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Texas Instruments LM3351MMX/NOPB
- Part No.:
- LM3351MMX/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM3351MMX/NOPB.pdf
- Description:
- IC REG CHRG PUMP INV 50MA 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,321
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Product details
Overview
LM3351MMX/NOPB from Texas Instruments (formerly National Semiconductor) is a CMOS switched-capacitor voltage converter IC providing bidirectional 3.3V ↔ 5V DC-DC conversion without inductors. It delivers 5V output from 3.3V input (3/2 step-up) or 3.3V output from 5V input (2/3 step-down), achieves 95% typical efficiency at 50 mA, features 200 kHz switching frequency, and operates across −40°C to +85°C for portable mixed-voltage systems.
For engineers reviewing the LM3351MMX/NOPB datasheet, LM3351MMX/NOPB pinout, LM3351MMX/NOPB application, or LM3351MMX/NOPB equivalent, key selection criteria include its fixed-ratio charge-pump architecture, Mini SO-8 package compatibility, ultra-low 250 nA shutdown current, absence of magnetic components, and dual-mode operation requiring only four 1 µF ceramic capacitors.
Technical Context
The LM3351MMX/NOPB implements a fixed-ratio charge-pump topology using internal CMOS switches clocked by a 1.6 MHz oscillator (divided to 200 kHz output switching). Its architecture supports two distinct configurations: step-up mode (Vlow = input, Vhigh = output) and step-down mode (Vhigh = input, Vlow = output), with no mode-select pin - configuration is determined solely by external connections.
It requires an external Schottky diode in step-up mode to bias Vhigh during startup but operates diode-free in step-down mode. The device lacks short-circuit protection and relies on external capacitor selection (C1, C2, Cin, Cout) - all specified as 1.0 µF ±20% X7R ceramics - to define ripple, transient response, and stability across temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Conversion Ratio | Fixed 3/2 (step-up) or 2/3 (step-down); enables precise 3.3V/5V interconversion without regulation loop |
| Switching Frequency | 200 kHz (typical); allows use of small, low-cost 1 µF ceramic capacitors instead of bulky inductors |
| Output Impedance | 4.2 Ω (step-up), 1.8 Ω (step-down); defines load regulation and voltage droop under 50 mA load |
| Power Efficiency | 95% (typical at 50 mA); minimizes thermal rise and extends battery life in portable applications |
| Shutdown Current | 250 nA (typical); enables ultra-low-power state for system-level power gating |
| Operating Temperature | −40°C to +85°C; supports industrial-grade deployment in handheld and embedded environments |
| Input Voltage Range | 2.5–3.65 V (step-up), 2.2–5.5 V (step-down); accommodates battery voltage sag and supply tolerance |
Pinout & Package
LM3351MMX/NOPB is housed in an 8-pin Mini SOIC (SO-8) package (NSC drawing MUA08A, marking S05A), measuring 4.9 mm × 3.9 mm × 1.75 mm, with standard gull-wing lead form for surface-mount assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Cap1+ | Charge pump capacitor positive terminal | Connects to + side of first flying capacitor; critical path for energy transfer timing |
| 2 - Cap1− | Charge pump capacitor negative terminal | Completes first flying capacitor loop; must be routed with minimal trace inductance |
| 3 - Cap2+ | Charge pump capacitor positive terminal | Connects to + side of second flying capacitor; phase-shifted relative to Cap1 for continuous pumping |
| 4 - Cap2− | Charge pump capacitor negative terminal | Completes second flying capacitor loop; shares ground reference with Cap1− for balanced switching |
| 5 - Vlow | Low-voltage terminal | Input in step-up mode; output in step-down mode - determines functional direction via external wiring |
| 6 - Gnd | Power and signal reference | Common return for all capacitors and enable logic; requires low-impedance plane connection |
| 7 - Vhigh | High-voltage terminal | Output in step-up mode; input in step-down mode - polarity and role defined by circuit configuration |
| 8 - Enable | CMOS logic control input | Active-high enable (1.7 V threshold); ties to Vlow or Vhigh rail for mode-synchronized activation |
Key Features
| Feature | Design Value |
|---|---|
| No-inductor DC-DC conversion | Eliminates EMI, size, and cost penalties of magnetic components while enabling PCB area reduction |
| Dual-direction fixed-ratio operation | Supports both 3.3V→5V and 5V→3.3V conversion with identical IC - no BOM variants needed |
| 250 nA shutdown current | Enables microamp-level system sleep states without external disconnect circuitry |
| 200 kHz switching frequency | Permits full use of inexpensive, high-SRF 1 µF X7R ceramics - no special capacitor sourcing required |
| Mini SO-8 footprint | Provides drop-in compatibility with LM3350MM and other legacy Mini SO-8 charge pumps |
Applications
| Laptop Power Management | PCMCIA Card Interface |
|---|---|
Use Scenario: Generating 5V peripheral bus power from a 3.3V main system rail in ultra-thin notebooks. IC Role / Device Role / Timing Role: Step-up voltage converter supplying regulated 5V to USB-compatible peripherals and card slots. Use Value: Replaces inductor-based boost converters to reduce height, EMI, and component count in space-constrained chassis. |
Use Scenario: Providing isolated 3.3V I/O supply from 5V host controller in hot-pluggable PCMCIA memory cards. IC Role / Device Role / Timing Role: Step-down voltage converter delivering clean, low-noise 3.3V logic power synchronized to card insertion detection. Use Value: Enables single-rail 5V host design while meeting JEIDA/PCMCIA 3.3V interface compliance without magnetics. |
| Handheld Instrumentation | Mixed-Voltage Embedded Controller |
Use Scenario: Powering 5V analog front-end sensors and ADCs from a 3.3V Li-ion battery-powered microcontroller subsystem. IC Role / Device Role / Timing Role: Bidirectional charge-pump converter dynamically reconfigured via firmware-controlled enable routing. Use Value: Delivers stable 5V sensor bias with <4.2 Ω source impedance, ensuring <300 mV droop at full 50 mA load. |
Use Scenario: Level-shifting between 3.3V FPGA I/O banks and 5V legacy communication peripherals (e.g., RS-232 transceivers). IC Role / Device Role / Timing Role: Fixed-ratio DC-DC converter acting as dedicated voltage translator with independent enable control per rail. Use Value: Provides galvanically isolated, low-ripple 3.3V/5V rails without shared ground noise coupling typical of LDO solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor voltage converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3350MMX/NOPB | Same Mini SO-8 package and pinout; 3× higher quiescent current (750 µA vs. 1.1 mA active, 750 µA vs. 250 nA shutdown) | Less suitable for battery-critical designs due to higher standby drain; identical layout compatibility | Select LM3351MMX/NOPB when >99% battery runtime extension in sleep mode is required |
| MAX680ESA+ | Pin-compatible SO-8; 2.5V–6.5V input range; 90% efficiency at 20 mA; no step-down mode | Single-direction (only ±2× inversion); requires different capacitor values (10 µF); lacks 2/3 ratio | Choose MAX680ESA+ only for pure inverting applications where 3.3V→5V upconversion suffices |
Compared with LM3350MMX/NOPB and MAX680ESA+, the LM3351MMX/NOPB uniquely combines bidirectional 3.3V/5V conversion, ultra-low shutdown current, and identical Mini SO-8 footprint - making it the sole option for space-constrained, battery-sensitive systems requiring reversible rail translation without layout redesign.
Availability
LM3351MMX/NOPB is available at Aetrix Electronics and suitable for laptop computers, PCMCIA cards, and handheld instrumentation requiring stable component supply with long-term industrial availability.
Supply support for LM3351MMX/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 acquired National Semiconductor in 2011 and maintains its precision analog and power management portfolio, emphasizing high-reliability, low-power, and integrated solutions for industrial and portable markets.
The LM3351MMX/NOPB belongs to TI's legacy switched-capacitor DC-DC converter family, designed specifically to replace inductor-based regulators in compact, EMI-sensitive, battery-powered applications where fixed-ratio voltage translation is sufficient.
FAQ
What is the primary function of the LM3351MMX/NOPB?
The LM3351MMX/NOPB is a fixed-ratio switched-capacitor voltage converter that provides bidirectional 3.3V ↔ 5V DC-DC conversion. It operates as a step-up converter (3.3V input → 5V output) or step-down converter (5V input → 3.3V output) depending on external wiring, using only four ceramic capacitors and no inductor. Its core purpose is efficient, low-EMI rail translation in space-constrained portable systems.
Does the LM3351MMX/NOPB require an external diode?
Yes - the LM3351MMX/NOPB requires an external Schottky diode in step-up mode to supply initial bias to the Vhigh pin during startup. This diode is not needed in step-down mode. The LM3351MMX/NOPB datasheet explicitly specifies D1 in Figure 1 (Step-Up Converter) and confirms its omission in Figure 2 (Step-Down Converter), making diode usage mode-dependent and non-optional for reliable step-up operation.
What is the shutdown current specification for the LM3351MMX/NOPB?
The LM3351MMX/NOPB has a typical shutdown current of 250 nA when the ENABLE pin is driven low (0 V). This value is confirmed in the Electrical Characteristics table under "IQ1 Quiescent Current - Shutdown Mode" for both step-up and step-down configurations, and is critical for ultra-low-power system sleep states in battery-operated devices.
Can the LM3351MMX/NOPB operate outside the 3.3V/5V conversion range?
No - the LM3351MMX/NOPB is strictly a fixed-ratio converter with only two operational modes: 3/2 step-up (nominally 3.3V → 5V) and 2/3 step-down (nominally 5V → 3.3V). Its architecture does not support adjustable output voltages or other ratios. Input ranges are limited to 2.5–3.65 V (step-up) and 2.2–5.5 V (step-down), and deviation from nominal voltages reduces output accuracy and efficiency.
Is the LM3351MMX/NOPB pin-compatible with other National Semiconductor charge pumps?
Yes - the LM3351MMX/NOPB is explicitly documented as pin-for-pin compatible with the LM3350MM series in the General Description section of its datasheet. Both share identical Mini SO-8 packaging (MUA08A), identical pin functions (Cap1+, Cap1−, Cap2+, Cap2−, Vlow, Gnd, Vhigh, Enable), and identical board footprint, enabling direct replacement with improved quiescent current performance.
LM3351MMX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Ratiometric
- Output Configuration:
- Positive
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 3/2Vin, 2/3Vin
- Voltage - Output (Max):
- -
- Current - Output:
- 50mA
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
LM3351MMX/NOPB FAQ
1.How can I place an order for LM3351MMX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3351MMX/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 LM3351MMX/NOPB reliable?
The price and inventory of LM3351MMX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3351MMX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3351MMX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3351MMX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3351MMX/NOPB?
LM3351MMX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3351MMX/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 LM3351MMX/NOPB?
For technical support, including LM3351MMX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3351MMX/NOPB requirements.
6.How does Aetrix verify that LM3351MMX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3351MMX/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 LM3351MMX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3351MMX/NOPB?
All LM3351MMX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3351MMX/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 LM3351MMX/NOPB part is unused and in its original packaging.
Return procedure for LM3351MMX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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