High-Efficiency Step-Up Converters with

Reverse Battery Protection

6

_______________________________________________________________________________________

10

µH

GND

RST

+1.5V TO +3.3V

OUT

OUTPUT

+3.3V

POWER-ON

RESET

BATT

BATTERY

SHDN

LX

MAX1833

MAX1835

100k

Ω

10

µF

R4

220k

Ω

R3

1M

Ω

C1

10nF

10

µF

10

µH

GND

FB

+1.5V TO +5.0V

OUT

OUTPUT

+5.0V

BATT

BATTERY

SHDN

LX

MAX1832

MAX1834

R2

309k

Ω

R1

100k

Ω

R3

1M

Ω

R4

220k

Ω

C1

10nF

10

µF

Pin Description

PIN

MAX1832

MAX1834

MAX1833

MAX1835

NAME

FUNCTION

11

SHDN

Shutdown. A high logic level turns on the device. When SHDN is low the part is off,

and the current into BATT is typically 0.1µA. For the MAX1832/MAX1833, the

battery is connected to OUT through an internal PFET and the external inductor

when SHDN is low. SHDN can be used for low-battery cutoff (1.228V threshold).

See Low-Battery Cutoff. SHDN has reverse battery protection.

2

2

BATT

Battery Voltage Connection. BATT has reverse battery protection.

3

3

GND

Ground

44

LX

Inductor Connection. N-channel MOSFET switch drain and synchronous

rectifier P-channel switch drain. LX has reverse battery protection.

5

5

OUT

Output Voltage. Bootstrapped supply for the device. Output sense point for

MAX1833/MAX1835.

6

—

FB

MAX1832/MAX1834 Feedback Input. Set the output voltage through a

resistor-divider network. See Setting the Output Voltage.

—

6

RST

MAX1833/MAX1835 Power-On Reset Open-Drain Output. RST pulls low when

the output is 10% below the regulation point. If not used, connect to GND.

Figure 1a. MAX1833/MAX1835 Typical Operating Circuit

Figure 1b. MAX1832/MAX1834 Typical Operating Circuit