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Texas Instruments LM7705MME/NOPB
- Part No.:
- LM7705MME/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM7705MME/NOPB.pdf
- Description:
- IC REG CHARGE PUMP -0.23V 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:41,583
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Product details
Overview
LM7705MME/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 amplifiers by supplying a small negative rail without exceeding amplifier absolute maximum ratings-used in precision sensor signal chains feeding 12-bit ADCs.
For engineers reviewing the LM7705MME/NOPB datasheet, LM7705MME/NOPB pinout, LM7705MME/NOPB application, or LM7705MME/NOPB equivalent, key selection criteria include its fixed −0.23 V output voltage, shutdown current of 20 nA, 78 µA quiescent current, 500 µs turn-on time, and compatibility with rail-to-rail op amps requiring sub-50 mV saturation margin at ground.
Technical Context
The LM7705MME/NOPB integrates a pre-regulator, charge-pump inverter, and post-regulator to generate a stable −0.232 V output from a single positive supply. Its internal oscillator operates at ~92 kHz and drives complementary switch pairs (S1/S2, S3/S4) to transfer charge between CFLY and CRES capacitors, enabling voltage inversion without inductors.
It supports shutdown control via a logic-level SD pin (VIH ≥ 2.15 V at 5 V, VIL ≤ 1.95 V), reducing supply current to 20 nA. Output impedance remains ≤0.8 Ω over −1 mA to −20 mA load range, and line regulation is specified at 0.29%/V-critical for maintaining accuracy across varying input voltages in portable instrumentation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −0.232 V ±5% - precisely calibrated to bias amplifier negative rails while staying within typical op amp abs max ratings (e.g., ±6 V differential). |
| Output Ripple | 4 mVPP at −20 mA - low enough to avoid introducing measurable offset or noise in high-resolution (12-bit) analog signal paths. |
| Supply Range | 3 V to 5.25 V - compatible with standard Li-ion, USB, and LDO-powered systems without external level shifting. |
| Quiescent Current | 78 µA at 3.3 V - enables battery life extension in always-on portable instrumentation with minimal standby drain. |
| Shutdown Current | 20 nA - allows full system power gating during sleep modes without compromising wake-up latency or residual leakage. |
| Turn-on Time | 500 µs at 3.3 V - ensures rapid stabilization before ADC sampling windows in burst-mode sensor acquisition. |
| Efficiency | 98% at −5 mA - minimizes thermal rise and input supply loading in space-constrained PCB layouts. |
Pinout & Package
LM7705MME/NOPB uses an 8-pin VSSOP package (3.00 mm × 3.00 mm body size) with exposed thermal pad (DGK suffix). Pin functions are validated per TI SNVS420D Rev D datasheet.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CF+ | CFLY capacitor positive terminal | Connects to flying capacitor (CFLY); forms charge-transfer path with CF− during oscillator phase transitions. |
| VSS | Power ground | Dual ground pins (2 & 5) reduce ground loop impedance and improve PSRR in noise-sensitive analog sections. |
| SD | Shutdown control input | Active-low enable: logic LOW (≤1.95 V) activates device; HIGH (≥2.15 V) forces output to ground and draws 20 nA. |
| VDD | Positive supply input | Accepts 3 V–5.25 V; powers internal regulators, oscillator, and switch drivers-no external decoupling beyond COUT required. |
| VOUT | Negative regulated output | Delivers −0.232 V to amplifier V− pin; capable of sinking up to −20 mA with <0.8 Ω output impedance. |
| CRES | Reserve capacitor connection | Stabilizes post-regulator output; value (22 µF typical) directly impacts ripple magnitude and transient response. |
| CF− | CFLY capacitor negative terminal | Completes flying capacitor loop; paired with CF+ to enable bidirectional charge pumping at 92 kHz. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed −0.232 V output | Eliminates need for external feedback resistors or trimming-ensures consistent zero-reference across temperature (−40°C to 125°C). |
| Low-noise architecture | 4 mVPP ripple at full load prevents gain-stage error accumulation in multi-op-amp signal chains feeding high-resolution ADCs. |
| Integrated pre- and post-regulation | Compensates for charge-pump variation across input voltage and load, achieving 0.29%/V line regulation and 0.14%/mA load regulation. |
| Ultra-low shutdown current | 20 nA enables >10-year battery life in maintenance-free IoT sensor nodes using periodic wake-up cycles. |
| VSSOP-8 thermal design | 3 mm × 3 mm footprint with thermal pad supports >100 mW dissipation-sufficient for continuous −20 mA operation at 125°C ambient. |
Applications
| Portable Instrumentation | True Zero Amplifier Outputs |
|---|---|
Use Scenario: Handheld pH meter with single-supply rail-to-rail op amp conditioning microvolt-level electrode signals before 12-bit SAR ADC digitization. IC Role / Device Role / Timing Role: LM7705MME/NOPB supplies −0.232 V to op amp V− pin, enabling output swing to true 0 V and preserving full ADC dynamic range. Use Value: Recovers 400+ lost ADC codes otherwise clipped by 50 mV op amp saturation-improving measurement resolution by >3 bits without redesigning front-end supply. |
Use Scenario: Medical ECG front-end using dual LMP7702 op amps in DC-coupled two-stage configuration to amplify sub-mV biopotentials. IC Role / Device Role / Timing Role: LM7705MME/NOPB provides stabilized negative bias to both amplifier stages, preventing cumulative saturation offset propagation. Use Value: Reduces total output offset from >500 mV (without bias) to <10 mV-enabling accurate baseline recovery and eliminating software calibration overhead. |
| Low-Voltage Split-Power Supplies | Industrial Sensor Signal Conditioning |
Use Scenario: Battery-powered gas detector with 3.3 V MCU and analog front-end requiring ±2.5 V rails for precision transimpedance amplification. IC Role / Device Role / Timing Role: LM7705MME/NOPB generates −0.232 V rail to extend effective negative headroom of single 3.3 V supply for rail-to-rail op amps. Use Value: Avoids cost and board area penalty of discrete inductor-based inverter or dual-LDO solution-maintains BOM simplicity and EMI compliance. |
Use Scenario: 4–20 mA loop-powered temperature transmitter using single-supply op amp to condition RTD bridge output before DAC-driven current output stage. IC Role / Device Role / Timing Role: LM7705MME/NOPB biases op amp V− to −0.232 V, ensuring linear 0–100 °C output mapping down to true 0 V reference. Use Value: Enables full-scale 0–100 °C reporting with <±0.1 °C error-meeting Class A RTD accuracy requirements without external negative supply. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative bias generator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1682ESA+ | Generates −2×VIN (e.g., −6.6 V from 3.3 V); no internal regulation; higher ripple (15 mVPP) and quiescent current (120 µA). | Suitable for general-purpose inverting supplies but not precision zero-biasing-requires external LDO for −0.23 V output. | Select MAX1682ESA+ only when higher negative voltage is needed and regulation/ripple are secondary concerns. |
| TPS60403DBVR | Adjustable output (−1.5 V to −5.5 V); requires external feedback resistors; 10 mVPP ripple; 110 µA IQ. | Flexible for multi-rail systems but lacks factory-trimmed −0.23 V accuracy-needs calibration to match LM7705MME/NOPB's zero-reference precision. | Choose TPS60403DBVR if system requires programmable negative rails and can accommodate resistor network layout and calibration. |
Compared with MAX1682ESA+ and TPS60403DBVR, LM7705MME/NOPB delivers superior zero-reference accuracy and lower noise without external components-making it optimal for true-zero amplifier biasing where output voltage tolerance and ripple directly impact measurement fidelity.
Availability
LM7705MME/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, true zero amplifier outputs, and low-voltage split-power supplies requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LM7705MME/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 LM7705MME/NOPB belongs to TI's precision negative bias generator product line, designed specifically to solve true-zero output limitations in single-supply amplifier applications-targeting medical, test & measurement, and industrial sensor systems.
FAQ
What is the exact regulated output voltage of the LM7705MME/NOPB?
The LM7705MME/NOPB delivers a factory-trimmed, regulated output voltage of −0.232 V with ±5% tolerance across −40°C to 125°C. This value is confirmed in TI's SNVS420D datasheet Section 6.5 and 6.6, and is maintained by integrated pre- and post-regulators-not dependent on external components or load conditions up to −20 mA.
Does the LM7705MME/NOPB require external capacitors, and what values are recommended?
Yes, LM7705MME/NOPB requires three external capacitors: 5 µF CFLY (between CF+ and CF−), 22 µF CRES (between CRES and VSS), and 22 µF COUT (between VOUT and VSS). These values are validated in TI's datasheet Sections 6.5–6.6 and Figure 8, ensuring specified 4 mVPP ripple and stability across temperature and load.
How does the shutdown function operate on the LM7705MME/NOPB?
The LM7705MME/NOPB shutdown pin (SD) is active-low: applying ≤1.95 V (at 5 V supply) enables the device, while ≥2.15 V disables it-pulling VOUT to ground and reducing supply current to 20 nA. This behavior is fully characterized in Section 6.5 VIH/VIL specs and functional description Section 7.4.1.
Can the LM7705MME/NOPB drive a −20 mA load while maintaining regulation?
Yes, LM7705MME/NOPB maintains −0.232 V output within ±5% tolerance at −20 mA load, with output impedance ≤0.8 Ω (25°C) and load regulation of 0.14%/mA. These performance limits are verified in TI's 3.3-V and 5-V Electrical Characteristics tables (Sections 6.5–6.6) and Figure 3–4.
What is the operating temperature range for the LM7705MME/NOPB?
The LM7705MME/NOPB is rated for continuous operation from −40°C to +125°C ambient temperature. All key specifications-including output voltage, ripple, quiescent current, and efficiency-are guaranteed across this full range per Sections 6.3 and 6.5–6.6 of the official TI datasheet SNVS420D.
LM7705MME/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
LM7705MME/NOPB FAQ
1.How can I place an order for LM7705MME/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM7705MME/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 LM7705MME/NOPB reliable?
The price and inventory of LM7705MME/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM7705MME/NOPB is usually 5 days.
3.What payment methods are accepted for LM7705MME/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM7705MME/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM7705MME/NOPB?
LM7705MME/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM7705MME/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 LM7705MME/NOPB?
For technical support, including LM7705MME/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM7705MME/NOPB requirements.
6.How does Aetrix verify that LM7705MME/NOPB is sourced from the original manufacturer or authorized distributors?
All LM7705MME/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 LM7705MME/NOPB meets industry standards.
7.What is the process for return or replacement of LM7705MME/NOPB?
All LM7705MME/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM7705MME/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 LM7705MME/NOPB part is unused and in its original packaging.
Return procedure for LM7705MME/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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