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Analog Devices Inc./Maxim Integrated MAX861IUA+
- Part No.:
- MAX861IUA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX861IUA+.pdf
- Description:
- IC REG CHARG PUMP INV 50MA 8UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:438
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Product details
Overview
MAX861IUA+ from Maxim Integrated is a frequency-selectable, 50mA switched-capacitor voltage inverter/doubler IC designed for low-noise, inductorless DC-DC conversion in space-constrained systems. It operates from +1.5V to +5.5V (inverter) or +2.5V to +5.5V (doubler), delivers ≥87% efficiency at 50mA, and features three user-selectable switching frequencies (13/100/250 kHz) via the FC pin - enabling optimized capacitor sizing and EMI mitigation in portable medical instruments and handheld test equipment.
For engineers reviewing the MAX861IUA+ datasheet, MAX861IUA+ pinout, MAX861IUA+ application, or MAX861IUA+ equivalent, key selection criteria include its 12Ω output resistance, 1µA shutdown current, LV pin configuration dependency on mode (GND for inverter, OUT for doubler), and µMAX-8 package compatibility with legacy ICL7660/MAX660 footprints requiring only SHDN pin reconnection.
Technical Context
The MAX861IUA+ implements a BiCMOS charge-pump architecture with direct oscillator-to-switch coupling (no frequency division), supporting both inverting (VOUT ≈ –VIN) and doubling (VOUT ≈ +2VIN) topologies. Its LV pin determines mode: grounded for inversion, tied to OUT for doubling - altering input voltage range and internal switch routing without external component changes.
Switching frequency is set unambiguously by FC pin voltage: FC = VDD → 13kHz, FC = GND → 100kHz, FC = OUT → 250kHz. Each setting trades off quiescent current (lower at 13kHz), capacitor size (smaller at 250kHz), and output ripple (reduced at higher fS), with no overlap or ambiguity between modes or frequency states.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 50mA continuous - supports rail-splitting for dual-supply op-amps without inductors. |
| Switching Frequencies | 13/100/250 kHz - enables EMI avoidance in sensitive analog sections and reduces flying capacitor size to 2.2µF at highest frequency. |
| Efficiency | 87% at 50mA load - minimizes thermal rise in sealed portable enclosures. |
| Shutdown Current | <1µA - extends battery life in intermittent-use medical sensors. |
| Output Resistance | 12Ω (typical) - causes ≤600mV drop at 50mA, enabling predictable voltage regulation via feedback-free design. |
| Input Voltage Range | +1.5V to +5.5V (inverter), +2.5V to +5.5V (doubler) - matches Li-ion, alkaline, and regulated 3.3V/5V rails. |
| Quiescent Current | 200µA (typical) - allows operation from coin-cell batteries for >1 year in low-duty-cycle applications. |
Pinout & Package
MAX861IUA+ 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. The package is pin-compatible with SO-8 but requires µMAX-specific PCB land pattern (Maxim land pattern #90-0092).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FC (Pin 1) | Frequency control input | Voltage-selectable oscillator: VDD=13kHz, GND=100kHz, OUT=250kHz - sets noise spectrum and capacitor sizing. |
| C1+ (Pin 2) | Flying capacitor positive terminal | Drives charge transfer cycle; connects to C1 anode in standard inverter/doubler configurations. |
| GND (Pin 3) | Ground reference | Common return for all internal circuitry and external capacitors; must be low-impedance for ripple control. |
| C1− (Pin 4) | Flying capacitor negative terminal | Completes charge-pump switching path; polarity reversal defines inverter vs. doubler topology. |
| OUT (Pin 5) | Output voltage node | Delivers inverted (–VIN) or doubled (+2VIN) voltage; connects to reservoir capacitor C2 and load. |
| LV (Pin 6) | Mode selection input | GND = inverter mode (+1.5V–5.5V input); OUT = doubler mode (+2.5V–5.5V input) - configures internal switch matrix. |
| SHDN (Pin 7) | Active-low shutdown control | Pulled high to VDD for normal operation; driven low to reduce supply current to <1µA - critical for power gating. |
| VDD (Pin 8) | Positive supply input | Accepts +1.5V to +5.5V; powers all internal circuitry and supplies charge to flying capacitor C1. |
Key Features
| Feature | Design Value |
|---|---|
| Inverter/doubler dual-mode operation | Single IC replaces two discrete converters - reduces BOM count and board area in multi-rail systems. |
| Three-frequency selection | Enables EMI compliance in RF-sensitive designs (e.g., ECG front-ends) by shifting fundamental noise away from critical bands. |
| 12Ω output resistance | Provides predictable load regulation (≤600mV drop at 50mA) without feedback loop complexity or external compensation. |
| 1µA shutdown current | Supports ultra-low-power sleep states in battery-powered handheld instruments with wake-on-interrupt capability. |
| µMAX-8 package | 3mm × 3mm footprint with 1.11mm height - fits beneath 0.8mm-thick display bezels in portable diagnostics devices. |
Applications
| Portable Medical Sensors | Handheld Test Equipment |
|---|---|
|
Use Scenario: Powering dual-supply instrumentation amplifiers in battery-operated ECG/EEG monitors. IC Role / Device Role / Timing Role: Inverter generating –3.3V from +3.3V main rail to establish symmetric ±3.3V analog supply. Use Value: Eliminates inductors that cause magnetic interference with sensitive bio-signal acquisition, while maintaining 87% efficiency at 20mA typical load. |
Use Scenario: Providing negative bias for LCD contrast control and op-amp rails in field-deployable multimeters. IC Role / Device Role / Timing Role: Doubler generating +10V from +5V microcontroller rail to drive LCD backlights and analog front-end references. Use Value: Enables single-battery operation (2×AA) without external boost converters, reducing bill-of-materials cost by $0.32 per unit. |
| Interface Power Supplies | Operational-Amplifier Power Supplies |
|
Use Scenario: Generating isolated –5V for RS-232 transceivers in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Inverter operating at 100kHz (FC=GND) to minimize 10µF flying capacitor size while avoiding 32kHz audio-band noise. Use Value: Meets TIA-232E voltage swing requirements (±5V ±5%) under 10mA load with ≤120mV ripple, verified across –25°C to +85°C. |
Use Scenario: Supplying ±15V rails for precision op-amps in automated test equipment signal sources. IC Role / Device Role / Timing Role: Cascaded MAX861IUA+ pair (Figure 1) delivering –30V from +15V input for high-voltage DAC buffers. Use Value: Achieves 5× lower output resistance than single-device solution, enabling 10mA sourcing into 1kΩ loads with <1% line regulation. |
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 |
|---|---|---|---|
| MAX860IUA+ | Shares identical µMAX-8 package, pinout, and 6/50/130kHz frequency options; 200µA quiescent current vs. 200µA for MAX861IUA+. | Optimized for lower-frequency EMI environments (e.g., audio codecs) where 130kHz max switching suffices. | Select MAX860IUA+ when system noise floor requires fundamental switching frequency ≤130kHz and 50mA output meets requirement. |
| MAX660CPA+ | SO-8 package, 100mA output, 5/40kHz frequencies, 6.5Ω output resistance; higher current but lower frequency and larger solution size. | Suitable for higher-current, lower-frequency applications (e.g., legacy industrial controllers) where µMAX footprint is not required. | Choose MAX660CPA+ only if >50mA output or compatibility with existing SO-8 layouts is mandatory - not a drop-in replacement for MAX861IUA+. |
Compared with MAX860IUA+, MAX861IUA+ provides higher-frequency options (up to 250kHz) for smaller capacitors and better EMI control, while MAX660CPA+ offers higher output current at the cost of larger size and lower switching frequencies - making MAX861IUA+ optimal for compact, noise-sensitive portable designs demanding 50mA.
Availability
MAX861IUA+ is available at Aetrix Electronics and suitable for portable medical sensors, handheld test equipment, interface power supplies, and operational-amplifier power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MAX861IUA+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.
The MAX860/MAX861 product line was engineered to replace inductive DC-DC converters in space-constrained, low-EMI applications - targeting portable instrumentation, battery-powered sensors, and interface power where inductor size, cost, and magnetic emissions are prohibitive.
FAQ
What are the valid input voltage ranges for MAX861IUA+ in inverter vs. doubler mode?
The MAX861IUA+ accepts +1.5V to +5.5V when configured as an inverter (LV = GND), and +2.5V to +5.5V when configured as a doubler (LV = OUT). These ranges are strictly enforced by internal circuit design - applying 2.0V to the doubler mode will result in insufficient output voltage and potential instability. Always verify LV connection matches the desired topology before power-up.
How does the FC pin select switching frequency on MAX861IUA+?
The FC pin on MAX861IUA+ selects one of three discrete frequencies: 13kHz when tied to VDD, 100kHz when tied to GND, and 250kHz when tied to OUT. Unlike resistor-programmed oscillators, this is a digital selection - no intermediate values are possible. The selected frequency directly determines flying capacitor size (e.g., 2.2µF at 250kHz vs. 68µF at 13kHz) and impacts both quiescent current and output ripple.
Can MAX861IUA+ be used as a direct replacement for ICL7660 in existing designs?
MAX861IUA+ can replace ICL7660 in SO-8 layouts with one wiring change: the ICL7660's OSC pin (floating in normal operation) maps to MAX861IUA+'s SHDN pin, which must be pulled high to VDD (not left floating) for enabled operation. All other pins align functionally, and the higher 250kHz max frequency improves capacitor sizing - but verify LV pin connection matches original topology.
What is the maximum continuous output current specification for MAX861IUA+?
The MAX861IUA+ is rated for 50mA continuous output current under all operating conditions specified in the datasheet (TA = –25°C to +85°C, VDD = +5V, C1/C2 = 10µF). Exceeding 50mA risks thermal overload and voltage droop beyond specifications; the absolute maximum rating is 60mA, but sustained operation above 50mA is not guaranteed across temperature or input voltage ranges.
How does LV pin configuration affect MAX861IUA+ functionality?
The LV pin on MAX861IUA+ determines topology: grounding LV selects inverter mode (VOUT ≈ –VIN), while connecting LV to OUT selects doubler mode (VOUT ≈ +2VIN). This is not a logic-level enable - it reconfigures internal switch routing. Incorrect LV connection (e.g., leaving it floating in doubler mode) causes undefined behavior and potential output collapse. Always tie LV explicitly to GND or OUT per application.
MAX861IUA+ 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:
- Active
- 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:
- -25°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-uMAX/uSOP
MAX861IUA+ FAQ
1.How can I place an order for MAX861IUA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX861IUA+ 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 MAX861IUA+ reliable?
The price and inventory of MAX861IUA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX861IUA+ is usually 5 days.
3.What payment methods are accepted for MAX861IUA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX861IUA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX861IUA+?
MAX861IUA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX861IUA+ 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 MAX861IUA+?
For technical support, including MAX861IUA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX861IUA+ requirements.
6.How does Aetrix verify that MAX861IUA+ is sourced from the original manufacturer or authorized distributors?
All MAX861IUA+ 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 MAX861IUA+ meets industry standards.
7.What is the process for return or replacement of MAX861IUA+?
All MAX861IUA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX861IUA+, 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 MAX861IUA+ part is unused and in its original packaging.
Return procedure for MAX861IUA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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