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Analog Devices Inc./Maxim Integrated MAX1681ESA+T
- Part No.:
- MAX1681ESA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX1681ESA+T.pdf
- Description:
- IC REG CHRG PUMP INV 125MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,280
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Product details
Overview
MAX1681ESA+T from Maxim Integrated is a frequency-selectable switched-capacitor voltage converter configured as an inverting or doubling charge pump IC, delivering up to 125mA output current with 3.5Ω typical output resistance, 500kHz/1MHz selectable switching frequency, and operation from +2.0V to +5.5V input - used for local negative supplies in op-amp biasing and interface power rails.
For engineers reviewing the MAX1681ESA+T datasheet, MAX1681ESA+T pinout, MAX1681ESA+T application, or MAX1681ESA+T equivalent, key selection criteria include output impedance under load, shutdown current (<1µA), capacitor size trade-offs (1µF support), and SO-8 package compatibility with board-level space constraints.
Technical Context
The MAX1681ESA+T implements a two-phase, non-regulated charge-pump topology with internal MOSFET switches and no inductor requirement. Its FSEL pin selects between 500kHz (FSEL = high) and 1MHz (FSEL = low) operation, directly determining ripple, capacitor sizing, and supply current draw.
It supports dual configuration modes: inverter (LV = GND, OUT = –VIN) and doubler (LV = OUT, OUT = +2VIN), with SHDN enabling CMOS-controlled shutdown that pulls OUT to ground only in inverter mode. Output voltage accuracy depends on load, input voltage, and external capacitor ESR.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 125mA max - enables replacement of inductor-based regulators in space-constrained designs without compromising drive capability. |
| Switching Frequency | 500kHz / 1MHz - allows use of 1µF low-ESR ceramic capacitors, reducing board area vs. legacy 4.7µF solutions. |
| Input Voltage Range | +2.0V to +5.5V - supports direct connection to common logic rails (3.3V, 5V) without pre-regulation. |
| Output Resistance | 3.5Ω typical - results in ≤440mV drop at 125mA load, ensuring stable negative or doubled output under dynamic conditions. |
| Shutdown Current | <1µA - enables ultra-low-power system sleep states without external disconnect circuitry. |
| Efficiency | 90% typical (inverter, VIN = 5V, ILOAD = 10mA) - minimizes thermal impact and extends battery life in portable applications. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and automotive under-hood peripheral power domains. |
Pinout & Package
MAX1681ESA+T is housed in an 8-pin SO (Small Outline) package with standard 1.27mm pitch, JEDEC MS-012AC compliant, and surface-mount compatible.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FSEL | Frequency select input | CMOS logic input: high = 500kHz, low = 1MHz; determines capacitor size, ripple, and quiescent current. |
| IN | Positive supply input | Accepts +2.0V to +5.5V; powers internal oscillator and charge-pump switches; requires local bypass capacitor. |
| CAP+ | Positive charge-pump capacitor terminal | Connects to one plate of flying capacitor (C1); carries bidirectional 2×IOUT AC current during switching. |
| GND | Power ground reference | Return path for IN, CAP+, and internal circuitry; must be low-impedance to minimize noise coupling. |
| CAP− | Negative charge-pump capacitor terminal | Connects to second plate of flying capacitor (C1); forms charge-transfer path with CAP+ and internal switches. |
| LV | Logic voltage reference | Configures topology: connect to GND for inverter, to OUT for doubler; sets internal switch routing. |
| SHDN | Shutdown control input | CMOS input: high = shutdown (OUT pulled to GND in inverter mode); low = active operation. |
| OUT | Output voltage terminal | Delivers –VIN (inverter) or +2VIN (doubler); output impedance dominates voltage regulation under load. |
Key Features
| Feature | Design Value |
|---|---|
| Configurable topology | Single IC supports both inverting (–VIN) and doubling (+2VIN) outputs via LV pin connection - eliminates need for separate part numbers. |
| Low-output-impedance design | 3.5Ω typical output resistance enables 125mA delivery with ≤440mV drop - suitable for driving moderate-current analog circuitry. |
| High-frequency operation | 1MHz option reduces required capacitor size to 1µF - cuts PCB area by >75% vs. 4.7µF solutions and lowers ESR-related losses. |
| Ultra-low shutdown current | <1µA shutdown draw - preserves battery charge in always-on systems and enables fast wake-up without reset delays. |
| SO-8 package compatibility | Industry-standard 8-pin SO footprint - allows drop-in replacement of MAX860/MAX861 and simplifies layout reuse across generations. |
Applications
| Op-Amp Power Supplies | Interface Power Supplies |
|---|---|
Use Scenario: Providing dual-rail ±3.3V or ±5V supplies for rail-to-rail op-amps in data acquisition front-ends. IC Role / Device Role / Timing Role: Inverting charge pump generating clean –VIN from single +3.3V or +5V rail, with minimal external components. Use Value: Eliminates need for discrete inductors and associated EMI filtering, reducing BOM count and board area while maintaining 125mA sink capability. |
Use Scenario: Generating isolated –5V bias for RS-232 transceivers or +10V for LCD segment drivers in handheld devices. IC Role / Device Role / Timing Role: Doubling or inverting charge pump delivering stable output from main system rail without transformer or inductor. Use Value: Enables compact, low-noise interface power with 1µF capacitor support - critical for thin-profile consumer electronics. |
| Local Negative Supplies | MOSFET Bias |
Use Scenario: Creating localized –3V to –5V supplies for analog sensor signal conditioning circuits in industrial PLC modules. IC Role / Device Role / Timing Role: Inverting voltage converter supplying dedicated negative rail to op-amps and ADC references, decoupled from noisy digital domains. Use Value: 3.5Ω output resistance ensures <440mV droop at full 125mA load - maintains precision reference stability under varying sensor excitation currents. |
Use Scenario: Supplying gate bias voltage for high-side N-channel MOSFETs in DC-DC synchronous buck controllers. IC Role / Device Role / Timing Role: Inverting charge pump generating –5V to –10V gate drive relative to source, enabling efficient high-side switching. Use Value: Supports fast transient response due to low output impedance and 1MHz option - improves PWM fidelity and reduces shoot-through risk. |
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 |
|---|---|---|---|
| MAX861ESA+ | 50mA output current, µMAX-8 package, 125kHz/250kHz switching, requires 4.7µF capacitors. | Lower current, smaller footprint - suited for low-power sensor nodes but not 125mA loads. | Select MAX861ESA+ only when board space is critical and load current ≤50mA. |
| ICL7660CPA+ | 10mA output, no frequency select, fixed ~10kHz operation, 55Ω output resistance, DIP-8/SO-8. | Legacy solution with higher dropout and ripple - limited to micropower analog biasing. | Choose ICL7660CPA+ only for cost-sensitive, low-current legacy designs where efficiency and size are secondary. |
Compared with MAX861ESA+ and ICL7660CPA+, the MAX1681ESA+T delivers 2.5× higher output current than MAX861ESA+ and 12.5× more than ICL7660CPA+, while supporting 1µF capacitors and 1MHz operation - making it optimal for modern compact, high-current analog power rails.
Availability
MAX1681ESA+T is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable medical devices, and embedded test equipment requiring stable component supply with extended temperature range support.
Supply support for MAX1681ESA+T 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, communications, and computing markets.
The MAX1680/MAX1681 product line was designed to replace inductor-based DC-DC converters in space- and cost-constrained applications where low-noise, capacitor-only power conversion is required.
FAQ
What is the maximum output current specification for the MAX1681ESA+T?
The MAX1681ESA+T delivers up to 125mA output current in both inverter and doubler configurations, verified across the full operating temperature range (–40°C to +85°C) and input voltage range (+2.0V to +5.5V). This rating assumes proper capacitor selection (1µF low-ESR ceramics), adequate PCB thermal relief, and ambient temperature ≤+70°C per derating curves in the datasheet. The MAX1681ESA+T maintains this current capability with ≤440mV output voltage drop at full load due to its 3.5Ω typical output resistance.
How does the FSEL pin configure switching frequency on the MAX1681ESA+T?
On the MAX1681ESA+T, the FSEL pin is a CMOS-compatible logic input that selects between two fixed switching frequencies: 500kHz when FSEL is driven high (≥2.0V), and 1MHz when FSEL is driven low (≤0.8V). This selection directly impacts external capacitor sizing (1µF sufficient at 1MHz), supply current draw (higher at 1MHz), and output ripple amplitude (lower at 1MHz). The frequency is not adjustable beyond these two points - no analog or resistor-based tuning is supported.
Can the MAX1681ESA+T be used in voltage-doubler mode, and what are the input requirements?
Yes, the MAX1681ESA+T supports voltage-doubler mode by connecting the LV pin to the OUT pin. In this configuration, it delivers +2VIN output with up to 125mA load. The minimum input voltage increases slightly versus inverter mode: ≥+2.5V for reliable operation (vs. +2.0V in inverter mode), and optimal performance occurs at +4.0V to +5.5V input. Output voltage accuracy degrades linearly with load due to fixed 3.5Ω output resistance - e.g., at 125mA and VIN = 5V, expected output is ~9.56V instead of ideal 10V.
What happens to the OUT pin during shutdown on the MAX1681ESA+T?
During shutdown (SHDN = high), the MAX1681ESA+T disables its internal charge-pump switches and pulls the OUT pin to GND - but only in inverter configuration (LV = GND). In doubler mode (LV = OUT), shutdown is not functional per datasheet specification; SHDN must be tied to OUT to maintain operation. The shutdown current drops below 1µA regardless of configuration, and OUT remains at its last active-state voltage unless externally pulled.
Is the MAX1681ESA+T pin-compatible with earlier Maxim charge pumps like the MAX860/MAX861?
No, the MAX1681ESA+T is not pin-compatible with MAX860/MAX861 despite sharing the same 8-pin SO package outline. Pin functions differ: MAX860/MAX861 use pin 7 for OSC (oscillator enable), whereas MAX1681ESA+T uses pin 7 for SHDN (shutdown control); similarly, pin 6 (LV on MAX1681ESA+T) serves as GND on MAX860/MAX861. Direct replacement requires PCB layout revision to accommodate SHDN and LV signal routing - confirmed by Maxim's compatibility note in the datasheet.
MAX1681ESA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Ratiometric
- Output Configuration:
- Positive or Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- -Vin, 2Vin
- Voltage - Output (Max):
- -
- Current - Output:
- 125mA
- Frequency - Switching:
- 500kHz, 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX1681ESA+T FAQ
1.How can I place an order for MAX1681ESA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1681ESA+T 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 MAX1681ESA+T reliable?
The price and inventory of MAX1681ESA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1681ESA+T is usually 5 days.
3.What payment methods are accepted for MAX1681ESA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1681ESA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1681ESA+T?
MAX1681ESA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1681ESA+T 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 MAX1681ESA+T?
For technical support, including MAX1681ESA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1681ESA+T requirements.
6.How does Aetrix verify that MAX1681ESA+T is sourced from the original manufacturer or authorized distributors?
All MAX1681ESA+T 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 MAX1681ESA+T meets industry standards.
7.What is the process for return or replacement of MAX1681ESA+T?
All MAX1681ESA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1681ESA+T, 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 MAX1681ESA+T part is unused and in its original packaging.
Return procedure for MAX1681ESA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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