5V, Step-Down,

Current-Mode PWM DC-DC Converters

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7

NAME

FUNCTION

1

SHDN

Shutdown—active low. Ground to power-down chip, tie to V+ for normal operation.

Output voltage falls to 0V when

SHDN is low.

2

REF

3

SS

Soft-Start. Capacitor between SS and GND provides soft-start and short-circuit protection.

510k

Ω resistor from SS to SHDN provides current boost.

2

3

4

CC

Compensation Capacitor Input externally compensates the outer feedback loop.

Connect to OUT with a 330pF capacitor.

5

OUT

Output Voltage Sense Input provides regulation feedback sensing. Connect to +5V output.

6

GND

Ground pins are internally connected. Connect both pins to ground.

7

LX

Drain of internal P-channel power MOSFET.

7

8

9

8

V+

Supply-Voltage Input. Bypass to GND with 1µF ceramic and large-value electrolytic capaci-

tors in parallel. The 1µF capacitor must be as close to V+ and GND pins as possible.

N.C.

No Connect—no internal connections to these pins.

10, 11

12, 13, 14

1, 15, 16

4, 5, 6

______________________________________________________________Pin Description

MAX730A

LOAD-TRANSIENT RESPONSE

50ms/div

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

B: IOUT, 200mA/div, 20mA TO 300mA

V+ = 9V

MAX738A/MAX744A

LOAD-TRANSIENT RESPONSE

50ms/div

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

B: IOUT, 500mA/div, 50mA TO 750mA

V+ = 12V

300mA

20mA

A

B

____________________________Typical Operating Characteristics (continued)

16-PIN

WIDE SO

8-PIN

DIP/SO

Reference-Voltage Output (+1.23V) supplies up to 100µA for extended loads.

Bypass to GND with a capacitor that does not exceed 0.047µF.

750mA

50mA

A

B

PIN