5V/3.3V/3V/Adjustable-Output,

Step-Up/Step-Down DC-DC Converters

_______________________________________________________________________________________

5

A: SWITCH VOLTAGE (LX PIN), 2V/div

B: INDUCTOR CURRENT, 0.5A/div

C: OUTPUT VOLTAGE RIPPLE, 50mV/div

SWITCHING WAVEFORMS—

CONTINUOUS CONDUCTION

A

B

C

0mA

5

µs/div

A: SWITCH VOLTAGE (LX PIN), 2V/div

B: INDUCTOR CURRENT, 0.5A/div

C: OUTPUT VOLTAGE RIPPLE, 50mV/div

SWITCHING WAVEFORMS—

DISCONTINUOUS CONDUCTION

A

B

C

2

µs/div

0mA

A: SWITCH VOLTAGE (LX PIN), 2V/div

B: INDUCTOR CURRENT, 0.5A/div

C: OUTPUT VOLTAGE RIPPLE, 50mV/div

STEP-DOWN CONVERSION

A

B

C

5

µs/div

0mA

A: SHDN, 2V/div

MAX878

START-UP TIME

GND

GND

10ms/div

A

B

A: INPUT VOLTAGE, 2V/div, 2V to 6V

B: OUTPUT VOLTAGE, 50mV/div

STEP-UP/STEP-DOWN

OPERATION

A

B

20ms/div

GND

____________________________Typical Operating Characteristics (continued)