA | 600 mA | 600 mA |
| Switching Frequency | 2 MHz | 2 MHz | 2 MHz | 2 MHz |
| Output Voltage Range | 0.8 V to VIN | 0.8 V to VIN | 0.8 V to VIN | 0.8 V to VIN |
| Shutdown Iq | 1 uA | 1 uA | 1 uA | 1 uA |
| Synchronous Rectifier | No (external Schottky) | No (external Schottky) | No (external Schottky) | No (external Schottky) |
| Pin/Package Variant | TSOT-23-6, P reel | TSOT-23-6, Z reel | TSOT-23-8, P reel | TSOT-23-8, Z reel |
主要差異化特點
- Widest input range in the small TSOT-23-6 buck class (對比MP2459GJ-P)
- Smallest package for 600 mA at 36 V (對比MP2451DT-LF-P)
- Very low 1 uA shutdown Iq (對比MP2451DT-LF-P)
設計說明
Place the input ceramic capacitor (>= 4.7 uF X7R), the Schottky diode, and the output inductor as close as possible to the SW and GND pins. The exposed pad on the TSOT-23-6 must be soldered to a ground copper pour of at least 50 mm^2 to keep the junction temperature within the -40 C to +125 C rating. Keep the FB trace away from the SW node and the inductor to avoid noise coupling into the feedback loop.
At VIN = 24 V, VOUT = 5 V, IOUT = 600 mA, the dissipation is about (24 - 5) V x 0.6 A x (1 - efficiency) plus switching loss. Estimated: with ~90% efficiency the IC dissipation is around 1.1 W, which the TSOT-23-6 can handle only with a substantial copper pour or forced airflow. Drop the input voltage or reduce load at high VIN to stay within thermal limits.
Do not omit the BST flying capacitor between BST and SW; without it the high-side MOSFET will not turn on fully and efficiency drops sharply. Do not drive large MOSFET gates from BST; it is rated only for the internal high-side driver. Always respect the 38 V absolute-max VIN, including transients; add a TVS or input fuse if the source is a long automotive harness.
The fixed 2 MHz switching frequency keeps fundamental emissions above the AM broadcast band, but switching-node ringing can still violate CISPR 25 in sensitive automotive designs. Add a small RC snubber (~ 2 to 10 ohm in series with 100 pF to 1 nF) across the Schottky diode or use a shielded inductor to damp SW-node ringing and reduce radiated emissions.
合規資訊
LF suffix indicates lead-free / RoHS compliant finish per MPS product page. Industrial-grade temperature range; not AEC-Q100 qualified - choose an automotive-qualified MPS part for safety-critical designs. Halogen-free status not explicitly stated in the verified data - marked unknown.
