MAX856

3.3V/5V or Adjustable Output, Step-Up DC-DC Converters


Description

The MAX856-MAX859 are high-efficiency, CMOS, step-up, DC-DC switching regulators for small, low input voltage or battery-powered systems. The MAX856/MAX858 accept a positive input voltage between 0.8V and VOUT and convert it to a higher, pin-selectable output voltage of 3.3V or 5V. The MAX857/MAX859 adjustable versions accept 0.8V to 6.0V input voltages and generate higher adjustable output voltages in the 2.7V to 6.0V range. Typical efficiencies are greater than 85%. Typical quiescent supply current is 25µA (1µA in shutdown).

The MAX856-MAX859 combine ultra-low quiescent supply current and high efficiency to give maximum battery life. An internal MOSFET power transistor permits high switching frequencies. This benefit, combined with internally set peak inductor current limits, permits the use of small, low-cost inductors. The MAX856/MAX857 have a 500mA peak inductor current limit. The MAX858/MAX859 have a 125mA peak inductor current limit.
MAX856, MAX857, MAX858, MAX859: Typical Operating Circuit MAX856, MAX857, MAX858, MAX859: Typical Operating Circuit Enlarge+

Key Features

  • 0.8V to 6.0V Input Supply Voltage
  • 0.8V Typ Start-Up Supply Voltage
  • 85% Efficiency at 100mA
  • 25µA Quiescent Current
  • 1µA Shutdown Mode
  • 125mA and 500mA Switch-Current Limits Permit Use of Low-Cost Inductors
  • Up to 500kHz Switching Frequency
  • ±1.5% Reference Tolerance Over Temperature
  • Low-Battery Detector (LBI/LBO)
  • 8-Pin SO and µMax Packages

Applications/Uses

  • 2-Cell and 3-Cell Battery-Operated Equipment
  • 3.3V to 5V Step-Up Conversion
  • Glucose Meters
  • Medical Instrumentation
  • Palmtop Computers
  • Personal Data Communicators/Computers
  • Portable Data-Collection Equipment
Part Number VIN
(V)
VIN
(V)
VOUT1
(V)
VOUT1
(V)
Preset VOUT
(V)
IOUT1
(A)
Output Adjust. Method Switch Type Power Good Signal ICC
(mA)
Shutdown Mode Supply Current
(µA)
Shutdown Mode Supply Current
(µA)
DC-DC Outputs Oper. Freq.
(kHz)
Package/Pins Budgetary
Price
min max min max max typ typ max See Notes
MAX856  0.8 6 3.3 5
3.3
5
0.15 Preset Internal Yes 0.025 1 5 1 500
µMAX/8
PDIP(N)/8
SOIC(N)/8
$2.30 @1k
MAX857  2.7 6 - 0.15 Resistor
µMAX/8
PDIP(N)/8
SOIC(N)/8
$2.30 @1k
MAX858  3.3 5
3.3
5
0.06 Preset
µMAX/8
PDIP(N)/8
SOIC(N)/8
$2.30 @1k
MAX859  2.7 6 - 0.06 Resistor
µMAX/8
PDIP(N)/8
SOIC(N)/8
$2.38 @1k
See All Step-Up Switching Regulators (94)
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.


MAX856EVKIT: Evaluation Kit for the MAX856

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