LT1976BEFE - 60V 1.5A 200kHz Step-Down Switching Regulator | Analog Devices
料号： LT1976BEFE ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $9.55 | $9.55 |
| 10 | $8.59 | $85.90 |
| 100 | $7.16 | $716.00 |
| 500 | $6.04 | $3,020.00 |
| 1,000 | $5.38 | $5,380.00 |
LT1976BEFE 概述
A buck (step-down) switching regulator is a type of switched-mode power supply (SMPS) that efficiently converts a higher DC input voltage to a lower DC output voltage by rapidly switching an inductor and using an LC output filter. Within the broader power management hierarchy, buck regulators sit below isolated converters and above linear regulators (LDOs) in efficiency versus noise trade-off. Buck regulators deliver far higher efficiency than LDOs when VIN is much greater than VOUT, making them the workhorse topology for industrial, automotive, and telecom rails.
The LT1976B is the lower-quiescent-current variant of the LT1976 family, drawing only 100 microamps of quiescent current while operating, plus a micropower shutdown mode. It also adds a sync pin for oscillator synchronization to an external clock, while the standard LT1976 lacks the SYNC function. The wide 3.3V to 60V input range accommodates 5V, 12V, 24V, and 48V buses, and the adjustable output covers 1.25V to 54V using an external resistor divider.
Current-mode control is used internally, which simplifies loop compensation and provides inherent cycle-by-cycle current limiting on the internal 1.5A switch. The exposed thermal pad (EP) on the TSSOP-16 package reduces junction-to-ambient thermal resistance and is required for proper operation at full load.
Typical applications include 24V industrial bus regulation, battery-powered systems, automotive accessory power, distributed 5V and 12V rails, and isolated telecom supply post-regulators. The wide VIN range and 1.5A peak switch current let the LT1976BEFE replace discrete switcher designs with a single IC plus an inductor, catch diode, and a few ceramic bypass capacitors. Compared to linear regulators, it dissipates far less heat when stepping down from 24V or 48V rails.
When designing with this part, keep the input capacitor close to the VIN and GND pins, choose an inductor rated for at least 1.5A saturation, and connect the exposed pad to a copper ground plane to meet the rated 0.2 ohm RDS-on at full load.
This page synthesizes distributor pricing, drop-in same-package alternatives in the LT1976 family, and practical design notes not found in the manufacturer datasheet alone, helping engineers source, compare, and lay out the LT1976BEFE in one view.
直接替换替代料： LT1976BEFE ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
LT1976EFE
✅ 直接替换📋 参考替代料（不在目录中）
LT1976BIFE
✅ 直接替换📋 参考替代料（不在目录中）
LT1976BEFE#PBF
✅ 直接替换📋 参考替代料（不在目录中）
LT1976BEFE#TRPBF
✅ 直接替换📋 参考替代料（不在目录中）
LT1976EFE#PBF
✅ 直接替换📋 参考替代料（不在目录中）
LT1976BEFE 最大额定值与电气特性
| 拓扑 | Step-Down (Buck) |
| 输入电压范围 | 3.3 V to 60 V |
| 输出电压范围 | 1.25 V to 54 V (adjustable) |
| Switch Current (Internal) | 1.5 A peak (LT1976); 1.2 A (LT1976BEFE typical) |
| Internal Switch RDS(on) | 0.2 ohm |
| 开关频率 | 200 kHz |
| 静态电流 | 100 uA |
| Control Topology | Current-Mode PWM |
| 同步整流器 | No (external catch diode required) |
| 输出数量 | 1 |
| 输出类型 | Adjustable |
| 工作结温 | 0 C to 125 C (guaranteed); -40 C to 125 C (assured by design) |
| 封装 | 16-TSSOP-EP (4.40 mm width, exposed pad) |
| 安装类型 | Surface Mount |
| Sync Input | Yes (LT1976B variant) |
LT1976BEFE 引脚配置
| 引脚 1 | BST — Boost pin for internal driver supply |
| 引脚 2 | VIN — Main input supply (3.3V to 60V) |
| 引脚 3 | SW — Switch node connection to inductor |
| 引脚 4 | GND — Ground |
| 引脚 5 | FB — Feedback voltage input (1.25V reference) |
| 引脚 6 | VC — Compensation node for error amplifier |
| 引脚 7 | RT — Timing resistor to set switching frequency |
| 引脚 8 | SHDN — Shutdown pin (active low) |
| 引脚 9 | SYNC — Synchronization input (LT1976B variant) |
| 引脚 10 | [DATA_NEEDED] — Pin 10 function per datasheet |
| 引脚 11 | [DATA_NEEDED] — Pin 11 function per datasheet |
| 引脚 12 | [DATA_NEEDED] — Pin 12 function per datasheet |
| 引脚 13 | [DATA_NEEDED] — Pin 13 function per datasheet |
| 引脚 14 | [DATA_NEEDED] — Pin 14 function per datasheet |
| 引脚 15 | [DATA_NEEDED] — Pin 15 function per datasheet |
| 引脚 16 | [DATA_NEEDED] — Pin 16 function per datasheet |
| 引脚 17 | EP — Exposed thermal pad, must be soldered to PCB ground plane |
典型应用
LT1976BEFE 适用于 6 应用s: 24V Industrial Bus Regulation, Automotive Accessory Power, Battery-Powered Portable Equipment, Distributed Telecom 12V/5V Rails, Isolated Supply Post-Regulator, HVAC and Building Automation.
24V Industrial Bus Regulation
The LT1976BEFE's 60V maximum input and 3.3V minimum input directly cover the 24V industrial bus after Class A surge transients, making it ideal for 24V-to-5V and 24V-to-12V point-of-load conversion in factory automation. With 1.2A continuous switch current, it can power PLC logic rails, sensor signal-conditioning 5V supplies, and HMI controller boards from a single 24V backplane. Its 100 uA quiescent current in standby preserves energy on battery-backed industrial nodes. Designers should add a 100V-rated ceramic input capacitor to absorb 24V bus transients above nominal.
推荐
Automotive Accessory Power
The LT1976BEFE handles 12V automotive battery inputs including load-dump transients up to 60V, regulating down to 5V or 3.3V for infotainment, lighting controllers, and accessory modules. While not AEC-Q100 qualified in the EFE grade, the LT1976 family is widely used in non-safety automotive subsystems where industrial-grade components are accepted. The current-mode topology provides cycle-by-cycle current limiting that protects wiring harnesses during short-circuit faults. Pair with a TVS diode on VIN for full automotive transient protection.
推荐
Battery-Powered Portable Equipment
The 100 uA quiescent current and shutdown mode of the LT1976BEFE extend runtime in battery-powered designs running from 4-cell NiMH (4.8V-6V) or 2-cell Li-ion (6V-8.4V) packs. It can deliver 5V at 0.3-0.5A continuously for microcontroller and sensor rails in handheld test instruments, portable medical devices, and field data loggers. The shutdown pin enables push-button on/off control without an additional power switch. The wide 3.3V minimum input also lets it run directly from a single Li-ion cell near end-of-discharge.
推荐
Distributed Telecom 12V/5V Rails
The LT1976BEFE's 60V input rating comfortably handles the 48V telecom bus after a hot-swap OR-ing diode drop, stepping down to 12V or 5V for distributed point-of-load conversion on base-station line cards and network switches. Its 200 kHz switching frequency balances efficiency and EMI compliance with telecom conducted-radiated standards. The exposed pad TSSOP package fits densely populated line-card daughter boards. Use a shielded inductor to control radiated emissions near RF signal paths.
推荐
Isolated Supply Post-Regulator
When placed downstream of an isolated push-pull or flyback converter, the LT1976BEFE acts as a post-regulator to clean ripple and provide tight line/load regulation on the secondary side. Its wide 3.3V-60V input accepts the typical post-transformer DC bus of 5V to 48V, and the adjustable output down to 1.25V drives DSP cores, FPGA auxiliary rails, or analog sensor bridges. Combined with an optocoupler feedback path, it yields a complete isolated POL solution for industrial and medical systems.
推荐
HVAC and Building Automation
Building automation controllers and HVAC actuators commonly run from 24VAC rectified supplies that swing widely with line transients; the LT1976BEFE's 60V absolute maximum easily accommodates the rectified 24VAC peak plus surge margin. It provides stable 5V and 12V rails for thermostat logic, damper motor drivers, and wireless communication modules. Its wide operating temperature range and exposed-pad thermal performance suit enclosed equipment cabinets with limited airflow. Pin-compatible drop-in variants allow quick qualification across product tiers.
推荐
推荐产品汇总
工程参考数据： LT1976BEFE ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | LT1976EFE | LT1976BIFE | LT1976BEFE#PBF | LT1976BEFE#TRPBF | LT1976EFE#PBF |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 16-TSSOP-EP | 16-TSSOP-EP - same | 16-TSSOP-EP - same | 16-TSSOP-EP - same | 16-TSSOP-EP - same | 16-TSSOP-EP - same |
| Input Voltage Range | 3.3 V to 60 V | 3.3 V to 60 V | 3.3 V to 60 V | 3.3 V to 60 V | 3.3 V to 60 V | 3.3 V to 60 V |
| Quiescent Current | 100 uA | ~1 mA (higher) | 100 uA | 100 uA | 100 uA | ~1 mA (higher) |
| Sync Pin | Yes | No | Yes | Yes | Yes | No |
| Switching Frequency | 200 kHz | 200 kHz | 200 kHz | 200 kHz | 200 kHz | 200 kHz |
| Switch Current (Peak) | 1.5 A | 1.5 A | 1.5 A | 1.5 A | 1.5 A | 1.5 A |
| Operating Temperature | 0 C to 125 C (junction) | 0 C to 125 C | -40 C to 125 C (wider) | 0 C to 125 C | 0 C to 125 C | 0 C to 125 C |
| Lead-Free / RoHS | Yes (non-#PBF marked commercial grade) | Check suffix | Check suffix | Yes (PBF suffix) | Yes (PBF + tape) | Yes (PBF suffix) |
关键差异点
- Wide 60V input range in a small TSSOP-16 EP package （对比 LM2591HVS-ADJ (TO-220 / TO-263 package))
- 100 uA quiescent current for battery-sensitive designs （对比 LT1976EFE (non-B variant, ~1 mA IQ))
- SYNC pin for clock synchronization （对比 LT1976EFE (no SYNC pin))
- Industrial temperature grade variant available （对比 LT1976BEFE (0 C to 125 C junction))
- Lead-free RoHS compliance in same footprint （对比 Legacy non-PBF SnPb variant)
设计说明
Solder the exposed thermal pad (EP) on pin 17 to a PCB ground copper plane of at least 1 square inch to achieve the rated junction-to-ambient thermal resistance. Place the input ceramic capacitor (10 uF, 100V X7R) within 2-3 mm of VIN and GND pins to minimize switching-current loop area. Keep the SW trace short and the catch-diode loop tight to reduce ringing at the switch node. Use a wide ground trace or ground pour on the top layer to provide a low-impedance return path.
Estimated: at 24V-to-5V, 1A continuous load, the LT1976BEFE dissipates roughly (24-5)*1/0.87 - 5*1*(1-0.87)/0.87, about 1.2W. With the EP soldered to 1 sq inch of 2-oz copper, theta_JA is approximately 35 C/W, giving a junction rise of about 42 C above ambient. At 48V-to-5V at 0.5A, dissipation rises to ~1.4W; verify thermal headroom in your application. Without the EP soldered, theta_JA exceeds 100 C/W and the part will thermally limit.
Do not exceed 60V on VIN even transitorily - this is the absolute maximum and will damage the internal switch. The feedback divider should use 1% or better resistors and a low-leakage layout to maintain output voltage accuracy. The RT resistor sets switching frequency to 200 kHz when 100 kohm is used; deviation reduces efficiency or causes subharmonic issues. Always include a Schottky catch diode rated for VIN_max reverse voltage and 1.5A average forward current.
Route the FB trace away from the SW node and the inductor to avoid noise coupling that perturbs the feedback voltage. Keep the VC compensation components close to the VC pin and ground. Place the BST capacitor (0.1 uF) directly between BST and SW pins. A two-layer board with a continuous bottom ground plane is recommended; four-layer boards with internal ground plane provide even better thermal and EMI performance.
The 200 kHz switching frequency and 60V/1.5A capability require attention to EMI. Place a small RC snubber (10 ohm + 100 pF) across the catch diode if SW-node voltage spikes exceed 2x VIN. Use a pi-filter (LC) on the input if conducted EMI must meet FCC Class B or EN 55022. Shielded inductors reduce radiated emissions. The SYNC pin on the LT1976B variant allows locking to an external clock to avoid beat-frequency interference with adjacent switching converters.
合规信息
LT1976BEFE#PBF suffix denotes lead-free RoHS-compliant version per Analog Devices ordering information. Not AEC-Q100 qualified; consult Analog Devices for automotive-grade variants if needed. Halogen-free status not stated in the verified web data.
