5V, Step-Down,

Current-Mode PWM DC-DC Converters

6

_______________________________________________________________________________________

MAX738A/MAX744A

SWITCHING WAVEFORMS,

CONTINUOUS CONDITION

2

µs/div

A: SWITCH VOLTAGE (LX PIN), 5V/div, 0V TO +12V

B: INDUCTOR CURRENT, 200mA/div

C: OUTPUT VOLTAGE RIPPLE, 50mV/div, AC-COUPLED

COUT = 390µF,

V+ = 12V, IOUT = 150µA,

MAX738A/MAX744A

SWITCHING WAVEFORMS,

DISCONTINUOUS CONDITION

2

µs/div

A: SWITCH VOLTAGE (LX PIN), 5V/div, 0V TO +12V

B: INDUCTOR CURRENT, 200mA/div

C: OUTPUT VOLTAGE RIPPLE, 50mV/div, AC-COUPLED

COUT = 390µF,

V+ = 12V, IOUT = 150µA

12V

0V

200mA

0mA

A

B

C

0V

200mA

0mA

A

B

C

MAX730A LINE-TRANSIENT RESPONSE

100ms/div

A: VOUT, 50mV/div, DC-COUPLED

B: V+, 5V/div, 6.0V TO 11.0V

IOUT = 300mA

MAX738A/MAX744A LINE-TRANSIENT RESPONSE

100ms/div

A: VOUT, 50mV/div, DC-COUPLED

B: V+, 5V/div, 10.2V TO 16.0V

IOUT = 750mA

11V

6V

0V

A

B

16V

10.2V

A

B

____________________________Typical Operating Characteristics (continued)

12V

0V