MAX1971

Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-Down Regulator with POR and RSI/PFO

Smallest Internal Switch Dual Step-down for GBICs , xDSL Modems & USB Powered Devices


Please check latest availability status for a specific part variant.

Description

The MAX1970/MAX1971/MAX1972 dual-output current-mode PWM buck regulators operate from 2.6V to 5.5V input and deliver a minimum of 750mA on each output. The MAX1970 and MAX1972 operate at a fixed 1.4MHz (MAX1971 operates at 700kHz) to reduce output inductor and capacitor size and cost. Switching the regulators 180° out-of-phase also reduces the input capacitor size and cost. Ceramic capacitors can be used for input and output.

The output voltages are programmable from 1.2V to VIN using external feedback resistors, or can be preset to 1.8V or 3.3V for output 1 and 1.5V or 2.5V for output 2. When one output is higher than 1.2V, the second can be configured down to sub-1V levels. Output accuracy is better than ±1% over variations in load, line, and temperature. Internal soft-start reduces inrush current during startup.

All devices feature power-on reset (active-low POR). The MAX1971 includes a reset input (RSI), which forces active-low POR low for 175ms after RSI goes low. The MAX1970 and MAX1972 include an open-drain power-fail output (PFO) that monitors input voltage and goes high when the input falls below 3.94V. For USB-powered xDSL modems, this output can be used to detect USB power failure. A minimum switching frequency of 1.2MHz ensures operation outside the xDSL band.

Learn More About PowerMind™
MAX1970, MAX1971, MAX1972: Typical Operating Circuit MAX1970, MAX1971, MAX1972: Typical Operating Circuit Enlarge+

Key Features

  • Current-Mode, 1.4MHz Fixed-Frequency PWM Operation
  • 180° Out-of-Phase Operation Reduces Input Capacitor
  • ±1% Output Accuracy Over Load, Line, and Temperature Ranges
  • 750mA Guaranteed Output Current
  • 2.6V to 5.5V Input
  • Power-On Reset Delay of 16.6ms (MAX1970) or 175ms (MAX1971 and MAX1972)
  • Power-Fail Output (MAX1970 and MAX1972 Only)
  • Power-On Reset Input (MAX1971 Only)
  • Operation Outside xDSL Band
  • Ultra-Compact Design with Smallest External Components
  • Outputs Adjustable from 0.8V to VIN or 1.8V/3.3V and 1.5V/2.5V Preset
  • All-Ceramic Capacitor Application
  • Soft-Start Reduces Inrush Current

Applications/Uses

  • Copper Gigabit SFP and GBIC Modules
  • Dual LDO Replacement
  • USB-Powered Devices
  • XDSL Modems
  • xDSL Routers

See parametric specs for Step-Down Switching Regulators (408)


Part NumberVIN
(V)
VIN
(V)
VOUT1
(V)
VOUT1
(V)
Preset VOUT
(V)
Output Adjust. MethodIOUT1
(A)
Switch TypeSynchronous SwitchingPower Good SignalDC-DC OutputsOper. Freq.
(kHz)
Package/PinsBudgetary
Price
minmaxminmaxmaxSee Notes
MAX1970 2.65.50.85
1.5
1.8
2.5
3.3
Preset
Resistor
0.75InternalYesYes21400
QSOP/16
$7.47 @1k
MAX1971 700
QSOP/16
$7.47 @1k
MAX1972 1400
QSOP/16
$3.74 @1k

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.

MAX1972EVKIT: Evaluation Kit for the MAX1970, MAX1971, MAX1972
Product Reliability Reports: MAX1971.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

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.

Quality Management System >
Environmental Management System >

 
Status:
Package:
Temperature:

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