The MAX877/MAX878/MAX879 are pulse-skipping, stepup/ step-down DC-DC converters that provide a regulated output from inputs both above and below the output. They require only three external components-an inductor (typically 22H) and two filter capacitors.
The MAX877 delivers a regulated 5V output from 2.5V to 6.2V inputs. The MAX878 generates pin-selectable voltages of 3.0V or 3.3V from 1.5V to 6.2V inputs. The MAX879 output can be adjusted from 2.5V to 6V via an external resistor divider from 2.5V to 6.2V inputs.
A unique high-power, internal, synchronous rectifier design (Active Rectifier™) enables the devices to regulate in a switched linear mode if the input voltage is higher than the desired output voltage. When the input voltage falls below the output voltage, the MAX877/MAX878/MAX879 will smoothly switch into a pulse-skipping boost mode and step up from input voltages as low as 1V. In shutdown, the active rectifier disconnects the output from the source. This stops the current drain from input to output associated with conventional step-up converters.
High-frequency operation (up to 300kHz) allows the use of small surface-mount inductors. Supply current is 195A under no load, and only 20A in shutdown mode. For 1-cell (1V) step-up converters with similar performance and the
same pinout, refer to the MAX777/MAX778/MAX779 data sheet.
Supply Voltage (IN to PGND) ...................................0V to +7V
Output Short-Circuit Duration to PGND, AGND (Note 1)..30sec
Voltage Applied to
LX (switch off)......................................................-0.3V to +7V
(switch on) .......................................30sec short to IN or OUT
OUT, SHDN...........................................................-0.3V to +7V
FB ..........................................................-0.3V to (OUT + 0.3V)
AGND to PGND......................................................-0.3V, +0.3V
Reverse Battery Current................................................900mA
Continuous Power Dissipation (TA = +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) ...........727mW
SO (derate 5.88mW/°C above +70°C)........................471mW
CERDIP (derate 8.00mW/°C above +70°C).................640mW
Operating Temperature Ranges:
MAX87_C_A........................................................0°C to +70°C
MAX87_E_A ....................................................-40°C to +85°C
MAX87_MJA ..................................................-55°C to +125°C
Storage Temperature Range ........................-65°C to +150°C
Lead Temperature (soldering, 10sec) ..........................+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Note 1: The output may be shorted to ground continuously if the package power dissipation is not exceeded.
Post a Buying Lead
Required Field 
