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1-Cell-to-3-Cell, High-Power, Low-Noise, Step-Up DC-DC Converters

Integrated 2-Channel ADC Allows Accurate Battery Voltage Monitoring

Product Details

Key Features

Applications/Uses

Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 0.7
VIN (V) (max) 5.5
VOUT1 (V) (min) 2.7
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 0.3
Switch Type Internal
Preset VOUT (V) 3.3
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
ICC (mA) (typ) 0.035
Shutdown Mode Supply Current (µA) (typ) 4
Shutdown Mode Supply Current (µA) (max) 20
# DC-DC Outputs 1
Switching Frequency (kHz) 400
Package/Pins SOIC (N)/16
Budgetary
Price (See Notes)
2.5
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 0.7
VIN (V) (max) 5.5
VOUT1 (V) (min) 2.7
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 0.3
Switch Type Internal
Preset VOUT (V) 3.3
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
ICC (mA) (typ) 0.035
Shutdown Mode Supply Current (µA) (typ) 4
Shutdown Mode Supply Current (µA) (max) 20
# DC-DC Outputs 1
Switching Frequency (kHz) 400
Package/Pins SOIC (N)/16
Budgetary
Price (See Notes)
2.5

Key Features

  • Up to 95% Efficiency
  • 3.3V Dual Mode™ or 2.7V to 5.5V Adj. Output
  • 0.7V to 5.5V Input Range
  • 0.15mW Standby Mode
  • 300kHz PWM Mode or Synchronizable
  • Two-Channel ADC with Serial Output
  • Power-Good Function

Applications/Uses

  • Cell Phones
  • Digital Cordless Phones
  • Handheld Instruments (PDAs, Palmtops)
  • Local 3.3V to 5V Supplies
  • Palmtop Computers
  • PCS Phones
  • Personal Communicators

Description

The MAX848/MAX849 boost converters set a new standard of high efficiency and high integration for noise-sensitive power-supply applications, such as portable phones and small systems with RF data links. The heart of the these devices is a synchronous boost-topology regulator that generates a fixed 3.3V output (or 2.7V to 5.5V adjustable output) from one to three NiCd/NiMH cells or one Li-Ion cell.

Synchronous rectification provides a 5% efficiency improvement over similar nonsynchronous boost regulators. In standby mode, pulse-skipping PFM operation keeps the output voltage alive with only 150µW quiescent power consumption. Fixed-frequency PWM operation ensures that the switching noise spectrum is limited to the 300kHz fundamental and its harmonics, allowing easy post-filtering noise reduction. For even tighter noise spectrum control, synchronize to a 200kHz to 400kHz external clock.

Battery monitoring is provided by a two-channel, voltage-to-frequency analog-to-digital converter (ADC). One channel is intended for a single-cell battery input (0.625V to 1.875V range), while the other channel is for monitoring higher voltages (0V to 2.5V range).

Two control inputs are provided for push-on, push-off control via a momentary pushbutton switch. Upon power-up, an internal comparator monitors the output voltage to generate a power-good output (POK).

The devices differ only in the current limit of the N-channel MOSFET power switch: 0.8A for the MAX848, and 1.4A for the MAX849.

Simplified Block Diagram

MAX848, MAX849: Typical Operating Circuit MAX848, MAX849: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .