LM3481QMMX/NOPBQ1 - 48V Boost/SEPIC/Flyback Controller | TI
MPN： LM3481QMMX/NOPBQ1 ✓ 啟用中LM3481QMMX/NOPBQ1 概覽
A switching controller is the brain of a switched-mode power supply (SMPS): it drives an external low-side N-FET as the primary switch, regulating the output through current-mode PWM control. As a controller (rather than a monolithic regulator), the LM3481-Q1 lets designers scale output power freely by choosing an external MOSFET, inductor, and sense resistor, making it suitable from a few watts up to tens of watts.
Key features include current-mode PWM control with 85% maximum duty cycle, programmable switching frequency (set by a single resistor, up to 1MHz) enabling small magnetics and fast transient response, an internal 5V regulated gate-driver rail for the external N-FET, cycle-by-cycle current limit, thermal shutdown, and a frequency-foldback/soft-start-friendly architecture that simplifies startup in boost applications. Wide 2.97V to 48V VIN supports automotive 12V and 24V rails with load-dump headroom.
The LM3481-Q1 is fabricated on a proven analog process, qualified to AEC-Q100 Grade 1 (-40C to +125C ambient), making it suitable for under-hood and in-cabin automotive systems. The VSSOP-10 package has a low profile of 1mm and small footprint for space-constrained designs. Output voltage is set by a feedback divider; the FB reference threshold is specified in the datasheet.
Typical applications include automotive LED headlamp and backlight drivers, on-board charger auxiliary supplies, infotainment display boost rails, industrial 24V-to-higher-voltage boost converters, and isolated or non-isolated flyback auxiliaries.
Design tip: keep the switch-node and gate-drive loops tight, and size the current-sense resistor for the desired cycle-by-cycle limit while accounting for its power dissipation.
直接替換替代品，適用於 LM3481QMMX/NOPBQ1 — 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： LM3481QMMX/NOPBQ1 （相同外形與佔位） — 差異在於 Package, RoHS Status, Topology.
LM3481QMM/NOPB
✅ 直接替換📋 參考替代品（不在目錄中）
LM3481MMX/NOPB
✅ 直接替換聯絡詢價
查看資料表 →LM3481QMY/NOPB
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LM5117QMHX/NOPB
⚡ 相同封裝✗ 缺貨
$3.72 / 單位
查看資料表 →MAX668AUB
⚡ 相同封裝 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LM3481QMMX/NOPBQ1 最大額定值與電氣特性
| 拓撲 | Boost, SEPIC, Flyback |
| Control Method | Current Mode PWM |
| 輸入電壓範圍 | 2.97 V to 48 V |
| Output Polarity | Positive |
| Switch Type | External Low-Side N-Channel FET |
| Maximum Switching Frequency | 1 MHz (resistor programmable) |
| Maximum Duty Cycle | 85% |
| 輸出數量 | 1 |
| Automotive Qualification | AEC-Q100 Grade 1 |
| 工作溫度 | -40C to +125C |
| 封裝 | 10-VSSOP / 10-MSOP (3.00mm width) |
| 安裝類型 | Surface Mount |
| Packaging | Tape & Reel (TR) |
| Protection Features | Cycle-by-cycle current limit, thermal shutdown |
| RoHS 狀態 | Compliant (NOPB / lead-free) |
| Gate Driver Supply | Internal regulated VCC for N-FET drive |
LM3481QMMX/NOPBQ1 腳位配置
| 腳位 1 | SW — Switch node connection to external N-FET drain |
| 腳位 2 | VCC — Internal regulated supply output for gate drive |
| 腳位 3 | GND — Ground reference |
| 腳位 4 | FB — Feedback input from output voltage divider |
| 腳位 5 | COMP — Loop compensation network connection |
| 腳位 6 | FREQ — Switching frequency set resistor |
| 腳位 7 | SS — Soft-start capacitor connection |
| 腳位 8 | VIN — Input supply, 2.97V to 48V |
| 腳位 9 | CS — Current sense input for cycle-by-cycle limit |
| 腳位 10 | AGND — Analog ground for controller reference |
典型應用
LM3481QMMX/NOPBQ1 適用於 6 應用s: Automotive LED Headlamp Driver, Automotive Infotainment Display Boost Rail, On-Board Charger Auxiliary Supply, Industrial 24V Boost Converter, SEPIC Battery-Power Conversion, Gateway and Telematics Power Stage.
Automotive LED Headlamp Driver
The LM3481-Q1 fits automotive LED headlamp boost stages because its 2.97V to 48V VIN absorbs load-dump transients and its AEC-Q100 Grade 1 rating covers the -40C to +125C engine-bay environment. Operating in boost mode with an external low-side N-FET, it steps 12V up to the LED string voltage; cycle-by-cycle current limit plus the current-mode loop enable constant-current LED drive, and 1MHz-capable operation keeps the inductor small for lamp housings.
推薦
Automotive Infotainment Display Boost Rail
Infotainment panels require a stable 12V-to-18V or higher boost rail from the car battery. The LM3481-Q1 drives an external MOSFET, allowing designers to scale output current to the display backlight and logic load without being limited by an internal switch. Its current-mode PWM with 85% duty cycle and resistor-programmable frequency (up to 1MHz) lets the converter sit above the AM band to ease EMI filtering, while AEC-Q100 Grade 1 qualification meets cabin temperature requirements.
推薦
On-Board Charger Auxiliary Supply
EV on-board chargers need an auxiliary rail powered from the high-voltage DC link. The LM3481-Q1's 48V maximum VIN and flyback topology support make it a fit for tapping intermediate 12V/24V/48V buses to generate isolated or non-isolated auxiliary supplies for gate drivers and contactors. Using an external N-FET lets the design handle tens of watts, and thermal shutdown plus cycle-by-cycle current limit provide robust fault handling in high-voltage environments.
推薦
Industrial 24V Boost Converter
Industrial control and instrumentation running from 24V buses frequently need 36V to 48V rails for sensors, OLED displays, or op-amp supplies. The LM3481-Q1 boosts from 24V with ample headroom, and its wide VIN also tolerates 12V fallback operation. The current-mode loop simplifies loop compensation with ceramic output capacitors, and the VSSOP-10 footprint keeps the controller overhead small on dense industrial PCBs.
推薦
SEPIC Battery-Power Conversion
For battery-powered equipment where the input varies above and below the required output, the LM3481-Q1 SEPIC configuration regulates a fixed output from a 3-cell to 4-cell series battery. Its low 2.97V minimum VIN supports deeply discharged cells, while the coupled-inductor SEPIC topology with an external low-side FET delivers efficient step-up/step-down conversion. Programmable frequency up to 1MHz permits small coupled inductors in portable and robotics designs.
推薦
Gateway and Telematics Power Stage
Automotive gateway and telematics modules generate 5V or 8V intermediate rails from a fluctuating 9V to 16V battery input. The LM3481-Q1 in boost mode with pre-boost for cold crank keeps downstream bucks such as the LM5176 or TPS65 family powered during voltage dips. Its small VSSOP-10 package and high switching frequency reduce board area, and AEC-Q100 Grade 1 qualification supports the telematics unit's under-dash temperature profile.
推薦
推薦產品摘要
工程參考資料，適用於 LM3481QMMX/NOPBQ1 — 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 | LM3481QMM/NOPB | LM3481MMX/NOPB | MAX668AUB |
|---|---|---|---|---|
| Package | VSSOP-10 (DGS) | VSSOP-10 (DGS) - same | VSSOP-10 (DGS) - same | MSOP-10 - same footprint, different pinout |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices |
| Input Voltage Range | 2.97 V to 48 V | 2.97 V to 48 V | 2.97 V to 48 V | 3 V to 28 V |
| Topologies | Boost, SEPIC, Flyback | Boost, SEPIC, Flyback | Boost, SEPIC, Flyback | Boost, SEPIC, Flyback |
| Max Switching Frequency | 1 MHz | 1 MHz | 1 MHz | 500 kHz |
| Automotive Qualification | AEC-Q100 Grade 1 | AEC-Q100 Grade 1 | Not automotive qualified | Not automotive qualified |
| Control Method | Current Mode PWM | Current Mode PWM | Current Mode PWM | Current Mode PWM |
| Pin-to-Pin Drop-In | N/A (reference) | Yes - identical | Yes - identical | No - redesign required |
主要差異化特點
- AEC-Q100 Grade 1 automotive qualification (對比LM3481MMX/NOPB)
- Wider 48V VIN than cross-brand MSOP-10 controllers (對比MAX668AUB)
- Scalable output power via external FET (對比LM5117QMHX/NOPBQ1)
設計說明
Keep the power loop (input cap, external N-FET, inductor, sense resistor) as tight as possible; the SW node carries high dv/dt and radiates. Route the CS sense line differentially to the sense resistor Kelvin contacts to avoid false current-limit trips from switch-node ringing. Place the FREQ, FB, and COMP components close to their pins with a solid analog ground return to pin 10.
In boost converters the output is connected to VIN through the inductor when the FET fails short, so add reverse protection or a fuse if the load must be protected. Ensure VCC (internal regulator) has the recommended decoupling capacitor or gate drive collapses at high frequency. Never exceed the 48V absolute maximum VIN - automotive load dump requires upstream TVS suppression.
Because this is a controller, thermal design centers on the external MOSFET and sense resistor, not the VSSOP-10 itself. Size the FET for RMS current and switching loss at your frequency; at 1MHz, switching loss dominates, so choose a FET with low Qgd. Verify sense resistor power: P = I^2 x R, and derate at 125C ambient for AEC-Q1 designs.
合規資訊
NOPB suffix indicates No Pb (lead-free) per TI ordering nomenclature. AEC-Q100 Grade 1 per TI LM3481-Q1 product page. REACH and halogen-free status not stated in provided data.
