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Texas Instruments LMC7660IN
- Part No.:
- LMC7660IN
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LMC7660IN.pdf
- Description:
- IC REG CHARGE PUMP 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,702
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Product details
Overview
LMC7660IN from Texas Instruments is a CMOS switched-capacitor voltage converter that inverts +1.5V to +10V input to −1.5V to −10V output without external diodes, delivers 97% voltage conversion efficiency, features 10 kHz internal oscillator, and operates across −40°C to +85°C for rail-splitting and dual-supply generation in portable instrumentation.
For engineers reviewing the LMC7660IN datasheet, LMC7660IN pinout, LMC7660IN application, or LMC7660IN equivalent, this device is selected for low-quiescent-current (200 μA max) negative supply generation where space-constrained designs require only two external electrolytic capacitors and no diode overhead.
Technical Context
The LMC7660IN uses an internal RC oscillator and ÷2 divider to drive four CMOS power switches (S1–S4) in complementary half-cycle phases, enabling charge-pump inversion without external rectification. Its substrate-level logic prevents latchup by dynamically biasing p-wells-S4's p-well held at lowest potential ensures safe operation down to 1.5V supply.
It supports LV-mode optimization (pin 6 grounded for V+ ≤3.5V) and external clock synchronization (pin 7), allowing frequency scaling from ~100 Hz to 20 kHz. Output impedance is actively managed via internal switch Ron and externally sized Cp/Cr capacitors, with typical Rout = 55 Ω at 20 mA load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Range | +1.5V to +10V - enables direct battery (2×AA/AAA) or logic-rail (3.3V/5V) operation without boost stages |
| Output Range | −1.5V to −10V - precise inverted rail matching input magnitude, usable for op-amp dual supplies |
| Voltage Efficiency | ≥97% (no load) - minimizes energy loss during charge transfer, critical for battery runtime extension |
| Oscillator Freq | 10 kHz nominal - sets base switching rate; adjustable downward with Cosc to reduce IQ to ~10 μA |
| Supply Current | 120 μA typ / 200 μA max - ultra-low quiescent draw supports μPower systems like handheld meters |
| Output Resistance | 55 Ω typ at 20 mA - defines load regulation and ripple under dynamic current; improves with parallel devices |
| Operating Temp | −40°C to +85°C - industrial-grade thermal range validated across full voltage span without external diode |
Pinout & Package
LMC7660IN is housed in an 8-pin PDIP package (Package Drawing P), 0.300″ wide, RoHS-compliant, with 1.27 mm lead pitch and through-hole mounting compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (V+) | Positive Input Supply | Accepts +1.5V to +10V; powers internal oscillator, regulator, and switches |
| 2 (GND) | Ground Reference | System ground return; substrate reference for all internal p-wells and level translators |
| 3 (Cp) | Pump Capacitor Terminal | Connects to positive plate of external pump capacitor Cp; switched between V+ and GND |
| 4 (Cr) | Reservoir Capacitor Terminal | Connects to negative plate of reservoir capacitor Cr; develops final −V+ output |
| 5 (LV) | Low-Voltage Mode Control | Ground for V+ ≤3.5V to improve startup and efficiency; leave open for V+ ≥3.5V |
| 6 (OSC) | Oscillator Timing Node | Internal RC node; add external Cosc to reduce frequency and quiescent current |
| 7 (CLK) | External Clock Input | Overrides internal oscillator; accepts CMOS-level clock; output pumping rate = fCLK/2 |
| 8 (V−) | Negative Output | Delivers regulated −V+; requires external Cr capacitor; max |IOUT| ≈ 20 mA continuous |
Key Features
| Feature | Design Value |
|---|---|
| No-external-diode inversion | Eliminates series diode drop and conduction loss, preserving full −V+ amplitude and reducing output impedance |
| Pin-for-pin 7660 replacement | Direct drop-in upgrade for legacy ICL7660/7660A designs without PCB changes or layout rework |
| Adjustable oscillator frequency | External Cosc scales fOSC from 10 kHz down to ~100 Hz, cutting supply current to single-digit μA |
| LV mode optimization | Pin 6 grounding below 3.5V improves startup reliability and conversion efficiency in low-voltage battery apps |
| Parallel-ready architecture | Multiple LMC7660IN units can share Cr while using individual Cp, lowering composite output resistance |
Applications
| Portable Instrumentation Power | Rail-Splitting for Single-Supply Op-Amps |
|---|---|
|
Use Scenario: Handheld multimeter or pH meter powered by two 1.5V alkaline cells (3V total), requiring ±1.5V analog front-end rails. IC Role / Device Role / Timing Role: LMC7660IN generates stable −1.5V from the 3V supply using Cp = 10 μF and Cr = 100 μF electrolytics; internal 10 kHz oscillator provides fixed timing. Use Value: Delivers 97% voltage efficiency and 55 Ω output impedance, enabling <10 mV ripple at 5 mA load-sufficient for 16-bit ADC reference buffers. |
Use Scenario: Single-supply audio amplifier (e.g., TPA6130) needing symmetrical ±2.5V rails from a 5V system bus. IC Role / Device Role / Timing Role: LMC7660IN inverts 5V to −5V; Cr capacitor forms mid-rail virtual ground via resistor divider, creating true ±2.5V split. Use Value: Achieves <±1% rail balance error over temperature due to matched internal switch Ron and absence of diode VF drift. |
| μPower Sensor Signal Conditioning | Battery-Backed RTC and Memory Bias |
|
Use Scenario: Wireless temperature sensor node (LM35 + CC2530) operating on coin cell, requiring negative bias for precision op-amp offset nulling. IC Role / Device Role / Timing Role: LMC7660IN configured with Cosc = 100 nF reduces oscillator frequency to ~200 Hz, cutting IQ to 15 μA during sleep. Use Value: Extends CR2032 battery life from 6 to >24 months by minimizing idle current while maintaining −1.25V bias accuracy within ±20 mV. |
Use Scenario: Industrial PLC with real-time clock (DS1307) and SRAM backup, needing −3V bias for write-protection circuitry during main power loss. IC Role / Device Role / Timing Role: LMC7660IN powered from supercapacitor backup rail (3.3V); pin 7 tied to microcontroller wake-up signal for synchronized shutdown. Use Value: Provides regulated −3.3V output with <50 μs turn-on delay, ensuring glitch-free SRAM write-enable during brownout transitions. |
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 |
|---|---|---|---|
| ICL7660CPA | Requires external diode for latchup prevention above 2.5V; higher 300 μA max IQ; no LV mode pin | Legacy designs only; unsuitable for battery-powered systems below 3.5V without redesign | Select only if replacing existing ICL7660-based boards where diode footprint exists and low IQ is non-critical |
| MAX680CPA | Higher 125 kHz oscillator; 120 μA max IQ; integrated charge-pump driver; no LV control pin | Better high-frequency ripple suppression but incompatible pinout; requires different Cp/Cr values | Prefer when fast transient response and lower output impedance (<20 Ω) are required, and board layout allows rework |
Compared with ICL7660CPA, LMC7660IN eliminates diode dependency and cuts quiescent current by 33%; versus MAX680CPA, it offers pin compatibility with legacy 7660 footprints and superior low-voltage startup-but trades off higher output impedance and lower switching frequency.
Availability
LMC7660IN is available at Aetrix Electronics and suitable for portable instrumentation, rail-splitting, μPower sensor conditioning, battery-backed memory bias, and industrial analog front-end power requiring stable component supply with long-term lifecycle support.
Supply support for LMC7660IN 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, precision, and energy efficiency.
The LMC7660IN belongs to TI's precision analog switched-capacitor converter product line, engineered specifically for low-power, space-constrained DC/DC inversion where simplicity, diode-free operation, and wide input voltage range are critical.
FAQ
What is the maximum continuous output current capability of the LMC7660IN?
The LMC7660IN delivers up to 20 mA continuous output current into a resistive load while maintaining voltage regulation and efficiency. At 20 mA, typical output source resistance is 55 Ω, resulting in ~1.1 V drop-so for a −5V target, minimum V+ must be ≥6.1V. Derating is required above 85°C ambient per θJA = 90°C/W.
Can the LMC7660IN operate from a 1.8V supply, and what configuration is required?
Yes, the LMC7660IN supports 1.5V minimum supply, including 1.8V operation. For reliable startup and optimal efficiency at V+ ≤3.5V, pin 6 (LV) must be shorted to ground. Leaving LV open at 1.8V risks incomplete switching and reduced voltage conversion efficiency-TI specifies LV-grounding as mandatory below 3.5V.
Does the LMC7660IN require external diodes, and how does it prevent latchup?
No, the LMC7660IN does not require external diodes. It prevents destructive latchup via proprietary substrate-level logic that dynamically biases the p-wells of internal N-channel switches S3 and S4-ensuring S4's p-well remains at the lowest potential in the circuit under all operating conditions, eliminating parasitic SCR activation.
How do I reduce output ripple on the LMC7660IN for a 10 mA load?
To reduce output ripple at 10 mA, increase the reservoir capacitor Cr value-e.g., from 10 μF to 47 μF or 100 μF low-ESR electrolytic-and ensure Cp ≥ Cr. Ripple scales inversely with Cr and fOSC; lowering oscillator frequency with Cosc increases ripple unless Cr is proportionally increased. TI's Equation (2) gives Cr ≈ (ILOAD × T)/ΔVPP.
Is the LMC7660IN pin-compatible with the ICL7660, and are there any layout considerations?
Yes, the LMC7660IN is fully pin-compatible with the ICL7660 in PDIP-8 packages, sharing identical pinout, footprint, and terminal functions. Layout requires no changes-however, remove any series output diode used in legacy ICL7660 designs, as the LMC7660IN's internal architecture eliminates its need and restores full −V+ amplitude.
LMC7660IN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Ratiometric
- Output Configuration:
- Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.5V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- -Vin
- Voltage - Output (Max):
- -
- Current - Output:
- -
- Frequency - Switching:
- 10kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LMC7660IN FAQ
1.How can I place an order for LMC7660IN through Aetrix?
Please submit a Request for Quotation (RFQ) for LMC7660IN 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 LMC7660IN reliable?
The price and inventory of LMC7660IN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMC7660IN is usually 5 days.
3.What payment methods are accepted for LMC7660IN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMC7660IN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMC7660IN?
LMC7660IN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMC7660IN 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 LMC7660IN?
For technical support, including LMC7660IN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMC7660IN requirements.
6.How does Aetrix verify that LMC7660IN is sourced from the original manufacturer or authorized distributors?
All LMC7660IN 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 LMC7660IN meets industry standards.
7.What is the process for return or replacement of LMC7660IN?
All LMC7660IN units undergo pre-shipment inspection (PSI). If there is an issue with LMC7660IN, 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 LMC7660IN part is unused and in its original packaging.
Return procedure for LMC7660IN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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