LP2981IM5X-3.0 - 100mA Micropower LDO, 3.0V Fixed | Texas Instruments
MPN: LP2981IM5X-3.0 ✓ Hoạt độngLP2981IM5X-3.0 Tóm tắt
What is an LDO (Low-Dropout) linear regulator? An LDO is a type of linear voltage regulator that maintains a stable output voltage even when the input-to-output voltage headroom (dropout) approaches a very small value, often below 200 mV. LDOs sit within the broader voltage regulator family -> power management IC category -> semiconductor hierarchy. Unlike switching regulators, LDOs add no switching noise but dissipate VIN-VOUT x IOUT as heat. They are typically chosen for noise-sensitive analog and RF rails where cleanness matters more than efficiency.
Key features include a 3.0 V fixed output (other voltages available in the LP2981 family), ultra-low quiescent current for standby efficiency, internal current-limit and thermal-shutdown protection, and a stable output with low-ESR ceramic capacitors as small as 1 uF. The new-chip revision (post-NSC) supports an extended 2.5V to 16V input range and ±1% output accuracy across the load/temperature range, while the legacy variant supports VIN to a lower maximum.
Typical applications include powering microcontrollers and MCUs from a 5V or higher rail, USB peripherals, low-power wireless sensor nodes, handhelds, IoT endpoints, and post-DCDC regulation where a quiet, accurate 3.0V rail is needed after a switching pre-regulator. The SOT-23-5 footprint suits space-constrained PCB layouts.
When designing with this device, keep VIN-VOUT dropout margin modest and use a 1 uF or larger ceramic output capacitor with low ESR to ensure regulator stability. Mount the device with adequate copper to share heat; at 100 mA full load with VIN=5V the dissipation is around 200 mW, comfortably inside the SOT-23-5 thermal envelope.
This page synthesizes current distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho LP2981IM5X-3.0 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
LP2981IM5X-3.0/NOPB
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LP2981AIM5X-3.0/NOPB
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LP2981-33DBVR
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
NCP4586DSQ30T1G
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LP2981IM5X-3.0 Tỷ lệ tối đa & tính chất điện
| Kiểu đầu ra | Fixed |
| Nominal Output Voltage | 3.0 V |
| Điện áp tối đa đầu ra | 100 mA |
| Input Voltage Range (New Chip) | 2.5 V to 16 V |
| Output Accuracy | ±1% (new chip, across line/load/temp) |
| Output Voltage Range (Family) | 1.2 V to 5.0 V (new chip) |
| Nhiệt độ hoạt động | -40 C to +125 C |
| Hộp | SOT-23-5 (DCK) |
| Kiểu lắp đặt | Surface Mount |
| Output Capacitor | Ceramic, low-ESR, ≥1 uF |
| Protection Features | Current limit, thermal shutdown |
| Trạng thái RoHS | Compliant |
| N Nap kích hoạt | No (fixed output variant) |
Cấu hình chân LP2981IM5X-3.0
| Chân 1 | VIN — Input supply voltage (2.5V to 16V new chip) |
| Chân 2 | GND — Ground reference |
| Chân 3 | ON/OFF — Shutdown input (logic low disables output) |
| Chân 4 | NC — Not connected (per datasheet) |
| Chân 5 | VOUT — Regulated 3.0V output |
Ứng dụng tiêu biểu
LP2981IM5X-3.0 phù hợp cho 6 Áp dụngs: Microcontroller Power Supply, USB Peripherals and Low-Voltage Logic, Battery-Powered IoT Sensor Nodes, Post-Switching-Regulator Ripple Filter, Handheld and Portable Instruments, Industrial Sensor and Field Wiring.
Microcontroller Power Supply
The LP2981IM5X-3.0 produces a fixed 3.0 V rail ideal for low-power MCUs such as those in the TI MSP430 and NXP Kinetis families. Its micropower quiescent current reduces standby drain in always-on designs, while 100 mA of headroom covers MCU plus support peripherals. The TI LP2981-N datasheet confirms ±1% accuracy and stable operation with a 1 uF ceramic output cap. Designers commonly place the LP2981IM5X-3.0 between a 5 V system rail or Li-ion battery and the MCU's VDD pin to obtain a clean, low-noise supply. Unlike a switching pre-regulator, it adds no ripple to the 3.0 V rail at the cost of VIN-VOUT heat dissipation.
Được đề xuất
USB Peripherals and Low-Voltage Logic
USB peripherals typically require a tightly regulated 3.0 V or 3.3 V rail from a 5 V VBUS source. The LP2981IM5X-3.0 is well matched because its 16 V input tolerance can absorb VBUS transients, and the 100 mA current limit covers most low-power HID and CDC devices. According to the TI LP2981-N datasheet, the part is stable with 1 uF ceramics, simplifying the BOM for cost-sensitive USB dongles. Place the LDO at the VBUS input with input filtering for ESD suppression, and use a 1 uF X5R output cap for transient response.
Được đề xuất
Battery-Powered IoT Sensor Nodes
IoT endpoints powered by Li-ion, LiFePO4, or two-AA cells benefit from the LP2981IM5X-3.0's micropower Iq, which extends standby time significantly compared to larger 100-150 mA LDOs. The 2.5 V minimum input (new chip) keeps the regulator in regulation down to the battery cut-off, ensuring the radio and sensor IC see a stable 3.0 V rail. As the TI LP2981-N datasheet notes, the regulator remains stable with very small ceramic output capacitors, making it ideal for compact sensor modules. Pair with a Bluetooth Low Energy or sub-GHz radio that accepts a 3.0 V supply.
Được đề xuất
Post-Switching-Regulator Ripple Filter
When a switching DC-DC converter provides system power but downstream analog or RF blocks need a quieter rail, the LP2981IM5X-3.0 acts as a post-filter stage. Its high PSRR at low frequencies cleans up the residual ripple from the upstream buck converter, and the fixed 3.0 V output simplifies the analog supply tree. According to the TI LP2981-N datasheet, the small SOT-23-5 footprint allows placement right next to the noise-sensitive IC, minimizing PCB trace-induced noise pickup. Common companions are low-dropout LDOs used after buck converters for mixed-signal SoCs.
Được đề xuất
Handheld and Portable Instruments
Battery-powered test gear, medical handhelds, and barcode scanners often stack a 3.0 V analog rail above a 5V or 12V battery. The LP2981IM5X-3.0 provides a fixed 3.0 V rail with ±1% accuracy, which is critical for ADC reference nodes and sensor excitation. According to the TI LP2981-N datasheet, the thermal-shutdown protection prevents field failures in enclosed handhelds where ambient temperature may rise. Designers often pair the LDO with a low-current instrumentation amplifier on the same 3.0 V rail.
Được đề xuất
Industrial Sensor and Field Wiring
In industrial 24 V sensor loops, a front-end protection block drops the voltage before delivering it to a low-voltage 3.0 V analog or digital section. The LP2981IM5X-3.0 with up to 16 V input tolerance accepts a pre-regulated intermediate rail and produces a fixed 3.0 V for downstream ICs. Per the TI LP2981-N datasheet, the device includes thermal shutdown and current limit, which help the design survive sensor short-circuit faults on the field side. Pair with TVS protection on the field wiring.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho LP2981IM5X-3.0 — 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 | LP2981IM5X-3.0/NOPB | LP2981AIM5X-3.0/NOPB | LP2981-33DBVR | NCP4586DSQ30T1G |
|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | onsemi |
| Package | SOT-23-5 (DCK) | SOT-23-5 (DCK) | SOT-23-5 (DCK) | SOT-23-5 (DBV) | SOT-23-5 (5-pin) |
| Output Voltage | 3.0 V | 3.0 V | 3.0 V | 3.3 V | 3.0 V |
| Output Current | 100 mA | 100 mA | 100 mA | 100 mA | 150 mA |
| RoHS / Lead-Free | Yes | Yes (NOPB) | Yes (NOPB) | Yes | Yes |
| Lifecycle Status | Active | Active | Active | Active | Active |
Bảo phân biệt quan trọng
- Micropower quiescent current for battery applications (vsNCP4586DSQ30T1G)
- Higher input voltage tolerance (new chip) (vsLP2981-33DBVR)
- Wide output voltage options in same family (vsLP2981AIM5X-3.0/NOPB)
Ghi chú thiết kế
Ensure VIN-VOUT dropout margin is respected: at 100 mA full load the LP2981IM5X-3.0 exhibits typical dropout of a few hundred mV (exact value marked [DATA_NEEDED] in the spec list). For a 3.0V output from a 5V rail this gives ample margin, but for low-headroom sources verify the worst-case line/load condition. Adding a small input RC filter (10 ohm + 1 uF) reduces switching noise injection from upstream rails.
Estimated: at VIN=5V, VOUT=3.0V and IOUT=100 mA, dissipation is roughly (5V - 3.0V) * 0.1A = 200 mW. The SOT-23-5 package has a theta_JA around 200 C/W on a standard JEDEC test board, producing an estimated 40 C junction rise above ambient - comfortably inside the 125 C limit. For higher ambient temperatures or hotter rails, increase copper pour around the GND pin to share heat.
Place the 1 uF input and output ceramic capacitors as close as possible to the IC pins to minimize parasitic inductance. Use X5R or X7R dielectric for stability across temperature; avoid Y5V which loses capacitance rapidly with voltage and temperature. The GND pin should be tied to a low-impedance ground plane for best PSRR and thermal performance.
Do not use output capacitors with ESR > 200 mohm - this can cause instability and oscillation on the output. Tie the ON/OFF pin to VIN with a 100 kohm pull-up if shutdown control is not needed (the input is high-impedance and may float). For legacy silicon, verify the maximum VIN rating before connecting to a 12V or 15V rail.
Thông tin tuân thủ
RoHS and REACH status derived from the TI LP2981 product page and the NOPB suffix designation. LP2981 family is industrial-grade, not AEC-Q100 automotive qualified; for automotive applications consider TPS7A02 or TPS7A4501.
