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Analog Devices Inc./Maxim Integrated MAX861CUA+
- Part No.:
- MAX861CUA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX861CUA+.pdf
- Description:
- IC REG CHARG PUMP INV 50MA 8UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:2,040
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Product details
Overview
MAX861CUA+ from Maxim Integrated is a frequency-selectable, 50mA switched-capacitor voltage inverter/doubler IC that operates from +1.5V to +5.5V (inverter) or +2.5V to +5.5V (doubler), delivering up to –5.5V output or +11V output with <12Ω output resistance, 87% efficiency at 50mA, and 1µA shutdown current. It serves as a compact, inductorless power supply for op-amp rails, portable medical sensors, and interface level-shifting circuits.
For engineers reviewing the MAX861CUA+ datasheet, MAX861CUA+ pinout, MAX861CUA+ application, or MAX861CUA+ equivalent, key selection criteria include its three factory-defined switching frequencies (13/100/250 kHz), LV-controlled mode selection (GND = inverter, OUT = doubler), FC pin configuration options, and µMAX-8 package compatibility with space-constrained PCB layouts.
Technical Context
The MAX861CUA+ implements a BiCMOS charge-pump architecture with direct oscillator-to-switch coupling (no frequency division), enabling precise control of switching frequency via the FC pin. Its internal switch resistance (~8Ω) combines with external capacitor ESR to define total output resistance, which directly impacts load regulation and ripple performance.
Mode selection is determined by the LV pin: tied to GND for inverting operation (VOUT = –VIN), or tied to OUT for doubling (VOUT = +2VIN). The active-low SHDN pin disables all internal circuitry, reducing supply current to <1µA while preserving reverse-current paths depending on load topology.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 50mA max - supports moderate-power analog rails without inductors |
| Switching Frequencies | 13kHz / 100kHz / 250kHz - selectable via FC pin to optimize capacitor size vs. quiescent current |
| Efficiency | 87% at 50mA - enables battery-powered operation with minimal thermal impact |
| Shutdown Current | <1µA - critical for low-power sleep modes in portable instrumentation |
| Output Resistance | 12Ω typical - determines voltage droop: ~0.6V drop at 50mA load from –5V rail |
| Input Voltage Range | +1.5V to +5.5V (inverter); +2.5V to +5.5V (doubler) - compatible with Li-ion, alkaline, and regulated 3.3V/5V supplies |
| Quiescent Current | 200µA typical (MAX860), 300µA typical (MAX861) - measured at VDD = +5V, no load |
Pinout & Package
MAX861CUA+ is housed in an 8-pin µMAX® package (1.11mm height, 3mm × 3mm footprint), RoHS-compliant, with exposed pad for thermal enhancement. Pin 1 is FC; pin 8 is VDD. Package outline U8-1 per Maxim document 21-0036.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FC (Pin 1) | Frequency Control input | Selects switching frequency: FC = VDD → 13kHz; FC = GND → 100kHz; FC = OUT → 250kHz |
| C1+ (Pin 2) | Flying capacitor positive terminal | Connects to one side of flying capacitor C1; carries high-frequency AC current during charge transfer |
| GND (Pin 3) | Ground reference | Primary return path for internal switches and external capacitors; must be low-impedance |
| C1– (Pin 4) | Flying capacitor negative terminal | Connects to opposite side of flying capacitor C1; alternates polarity with each switching cycle |
| OUT (Pin 5) | Output terminal | Delivers inverted (–VIN) or doubled (+2VIN) voltage; connects to reservoir capacitor C2 and load |
| LV (Pin 6) | Mode selection input | LV = GND → inverter mode; LV = OUT → doubler mode; floating not recommended |
| SHDN (Pin 7) | Active-low shutdown control | SHDN < 0.3V → device disabled; SHDN = VDD → enabled; must be tied to VDD if unused in inverter mode |
| VDD (Pin 8) | Positive supply input | Accepts +1.5V to +5.5V (inverter) or +2.5V to +5.5V (doubler); powers internal oscillator and switches |
Key Features
| Feature | Design Value |
|---|---|
| Invert or double input voltage | Single IC supports both topologies via LV pin configuration-eliminates need for separate inverter/doubler parts |
| Three selectable switching frequencies | Enables trade-off between capacitor size (higher fS → smaller C1/C2) and quiescent current (lower fS → lower IDD) |
| 12Ω output resistance | Ensures predictable load regulation: e.g., –5.0V → –4.4V at 50mA, simplifying rail design for op-amps and ADCs |
| 1µA shutdown current | Extends battery life in handheld instruments by disabling >99.9% of internal current draw |
| µMAX-8 package | 3mm × 3mm footprint with 0.5mm pitch enables high-density layout in portable medical and test equipment |
Applications
| Portable Medical Sensors | Operational Amplifier Power Rails |
|---|---|
Use Scenario: Powering dual-rail op-amps in battery-operated ECG front-ends requiring ±5V from a single 5V supply. IC Role / Device Role / Timing Role: MAX861CUA+ acts as a compact, inductorless negative rail generator, configured in inverter mode (LV = GND). Use Value: Eliminates magnetic interference from inductors, reduces board area by >40% vs. inductive solutions, and maintains stable –4.8V output under 20mA sensor bias loads. | Use Scenario: Generating split supplies for precision instrumentation amplifiers in handheld multimeters. IC Role / Device Role / Timing Role: MAX861CUA+ provides isolated negative rail in inverter mode, synchronized to system clock via FC pin to avoid noise coupling into analog signal chain. Use Value: Achieves <10mVpp output ripple using 4.7µF ceramic C1/C2 at 250kHz, meeting EN61000-4-3 immunity requirements for Class II portable devices. |
| Interface Level Shifting | Hand-Held Test Equipment |
Use Scenario: Converting 3.3V logic signals to ±10V RS-232 levels in compact USB-to-serial adapters. IC Role / Device Role / Timing Role: MAX861CUA+ operates in doubler mode (LV = OUT) to generate +6.6V, then cascades with second MAX861CUA+ to reach +13.2V for driver stage. Use Value: Enables full-duplex RS-232 compliance without external transformers or charge pumps with higher quiescent current (>500µA). | Use Scenario: Supplying ±4.5V rails for analog front-end of portable oscilloscope probes. IC Role / Device Role / Timing Role: Two parallel MAX861CUA+ units reduce effective output resistance to ~6Ω, supporting 40mA peak current during transient signal acquisition. Use Value: Delivers <1% line regulation over 3.0–5.5V input range, ensuring consistent probe gain calibration across battery discharge cycle. |
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 |
|---|---|---|---|
| MAX860CUA+ | Shares identical pinout, package, and functional architecture; differs only in factory-set FC frequency set (6/50/130 kHz vs. 13/100/250 kHz) | Better suited for ultra-low-noise applications where 6kHz fundamental switching frequency must be avoided | Select MAX860CUA+ when lowest possible quiescent current (<200µA) and sub-10kHz noise floor are required |
| MAX660CPA+ | Higher 100mA output, 6.5Ω output resistance, but fixed 5kHz/40kHz frequencies and no FC/LV pins | Requires external resistors for mode selection; lacks frequency flexibility and shutdown control | Choose MAX660CPA+ only when higher current (>50mA) and simpler control interface outweigh need for frequency optimization |
Compared with MAX860CUA+, the MAX861CUA+ offers higher switching frequencies for reduced capacitor size and better noise avoidance, while MAX660CPA+ provides greater output current at the cost of configurability and modern low-power features.
Availability
MAX861CUA+ is available at Aetrix Electronics and suitable for portable medical sensors, operational-amplifier power rails, interface level shifting, and hand-held test equipment requiring stable component supply and long-term industrial availability.
Supply support for MAX861CUA+ 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
Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.
The MAX860/MAX861 product line delivers compact, inductorless DC-DC conversion for space- and power-constrained systems where electromagnetic compatibility and board area are critical constraints.
FAQ
What is the maximum output current capability of the MAX861CUA+?
The MAX861CUA+ delivers up to 50mA continuous output current in both inverter and doubler configurations. Absolute maximum ratings specify 60mA, but sustained operation above 50mA may exceed thermal limits in the µMAX package. Derating is required above +70°C ambient, with 4.2mW/°C reduction in power dissipation. Performance data in the datasheet confirms stable regulation and 87% efficiency at 50mA load with 10µF capacitors.
How does the LV pin affect MAX861CUA+ operation?
The LV pin on the MAX861CUA+ selects operating mode: connecting LV to GND configures the device as a voltage inverter (VOUT ≈ –VIN), while connecting LV to OUT configures it as a voltage doubler (VOUT ≈ +2VIN). Floating LV is not recommended. In doubler mode, the minimum input voltage increases to +2.5V, and the no-load supply current rises slightly compared to inverter mode. This pin enables hardware-selectable topology without firmware or external logic.
Can the MAX861CUA+ be used as a direct replacement for the ICL7660?
The MAX861CUA+ is pin-compatible with the ICL7660 in 8-pin SO and µMAX packages but requires one wiring change: the ICL7660's OSC pin maps to the MAX861CUA+'s FC pin, and the ICL7660's unused pin 7 must be tied to VDD (not left floating) to enable the MAX861CUA+. Unlike the ICL7660's fixed 5kHz frequency, the MAX861CUA+ offers three selectable frequencies (13/100/250 kHz), enabling optimized capacitor sizing and noise avoidance.
What are the recommended capacitor values for MAX861CUA+ in high-frequency mode?
For MAX861CUA+ operating at 250kHz (FC = OUT), Table 3 in the datasheet recommends 2.2µF for both C1 (flying capacitor) and C2 (output reservoir capacitor). Low-ESR ceramic or tantalum types are required; aluminum electrolytics with ESR >0.2Ω degrade output resistance and efficiency. Using 2.2µF at 250kHz achieves <10mVpp ripple at 20mA load and maintains 85% efficiency-smaller than the 10µF needed at 13kHz, saving >70% board area.
Does the MAX861CUA+ require a bypass capacitor on the VDD supply?
Yes, a bypass capacitor is required on the VDD supply of the MAX861CUA+. When loaded from OUT to GND (inverter) or VDD to GND (doubler), the input current switches between 0 and 2×IOUT, demanding a large bypass capacitor (≥10µF, low-ESR) to suppress supply ripple and prevent brownout. When loaded from VDD to OUT, a 0.1µF ceramic capacitor suffices. Failure to bypass properly causes startup failure or erratic shutdown behavior due to VDD sag during high-current charge cycles.
MAX861CUA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Ratiometric
- Output Configuration:
- Positive or Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.5V, 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- -Vin, 2Vin
- Voltage - Output (Max):
- -
- Current - Output:
- 50mA
- Frequency - Switching:
- 13kHz, 100kHz, 250kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-uMAX/uSOP
MAX861CUA+ FAQ
1.How can I place an order for MAX861CUA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX861CUA+ 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 MAX861CUA+ reliable?
The price and inventory of MAX861CUA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX861CUA+ is usually 5 days.
3.What payment methods are accepted for MAX861CUA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX861CUA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX861CUA+?
MAX861CUA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX861CUA+ 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 MAX861CUA+?
For technical support, including MAX861CUA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX861CUA+ requirements.
6.How does Aetrix verify that MAX861CUA+ is sourced from the original manufacturer or authorized distributors?
All MAX861CUA+ 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 MAX861CUA+ meets industry standards.
7.What is the process for return or replacement of MAX861CUA+?
All MAX861CUA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX861CUA+, 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 MAX861CUA+ part is unused and in its original packaging.
Return procedure for MAX861CUA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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