Low-Cost Voltage-Mode PWM

Step-Down Controllers

6

_______________________________________________________________________________________

L = 22

µF

Typical Operating Characteristics (continued)

1A/div

1V/div

2V/div

INDUCTOR

CURRENT

VOUT

VIN

10ms/div

SHUTDOWN WAVEFORMS

NO LOAD

Pin Description

PIN

MAX1966

MAX1967

NAME

FUNCTION

1

10

BST

Positive Supply of DH Driver. Connect 0.1µF ceramic capacitor between BST and LX.

2

1

COMP/EN

Compensation Pin. Pulling COMP/EN low with an open-collector or open-drain device

turns off the output.

3

2

FB

—

3

VCC

Internal Chip Supply. Connect to VL via a 10

Ω resistor.

4

4

VIN

Power Supply for LDO Regulator in the MAX1967 and Chip Supply for the MAX1966.

Bypass with a ceramic capacitor to ground (see application circuit).

—

5VL

Output of Internal 5V LDO. Bypass with a 2.2µF capacitor to GND, or if VIN < 5.5,

connect VL to VIN and bypass with a 0.1µF capacitor to GND.

5

6

DL

6

7

GND

Ground and Negative Current-Sense Input

78

LX

8

9

DH