High-Efficiency, Current-Mode, Inverting PWM Controller

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MAX1846/MAX1847 high-efficiency PWM inverting controllers allow designers to implement compact, low-noise, negative-output DC-DC converters for telecom and networking applications. Both devices operate from +3V to +16.5V input and generate -500mV to -200V output. To minimize switching noise, both devices feature a current-mode, constant-frequency PWM control scheme. The operating frequency can be set from 100kHz to 500kHz through a resistor.

The MAX1846 is available in an ultra-compact 10-pin µMAX® package. Operation at high frequency, compatibility with ceramic capacitors, and inverting topology without transformers allow for a compact design. Compatibility with electrolytic capacitors and flexibility to operate down to 100kHz allow users to minimize the cost of external components. The high-current output drivers are designed to drive a P-channel MOSFET and allow the converter to deliver up to 30W.

The MAX1847 features clock synchronization and shutdown functions. The MAX1847 can also be configured to operate as an inverting flyback controller with an N-channel MOSFET and a transformer to deliver up to 70W. The MAX1847 is available in a 16-pin QSOP package.

Current-mode control simplifies compensation and provides good transient response. Accurate current-mode control and over current protection are achieved through low-side current sensing.
MAX1846, MAX1847: Functional Diagram MAX1846, MAX1847: Functional Diagram Enlarge+

Key Features

  • 90% Efficiency
  • +3.0V to +16.5V Input Range
  • -500mV to -200V Output
  • Drives High-Side P-channel MOSFET
  • 100kHz to 500kHz Switching Frequency
  • Current-Mode, PWM Control
  • Internal Soft-Start
  • Electrolytic or Ceramic Output Capacitor
  • The MAX1847 also offers:
    • Synchronization to External Clock Shutdown
    • N-Channel Inverting Flyback Option


  • Cellular Base Stations
  • CO DSL Line Driver Supplies
  • Industrial Power Supplies
  • Network Equipment
  • Optical Networking Equipment
  • Servers
  • SLIC Supplies
  • VOIP Supplies
Part Number VIN
Output Adjust. Method DC-DC Outputs Oper. Freq.
Switch Type Package/Pins Budgetary
min max min max max See Notes
MAX1846  3 16.5 -2 -200 5 Resistor 1 500 External
$2.65 @1k
$2.94 @1k
See All Inverting Switching Regulators (22)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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