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Texas Instruments LM7705MM/NOPB
- Part No.:
- LM7705MM/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM7705MM/NOPB.pdf
- Description:
- IC REG CHARGE PUMP -0.23V 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,001
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Product details
Overview
LM7705MM/NOPB from Texas Instruments is a low-noise switched-capacitor negative bias generator delivering a regulated −0.232 V output with ±5% tolerance, 4 mVPP ripple, and up to 98% conversion efficiency across 3 V–5.25 V input. It enables true-zero output operation in single-supply rail-to-rail amplifiers for precision sensor signal conditioning and ADC interfacing.
For engineers reviewing the LM7705MM/NOPB datasheet, LM7705MM/NOPB pinout, LM7705MM/NOPB application, or LM7705MM/NOPB equivalent, key selection criteria include fixed −0.232 V regulation accuracy, shutdown current of 20 nA, 78 µA quiescent current, 500 µs turnon time, and compatibility with standard 8-pin VSSOP PCB layouts for low-voltage split-power supply designs.
Technical Context
The LM7705MM/NOPB integrates a pre-regulator, charge-pump inverter, and post-regulator to generate a stable negative bias voltage from a single positive supply. Its dual-phase oscillator (91–92 kHz) drives external CFLY and CRES capacitors to invert and regulate voltage without inductors.
It operates in two functional modes: active (SD = LOW) delivers −0.232 V at up to 20 mA sink current with 0.14%/mA load regulation; shutdown (SD = HIGH) disables output and reduces supply current to 20 nA while grounding VOUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −0.232 V ±5% - precisely sets amplifier negative rail to enable true-zero output swing without exceeding 5.5 V total supply differential. |
| Output Ripple | 4 mVPP at −20 mA - low noise ensures minimal interference in precision analog front-ends driving 12-bit+ ADCs. |
| Supply Range | 3 V to 5.25 V - supports common logic rails (3.3 V, 5 V) without external LDOs or level-shifting. |
| Quiescent Current | 78 µA at 3.3 V - enables battery-powered portable instrumentation with multi-year standby life. |
| Shutdown Current | 20 nA - reduces system power during sleep modes without requiring additional power-gating circuitry. |
| Turnon Time | 500 µs at 3.3 V - fast activation allows dynamic bias enabling synchronized with signal acquisition windows. |
| Efficiency | 98% at −5 mA - minimizes heat generation and input supply loading in space-constrained embedded systems. |
Pinout & Package
LM7705MM/NOPB uses an 8-pin VSSOP package (3.00 mm × 3.00 mm body size) with exposed thermal pad for enhanced thermal performance in compact layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CF+ | CFLY capacitor positive terminal | Connects to flying capacitor anode; critical path for charge transfer timing and ripple control. |
| VSS | Power ground | Dual ground pins (2 & 5) reduce ground impedance and improve PSRR in noise-sensitive applications. |
| SD | Shutdown control input | Active-low logic interface; pulls VOUT to GND when HIGH, enabling ultra-low-power sleep states. |
| VDD | Positive supply input | Accepts 3 V–5.25 V; internal pre-regulator maintains stable operation across input variation. |
| VOUT | Negative regulated output | Delivers −0.232 V to amplifier negative supply pin; designed for direct connection to op-amp V– terminals. |
| CRES | Reserve capacitor connection | Stabilizes post-regulated output; value (22 µF typical) directly impacts load transient response and ripple. |
| CF− | CFLY capacitor negative terminal | Completes charge-pump switching loop; paired with CF+ to form inversion stage. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed −0.232 V regulation | Eliminates need for external feedback resistors or trimming, ensuring consistent zero-reference across production batches. |
| Low 4 mVPP output ripple | Preserves signal integrity in high-resolution data acquisition paths where noise floor directly limits effective resolution. |
| 98% conversion efficiency | Reduces thermal stress on adjacent components and extends battery life in portable instrumentation without heatsinking. |
| 20 nA shutdown current | Enables micro-power system architectures where bias generation must be disabled between measurement cycles. |
| −40°C to 125°C operation | Supports industrial and automotive environments where amplifier bias stability must be maintained across extreme temperature gradients. |
Applications
| True-Zero Amplifier Outputs | Portable Instrumentation |
|---|---|
Use Scenario: Single-supply rail-to-rail op amp (e.g., LMP7701) driving 12-bit ADC with 0–90 mV sensor output. IC Role / Device Role / Timing Role: Provides −0.232 V negative rail to eliminate output saturation at 0 V, enabling full ADC code utilization. Use Value: Recovers 40+ lost ADC quantization levels versus single-supply-only operation, improving effective resolution by ≥0.6 bits. | Use Scenario: Handheld gas analyzer using low-power op amps and 16-bit SAR ADC for ppm-level detection. IC Role / Device Role / Timing Role: Generates stable negative bias during active measurement; enters 20 nA shutdown between readings. Use Value: Extends battery life by >3× versus continuous-bias solutions while maintaining sub-mV offset accuracy. |
| Low-Voltage Split-Power Supplies | Medical Sensor Interfaces |
Use Scenario: Wearable ECG front-end requiring ±2.5 V rails from single 3.3 V Li-ion cell. IC Role / Device Role / Timing Role: Generates −0.232 V rail to extend op amp output swing below ground without violating 5.5 V max differential rating. Use Value: Avoids costly dual-supply redesign; maintains amplifier functionality within existing IC voltage ratings. | Use Scenario: Disposable glucose monitor with single-supply transimpedance amplifier and low-noise ADC. IC Role / Device Role / Timing Role: Supplies clean −0.232 V bias to TIA's negative input, reducing input-referred offset drift over temperature. Use Value: Improves calibration stability across −40°C to 85°C operating range, reducing recalibration frequency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative bias generator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1682ASA+ | −0.25 V output, higher 10 mVPP ripple, 120 µA quiescent current, no shutdown pin | Lacks active shutdown; less suitable for duty-cycled portable systems requiring ultra-low standby power | Select MAX1682ASA+ only if shutdown functionality is unnecessary and higher ripple is acceptable. |
| TPS60403DBVR | Adjustable −1.5 V to −5 V output via resistor divider, 15 mVPP ripple, 110 µA quiescent current | Requires external resistors and compensation; not drop-in compatible due to different pinout and regulation architecture | Choose TPS60403DBVR only when variable negative voltage is required and board layout can accommodate redesign. |
Compared with MAX1682ASA+ and TPS60403DBVR, LM7705MM/NOPB offers the lowest output ripple (4 mVPP) and lowest shutdown current (20 nA), making it optimal for precision, battery-sensitive true-zero amplifier applications where fixed −0.232 V regulation is sufficient and pin-compatible replacement is required.
Availability
LM7705MM/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, medical sensor interfaces, and low-voltage split-power supplies requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LM7705MM/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 company specializing in analog and embedded processing technologies, with leadership in precision analog, power management, and signal chain solutions.
The LM7705MM/NOPB belongs to TI's precision negative bias generator product line, engineered specifically to solve true-zero output limitations in single-supply amplifier systems without requiring full dual-rail redesigns.
FAQ
What is the primary function of the LM7705MM/NOPB in amplifier circuits?
The LM7705MM/NOPB generates a regulated −0.232 V negative supply rail to enable true-zero output swing in single-supply rail-to-rail op amps. By providing this small negative bias, it prevents output saturation near ground, allowing amplifiers like the LMP7701 to deliver accurate 0 V signals to ADCs without violating maximum supply differential ratings. This directly improves measurement fidelity in precision sensor interfaces.
How does the LM7705MM/NOPB achieve low output ripple despite using switched-capacitor topology?
The LM7705MM/NOPB achieves 4 mVPP output ripple through integrated pre- and post-regulation stages that filter charge-pump switching noise. Its internal 91–92 kHz oscillator drives external CFLY and CRES capacitors in a controlled sequence, while the post-regulator actively stabilizes VOUT against load and temperature variations. Using recommended 5 µF CFLY and 22 µF CRES values further suppresses ripple to specification.
Can the LM7705MM/NOPB be used with amplifiers rated for ±2.5 V supplies?
Yes - the LM7705MM/NOPB's −0.232 V output is intentionally designed to extend the negative rail of single-supply amplifiers without exceeding their absolute maximum supply differential. When paired with a +2.5 V positive rail, the total 2.732 V differential remains well within the 5.5 V limit specified for many TI op amps (e.g., LMP7701). This avoids costly redesigns while enabling true-zero operation in existing ±2.5 V–rated systems.
What is the significance of the 20 nA shutdown current specification for the LM7705MM/NOPB?
The 20 nA shutdown current allows the LM7705MM/NOPB to minimize system power during idle periods without disconnecting bias rails. When SD is driven HIGH, VOUT is actively pulled to GND and internal circuitry enters ultra-low-power state - critical for battery-operated devices like handheld analyzers or wearables where bias generation accounts for measurable standby drain. This enables duty-cycled operation with µA-level average current consumption.
Does the LM7705MM/NOPB require external compensation components for stability?
No - the LM7705MM/NOPB is internally compensated and requires only three external passive components: a 5 µF CFLY capacitor, a 22 µF CRES capacitor, and a 22 µF COUT capacitor. These values are optimized for stability across the full −40°C to 125°C temperature range and 0–20 mA load current. No additional resistors, feedback networks, or compensation capacitors are needed, simplifying layout and reducing BOM count.
LM7705MM/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:
- Active
- Function:
- Step-Down
- Output Configuration:
- Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 5.25V
- Voltage - Output (Min/Fixed):
- -0.23V
- Voltage - Output (Max):
- -
- Current - Output:
- 26mA
- Frequency - Switching:
- 92kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
LM7705MM/NOPB FAQ
1.How can I place an order for LM7705MM/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM7705MM/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 LM7705MM/NOPB reliable?
The price and inventory of LM7705MM/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM7705MM/NOPB is usually 5 days.
3.What payment methods are accepted for LM7705MM/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM7705MM/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM7705MM/NOPB?
LM7705MM/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM7705MM/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 LM7705MM/NOPB?
For technical support, including LM7705MM/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM7705MM/NOPB requirements.
6.How does Aetrix verify that LM7705MM/NOPB is sourced from the original manufacturer or authorized distributors?
All LM7705MM/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 LM7705MM/NOPB meets industry standards.
7.What is the process for return or replacement of LM7705MM/NOPB?
All LM7705MM/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM7705MM/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 LM7705MM/NOPB part is unused and in its original packaging.
Return procedure for LM7705MM/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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