1. Products
  2. Power Management
  3. Switching Regulators
  4. Step-Down (Buck) Regulators
  5. Internal Power Switch Buck Regulators
  6. MAX1685


Features and Benefits

  • Up to 96% Efficiency
  • 1A Guaranteed Output Current
  • 100% Duty Cycle in Dropout
  • 2.7V to 14V Input Range (15V Absolute Max)
  • ±1% Accurate Reference Output
  • 0.24Ω P-Channel On-Resistance
  • Synchronizable Switching Frequency
  • Fixed-Frequency PWM Operation
    • 300kHz (MAX1684)
    • 600kHz (MAX1685)
  • 150µA Normal-Mode Quiescent Current
  • 25µA Low-Power Mode Quiescent Current
  • 2µA Shutdown Current
  • Dual Mode™ Fixed 3.3V (±1%) Output or Adjustable Output (1.25V to VIN)
  • Small 16-QSOP Package
  • Auxiliary Output (CVL): 3V/5mA

Product Details

The MAX1684/MAX1685 are high-efficiency, internal-switch, pulse-width modulation (PWM) step-down switching regulators intended to power cellular phones, communicating PDAs, and handy-terminals. These devices deliver a guaranteed 1A output current from two lithium-ion (Li+) batteries. Their wide-input voltage range of 2.7V to 14V gives design flexibility and allows batteries to charge from a wall cube, since the ICs operate at the higher voltages that occur when the battery is removed. The output voltage is preset to 3.3V or can be externally adjusted from 1.25V to VIN.

The low on-resistance power switch and built-in synchronous rectifier provide high efficiencies of up to 96%. There are four modes of operation: fixed-frequency, normal, low-power, and shutdown. The fixed-frequency PWM mode of operation offers excellent noise characteristics. The normal mode maintains high efficiency at all loads. The low-power mode is used to conserve power in standby or when full load is not required. The shutdown mode is used to power down the device for minimal current draw.

The MAX1684 runs at 300kHz for applications that require highest efficiency. The MAX1685 runs at 600kHz to allow the use of smaller external components. These devices can also be synchronized to an external clock. Other features include a 100% duty cycle for low-dropout applications, an auxiliary 3V/5mA output, and a 1% accurate reference.

Both devices are available in a space-saving 16-QSOP package. An evaluation kit is also available to help speed designs. For a similar device in a 10-pin µMAX® package with lower input voltage requirements (5.5V max), refer to the MAX1692 data sheet.


  • Cell Phones
  • Computer Peripherals
  • PDAs and Handy-Terminals
  • Personal Communicators
  • Two-Way Radios and Walkie-Talkies

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

Product Recommendations

MAX1685 Companion Parts

Recommended Related Parts

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
MAX1685EEE+ Material Declaration Reliability Data 16-QSOP-150_MIL
MAX1685EEE+T Material Declaration Reliability Data 16-QSOP-150_MIL
Wafer Fabrication Data MAX1685 Reliability Data

Sample & Buy

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Buy Now Pricing

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List Pricing

(*)The 1Ku list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


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