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Texas Instruments LM2771SD
- Part No.:
- LM2771SD
- Manufacturer:
- Texas Instruments
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LM2771SD.pdf
- Description:
- IC REG CHARGE PUMP 1.5V 10WSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,825
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Product details
Overview
LM2771SD from Texas Instruments is a fixed-output, switched-capacitor step-down DC/DC converter delivering 1.5V at up to 250mA without inductors. It operates from 2.7V–5.5V input, achieves 81% efficiency at 200mA from 3.6V input, and delivers ultra-low 8mV output ripple in fixed-frequency mode. It serves as a compact, low-noise power supply for DSP cores and memory rails in portable electronics.
For engineers reviewing the LM2771SD datasheet, LM2771SD pinout, LM2771SD application, or LM2771SD equivalent, key selection criteria include its WSON-10 package footprint, 1.1MHz switching frequency, 1.7% output voltage accuracy, shutdown disconnect functionality, and compatibility with standard 1µF/4.7µF ceramic capacitor networks.
Technical Context
The LM2771SD implements a regulated 0.5× charge pump topology with pre-regulated 1.1MHz fixed-frequency operation during moderate-to-heavy loads, switching automatically to low-ripple PFM mode below ~30mA. Its internal MOS switch control limits gate drive to suppress ripple while maintaining regulation.
At VIN < 3.5V (typ.), it enters pass mode-drawing input current equal to load current-with LDO-like efficiency; above that threshold, it engages buck-mode charge transfer with half-current draw. Thermal shutdown activates at 150°C (typ.) and releases at 140°C (typ.), and current limiting caps output at 500mA (typ.).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.5V ±1.7% over 0–200mA load; ±3.7% over full 0–250mA range |
| Max Output Current | 250mA continuous; internal 500mA current limit protects against short-circuit faults |
| Input Voltage Range | 2.7V to 5.5V; supports single-cell Li-ion (3.6V nominal) and USB-powered systems |
| Switching Frequency | 1.1MHz typ. (0.8–1.4MHz range); enables small external capacitors and low EMI filtering |
| Output Ripple | 8mV peak-to-peak @ 250mA in fixed-frequency mode; 12mV in PFM mode @ <40mA |
| Efficiency | 81% @ 200mA, VIN = 3.6V; exceeds typical LDO efficiency by ~2× in buck mode |
| Quiescent Current | 50µA typ. in active mode; 0.5µA max in shutdown with EN = LOW |
Pinout & Package
LM2771SD is housed in a 3mm × 3mm × 0.8mm WSON-10 (DSC0010A) package with exposed thermal pad tied to GND. The package supports lead-free reflow (MSL Level-1, 260°C peak) and features 10 terminals including two dedicated ground pins and three no-connect (NC) pins.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power Input | Accepts 2.7–5.5V; requires local 1µF ceramic decoupling; connects to flying capacitor during charge phase |
| GND (Pins 2 & 9) | Ground Reference | Dual GND pins reduce impedance; die-attach pad is internally connected to GND for thermal conduction |
| VOUT | Regulated Output | Delivers fixed 1.5V; connects to 4.7µF output capacitor; disconnected from VIN during shutdown |
| C1+ | Flying Cap Anode | Positive terminal of external 1µF flying capacitor; switches between VIN and VOUT nodes |
| C1− | Flying Cap Cathode | Negative terminal of external 1µF flying capacitor; referenced to GND during charge/discharge cycles |
| EN | Enable Control | Logic-high (>0.95×VIN) enables regulator; internal 350kΩ pull-down ensures default OFF state |
| NC (Pins 4, 5, 8) | No Connect | Unbonded pads; must remain unconnected per TI design; no routing or thermal tie required |
Key Features
| Feature | Design Value |
|---|---|
| No-inductor architecture | Enables ultra-compact 3mm × 3mm layout using only three MLCCs-eliminates EMI-prone magnetics and simplifies PCB routing |
| Auto PFM/Fixed-Frequency mode | Maintains high efficiency across full 0–250mA load range: fixed 1.1MHz for low noise, PFM for <30mA to minimize quiescent loss |
| Shutdown disconnect | Completely isolates VOUT from VIN when EN = LOW, preventing backfeed and enabling true system-level power gating |
| Pass-mode operation | Below 3.5V input, operates as linear pass device-preserving regulation while avoiding switching losses and ripple |
| Thermal + current protection | Integrated thermal shutdown (150°C trip) and 500mA current limit prevent damage under overload or poor heatsinking conditions |
Applications
| Mobile Baseband Processor Power | DSP Core Supply |
|---|---|
Use Scenario: Powers ARM-based baseband processors in 3G/4G handsets requiring stable 1.5V at up to 200mA during burst transmission. IC Role / Device Role / Timing Role: Primary step-down regulator replacing discrete LDOs; provides clean, low-ripple rail independent of battery voltage sag. Use Value: 81% efficiency extends talk time vs. LDO; 8mV ripple avoids clock jitter in RF synthesizers and ADC references. | Use Scenario: Supplies voltage to programmable DSP cores in portable audio players and voice recorders. IC Role / Device Role / Timing Role: Dedicated low-noise power source for digital signal processing blocks; enabled only during active decode cycles. Use Value: Auto PFM mode draws just 50µA quiescent current during idle, minimizing standby drain; soft-start prevents inrush into large DSP decoupling banks. |
| Low-Power Memory Interface | Portable Medical Sensor Node |
Use Scenario: Generates 1.5V for LPDDR2/LPDDR3 I/O rails in handheld diagnostic devices with tight space constraints. IC Role / Device Role / Timing Role: Point-of-load regulator placed adjacent to memory package; synchronized via EN to match memory active/idle states. Use Value: WSON-10 footprint fits within memory ball grid; 1.7% output accuracy ensures reliable interface timing margins across temperature. | Use Scenario: Powers analog front-end and microcontroller in battery-operated wearable ECG monitors. IC Role / Device Role / Timing Role: Single-chip solution for mixed-signal subsystem; supplies both digital logic and precision analog reference circuits. Use Value: Pass-mode operation at 3.2V battery voltage delivers LDO-equivalent noise with no switching artifacts; shutdown current <0.5µA preserves multi-week shelf life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX8814EUB+T | Fixed 1.5V output, 250mA, 1.2MHz switching, WLP-12 package (2.1mm × 1.6mm) | Smaller footprint but higher 12mV ripple; lacks pass-mode transition behavior | Preferred where board area is critical and ripple tolerance >12mV; not drop-in due to different pinout and package |
| TPS60403DBVR | Adjustable output (1.5–5V), 60mA max, 1MHz, SOT-23-5 package | Lower current capability; requires external feedback resistors; no PFM mode or pass-mode fallback | Suitable for low-power sensor biasing where adjustable voltage is needed; insufficient for 250mA loads |
Compared with MAX8814EUB+T and TPS60403DBVR, the LM2771SD uniquely combines 250mA capability, ultra-low 8mV ripple, automatic PFM/fixed-frequency mode switching, and seamless pass-mode transition below 3.5V-making it optimal for Li-ion-powered portable systems demanding both efficiency and noise performance.
Availability
LM2771SD is available at Aetrix Electronics and suitable for mobile phone power management, DSP core supplies, and portable medical sensor nodes requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.
Supply support for LM2771SD includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-efficiency DC/DC conversion.
The LM2771SD belongs to TI's switched-capacitor DC/DC converter product line, engineered specifically for space-constrained, battery-powered applications needing clean, inductorless voltage reduction from 2.7–5.5V inputs to fixed 1.5V outputs.
FAQ
What is the recommended capacitor configuration for LM2771SD in high-current applications?
For high-current applications up to 250mA, TI specifies 1µF input (CIN), 1µF flying (C1), and 4.7µF output (COUT) ceramic capacitors-preferably X5R/X7R MLCCs with ≤15mΩ ESR. This configuration yields 8mV output ripple and stable regulation. TDK C1005X5R1A105K and C1608X5R0J475K are validated equivalents. Larger COUT values further reduce ripple but increase solution size and cost.
Does LM2771SD require external compensation components?
No, LM2771SD is fully integrated and requires no external compensation. Its internal regulation loop is factory-trimmed for stability with the specified 1µF/4.7µF capacitor network. Adding external RC networks or altering capacitor values outside TI's validated configurations may cause instability, excessive ripple, or failure to regulate-especially under dynamic load steps.
How does LM2771SD behave when input voltage drops below 3.5V?
When VIN falls below ~3.5V, LM2771SD automatically transitions from switched-capacitor buck mode to linear pass mode-drawing input current equal to load current instead of half. This preserves regulation and eliminates switching noise while maintaining 1.5V output. Efficiency becomes comparable to an LDO, and output ripple drops further, making it ideal for end-of-battery-life operation in Li-ion systems.
Can LM2771SD be used with tantalum or electrolytic capacitors?
No-tantalum and aluminum electrolytic capacitors are explicitly discouraged for LM2771SD. Their high ESR (often >100mΩ) increases output/input ripple and risks thermal runaway in the flying capacitor path. Polarized types also risk reverse bias during charge-pump switching. Only low-ESR ceramic capacitors (X5R/X7R MLCCs) meet TI's specifications for reliability and performance.
What thermal considerations apply to LM2771SD in continuous 250mA operation?
At 250mA and VIN = 5.5V, LM2771SD dissipates ~0.7W. With θJA = 55°C/W, junction temperature rise is ~39°C above ambient-well within the −30°C to +110°C operating range. However, PCB layout is critical: the exposed thermal pad must be soldered to a ≥100mm² copper pour with ≥4 thermal vias to inner ground planes. Without this, thermal shutdown may trigger at TA > 70°C.
LM2771SD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.5V
- Voltage - Output (Max):
- -
- Current - Output:
- 250mA
- Frequency - Switching:
- 1.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-WSON (3x3)
LM2771SD FAQ
1.How can I place an order for LM2771SD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2771SD on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM2771SD reliable?
The price and inventory of LM2771SD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2771SD is usually 5 days.
3.What payment methods are accepted for LM2771SD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2771SD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2771SD?
LM2771SD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2771SD order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM2771SD?
For technical support, including LM2771SD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2771SD requirements.
6.How does Aetrix verify that LM2771SD is sourced from the original manufacturer or authorized distributors?
All LM2771SD products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM2771SD meets industry standards.
7.What is the process for return or replacement of LM2771SD?
All LM2771SD units undergo pre-shipment inspection (PSI). If there is an issue with LM2771SD, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM2771SD part is unused and in its original packaging.
Return procedure for LM2771SD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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