3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

8

_______________________________________________________________________________________

MAX710

SHDN

LX

STBY

N/E

LBO

LBI+

LBI-

REF

PGND

0.1

µF

GND

ILIM

PS

OUT

4.7

µF

100

µF

100

µF

L1

3/5

MAX710

SHDN

LX

STBY

N/E

LBO

R5 = R6

R5 = R6 (4.08)

LBI+

LBI-

REF

PGND

0.1

µF

GND

ILIM

PS

OUT

R6

R5

4.7

µF

100

µF

100

µF

L1

3/5

Figure 2a. High-Efficiency Operating Configuration for

Figure 2b. High-Efficiency Operating Configuration for

input voltage is limited to 7V. This voltage limitation is

easily overcome, however, by configuring the LBO out-

put to change modes based on input voltage, allowing

an 11V maximum input with high-efficiency configura-

tions. Four operating configurations are described in

Table 1 and in the following subsections.

With N/E connected to GND, when the IC boosts, the

linear regulator operates only as a switch, with mini-

lation begins). This configuration is limited to no more

than 7V input, but provides best efficiency for battery-

only operation or low-voltage AC adapter usage.

In this configuration, N/E is driven high by LBO when

boosts, and the linear regulator operates as a switch,

efficiency is poorer than in configuration 1, so configu-

ration 2 is most suitable when the battery voltage is less

Up to 11V

2

Up to 11V

4

Up to 11V

3

High efficiency,

(Figure 2a)

Low noise

High efficiency,

(Figure 2b)

DESCRIPTION

High efficiency,

INPUT

VOLTAGE

Up to 7V

1

NO.

LBO = N/E

N/E = PS

LBO = N/E

LBI- = REF

LBI+ = R5, R6

CONNECTIONS

N/E = GND

Table 1. Operating Configurations