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Texas Instruments LP3905SD-A3/NOPB
- Part No.:
- LP3905SD-A3/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Power Management - Specialized
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LP3905SD-A3/NOPB.pdf
- Description:
- IC REG LDO DUAL 600MA BUCK 14SON
- Quantity:
- Payment:
- Shipping:
Inventory:3,216
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Product details
Overview
LP3905SD-A3/NOPB from Texas Instruments is a dual-buck + dual-LDO power management unit (PMU) for low-power handheld systems. It integrates two 600mA synchronous buck regulators (2MHz fixed PWM, PFM-PWM auto-switching), two 150mA LDOs (±3% accuracy, 13.5µVrms noise), and independent enable control (EN1 for Buck1/LDOs, EN2 for Buck2). It powers baseband processors and I/O rails in battery-powered mobile devices.
For engineers reviewing the LP3905SD-A3/NOPB datasheet, LP3905SD-A3/NOPB pinout, LP3905SD-A3/NOPB application, or LP3905SD-A3/NOPB equivalent, key selection considerations include its 14-pin WSON package, dual-enable sequencing, ±4% buck output accuracy, thermal shutdown protection, and compatibility with 2.2µH inductors and 10µF ceramic output capacitors.
Technical Context
The LP3905SD-A3/NOPB implements voltage-mode PWM control with input voltage feed-forward for stable line regulation, and automatically transitions to PFM mode below ~50–115mA (depending on VIN) to minimize quiescent current. Its internal 0.5V feedback reference enables precise output voltage setting via external resistor dividers on FB1/FB2 pins.
Buck regulation uses internal PFET/NFET synchronous rectification (RDSON_P = 500mΩ typ, RDSON_N = 400mΩ typ) with peak current limiting (1000mA typ) and soft-start (stepwise current limit ramp). LDOs feature 80mV dropout at 100mA, 70dB PSRR at 1kHz, and active pulldown when disabled.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Buck Output Current | 600mA per channel - supports high-current processor cores or peripherals without external boost stages |
| LDO Output Current | 150mA per channel - sufficient for I/O banks, audio codecs, or FPGA configuration logic |
| Switching Frequency | 2MHz (typ) - enables use of compact 2.2µH inductors and reduces EMI in space-constrained handheld PCBs |
| Buck Efficiency | 90% at 300mA - extends battery life in Li-ion-powered portable devices |
| LDO Noise | 13.5µVrms - meets low-noise analog supply requirements for ADCs or RF front-ends |
| Output Accuracy | ±4% (buck), ±3% (LDO) - ensures reliable operation across temperature and load without external trimming |
| Package | 14-pin WSON (4mm × 4mm × 0.8mm) - surface-mount footprint compatible with automated assembly and thermal vias under DAP |
Pinout & Package
LP3905SD-A3/NOPB is housed in a thermally enhanced 14-pin WSON package (TI package code NHL0014B) with an exposed die attach pad (SGND) for improved heat dissipation. The package measures 4.0mm × 4.0mm × 0.8mm and requires solder reflow per JEDEC J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN1 | Enable Input | Active-high control for Buck1, LDO1, and LDO2 - initiates coordinated power-up sequence |
| EN2 | Enable Input | Independent active-high control for Buck2 - allows staggered startup to limit inrush current |
| FB1 / FB2 | Feedback Input | 0.5V reference point for adjustable buck outputs - sets VOUT via external resistor divider |
| SW1 / SW2 | Switch Node | Drives external inductor - connects to internal PFET drain and NFET source in synchronous topology |
| VIN1 | Power Input | Main supply for both buck regulators - must be ≥3V and tied to VIN2 during power-up |
| VIN2 | Power Input | Supply for both LDOs - requires same rail as VIN1 for proper sequencing and UVLO release |
| LDO1 / LDO2 | Regulated Output | Low-noise, low-dropout outputs - each delivers up to 150mA with 80mV dropout at full load |
| GND / TGND / GND_B1 / GND_B2 / SGND | Ground Terminals | Dedicated ground returns isolate LDO, buck, thermal, and substrate paths - critical for noise separation and thermal performance |
Key Features
| Feature | Design Value |
|---|---|
| Auto-switching PFM-PWM mode | Reduces IQ to 16µA (typ) in light-load sleep mode while maintaining <±1.7% output voltage deviation |
| Integrated soft-start | Prevents inrush current spikes via stepwise current limit ramp (70mA → 140mA → 280mA → 1000mA) |
| Thermal & current overload protection | Shuts down at 160°C junction temp with 20°C hysteresis; limits peak switch current to 1220mA max |
| UVLO with 2.7V–3.1V threshold | Blocks operation until input stabilizes above battery brownout level - prevents erratic startup |
| PSRR of 70dB @ 1kHz | Rejects ripple from noisy buck supplies feeding sensitive analog circuitry powered by LDOs |
| Separate enable pins | EN1/EN2 allow independent control of power domains - essential for dynamic power gating in multi-core SoCs |
Applications
| Baseband Processor Power | Peripheral I/O Supply |
|---|---|
Use Scenario: Powers ARM9/ARM11 baseband processors in 2G/3G smartphones with dynamic voltage scaling. IC Role / Device Role / Timing Role: Dual-buck regulator delivers core (1.2V) and memory (1.8V) rails; LDOs supply PLL and analog blocks. Use Value: 90% efficiency at 300mA extends talk time; PFM mode preserves standby battery life. |
Use Scenario: Supplies voltage to camera interface, USB PHY, and SD card controller in portable media players. IC Role / Device Role / Timing Role: LDO1/LDO2 provide clean 2.8V/3.3V I/O rails; buck regulators power high-speed digital logic. Use Value: 13.5µVrms LDO noise prevents image sensor artifacts; ±3% accuracy ensures signal integrity across temperature. |
| FPGA Configuration & Core Logic | Audio Codec Biasing |
Use Scenario: Delivers multiple rails for Spartan-6 or Cyclone III FPGA in handheld test equipment. IC Role / Device Role / Timing Role: Buck1 (1.2V) powers core logic; Buck2 (2.5V) feeds I/O bank; LDOs (3.3V/1.8V) supply configuration and auxiliary circuits. Use Value: Independent EN1/EN2 sequencing matches FPGA power-up order; thermal shutdown protects against overtemperature during bitstream loading. |
Use Scenario: Provides low-noise bias for stereo audio DAC/ADC in Bluetooth headsets. IC Role / Device Role / Timing Role: LDO2 supplies 1.8V analog core; LDO1 provides 3.3V digital interface; bucks power Class-D amplifier stage. Use Value: 70dB PSRR at 1kHz suppresses switching noise coupling into audio path; 80mV dropout enables operation near battery end-of-life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multi-rail PMU applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65023RSBR | Three buck + two LDO; 3MHz switching; I2C programmable outputs; larger 48-pin QFN | Supports higher integration and dynamic voltage control - suited for application processors requiring runtime rail adjustment | Choose TPS65023RSBR when I2C configurability and >2 buck channels are required; not pin-compatible |
| MAX8646ETE+ | Dual buck + triple LDO; 3MHz switching; integrated battery charger; 24-pin TQFN | Includes linear charger and additional LDO - targets single-battery systems needing charge management | Choose MAX8646ETE+ when battery charging functionality is mandatory; different enable logic and pinout |
Compared with LP3905SD-A3/NOPB, TPS65023RSBR offers greater flexibility via I2C but requires PCB redesign and firmware support, while MAX8646ETE+ adds charging capability at the cost of higher BOM count and thermal complexity - LP3905SD-A3/NOPB remains optimal for cost-sensitive, fixed-voltage handheld PMU designs.
Availability
LP3905SD-A3/NOPB is available at Aetrix Electronics and suitable for smartphone baseband power, portable media player I/O supply, and FPGA embedded system design requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.
Supply support for LP3905SD-A3/NOPB 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 technologies, with decades of experience in battery-operated portable electronics.
The LP3905SD-A3/NOPB belongs to TI's low-power PMU product line, engineered specifically for energy-constrained handheld applications such as feature phones, PDAs, and portable medical devices where small size, high efficiency, and robust thermal behavior are critical.
FAQ
What is the function of the SGND pad on the LP3905SD-A3/NOPB package?
The SGND pad on the LP3905SD-A3/NOPB is the exposed die attach pad, electrically connected to substrate ground and thermally coupled to the silicon die. It must be soldered to a dedicated PCB copper pour with thermal vias to achieve the specified θJA of 37.3°C/W. Leaving SGND unconnected degrades thermal performance and risks thermal shutdown under sustained 600mA buck loads.
Does the LP3905SD-A3/NOPB support adjustable output voltages for its buck regulators?
Yes, the LP3905SD-A3/NOPB supports adjustable buck outputs via external resistor dividers on FB1 and FB2 pins. Each feedback network sets VOUT using VFB = 0.5V as reference, enabling outputs from 1.0V to 3.3V. The LP3905SD-A3/NOPB datasheet provides recommended R1FB/R2FB values and optional C1 compensation capacitors for stability across all target voltages.
How does the LP3905SD-A3/NOPB handle power sequencing between VIN1 and VIN2?
The LP3905SD-A3/NOPB requires VIN1 and VIN2 to be tied together at all times for proper power-up. If separated, UVLO may prevent activation or cause unstable regulation. The device monitors combined input via internal UVLO (2.7V–3.1V threshold) and only enables regulation after both rails exceed this level - ensuring synchronized startup of buck and LDO sections.
What is the maximum allowable output capacitance for the LDOs in the LP3905SD-A3/NOPB?
The LP3905SD-A3/NOPB LDOs are stable with output capacitances from 0.47µF (for ≤100mA loads) up to 1.0µF (for full 150mA loads), using X7R/X5R ceramic types. Exceeding 1.0µF is not characterized and may cause instability or degraded transient response. The datasheet specifies 1.0µF as the maximum verified value for guaranteed performance across temperature and process variation.
Can the LP3905SD-A3/NOPB operate with a 2.8V input supply?
No - the LP3905SD-A3/NOPB has a minimum operating input voltage of 3.0V per its Absolute Maximum Ratings and Operating Ratings tables. At 2.8V, the internal UVLO remains active, preventing regulation. The device will not power up or deliver regulated outputs until VIN1/VIN2 rise above 2.7V (UVLO release threshold) and stabilize at ≥3.0V for functional operation.
LP3905SD-A3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Handheld/Mobile Devices
- Current - Supply:
- -
- Voltage - Supply:
- 3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-WSON (4x4)
LP3905SD-A3/NOPB FAQ
1.How can I place an order for LP3905SD-A3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LP3905SD-A3/NOPB 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 LP3905SD-A3/NOPB reliable?
The price and inventory of LP3905SD-A3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP3905SD-A3/NOPB is usually 5 days.
3.What payment methods are accepted for LP3905SD-A3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP3905SD-A3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP3905SD-A3/NOPB?
LP3905SD-A3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP3905SD-A3/NOPB 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 LP3905SD-A3/NOPB?
For technical support, including LP3905SD-A3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP3905SD-A3/NOPB requirements.
6.How does Aetrix verify that LP3905SD-A3/NOPB is sourced from the original manufacturer or authorized distributors?
All LP3905SD-A3/NOPB 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 LP3905SD-A3/NOPB meets industry standards.
7.What is the process for return or replacement of LP3905SD-A3/NOPB?
All LP3905SD-A3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LP3905SD-A3/NOPB, 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 LP3905SD-A3/NOPB part is unused and in its original packaging.
Return procedure for LP3905SD-A3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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