Dual 180° Out-of-Phase Buck Controllers with

Sequencing/Prebias Startup and POR

10

______________________________________________________________________________________

O

N

M

DH_

DL_

MAX1875A/MAX1876A POWER-ON-OFF SEQUENCING DEFINITIONS

SYMBOL

DEFINITION

SS_

VOUT_

EN

UVLO

A

B

C

D

E

F

G

HI

J

K

L

Undervoltage lockout trip level is provided in the Electrical Characteristics table.

Internal 5V Linear-Regulator Output

Active-High Enable Input

Output Voltage

Internal Soft-Start Input Signal into Error Amplifier

High-Side Gate-Driver Output

Low-Side Gate-Driver Output

EN is pulled high.

Normal operation

Resumes normal operation

EN is pulled low.

EN is pulled high.

Resumes normal operation

Resumes normal operation

UVLO is activated and DL_ is latched low.

Exiting UVLO: DL_ remains latched low until the first fall of DH_ is detected.

DL_ is low after EN is pulled low.

UVLO

VL

EN

VOUT_

SS_

DH_

DL_

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

Figure 3. MAX1875A/MAX1876A Detailed Power-On-Off Sequencing