MAX8860 データシートの表示（PDF） - Maxim Integrated

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MAX8860

Low-Dropout, 300mA Linear Regulator in µMAX

Maxim Integrated 

Low-Dropout, 300mA

Linear Regulator in µMAX

IN

REVERSE

BATTERY

SHDN PROTECTION

CC

MAX8860

GND

SHUTDOWN

LOGIC

THERMAL

SENSOR

ERROR

AMP

MOS DRIVER

WITH ILIMIT

1.25V

REF

FAULT

DETECT

DUAL-MODE

COMPARATOR

60mV

P

OUT

SET

FAULT

Figure 1. Functional Diagram

Internal P-Channel Pass Transistor

The MAX8860 features a 0.5Ω typical P-channel

MOSFET pass transistor. This provides several advan-

tages over similar designs using PNP pass transistors,

including longer battery life. PNP-based regulators

waste considerable amounts of current in dropout when

the pass transistor saturates. They also use high base-

drive currents under large loads. The P-channel

MOSFET requires no base-drive current, which reduces

quiescent current considerably. The MAX8860 con-

sumes less than 165µA of quiescent current whether in

dropout, light-load, or heavy-load applications (see the

Typical Operating Characteristics).

Output Voltage Selection

The MAX8860 features Dual Mode operation: it operates

in either a preset voltage mode or an adjustable mode.

In preset voltage mode, internal, trimmed feedback

resistors set the output voltage to an adjustable 1.25V to

6.5V output voltage or a fixed-voltage output of 1.8V

(MAX8860EUA18), 2.5V (MAX8860EUA25), 2.77V

(MAX8860EUA27), 2.82V (MAX8860EUA28), 3V

(MAX8860EUA30), or 3.3V (MAX8860EUA33). Select

this mode by connecting SET to ground. In adjustable

mode, select an output between 1.25V and 6.5V using

two external resistors connected as a voltage divider to

SET (Figure 2). Calculate the output voltage with the fol-

lowing equation:

IN

OUT

BATTERY

CIN

2.2µF

33nF

MAX8860

SHDN

SET

CC

FAULT

GND

OUTPUT

VOLTAGE

R1

COUT

2.2µF

100kΩ

R2

Figure 2. Adjustable Output Using External Feedback

Resistors

VOUT

=

VSET

1

+

R1

R2 

where VSET = 1.25V. To simplify resistor selection, use

the following equation:

R1

=

R2





VOUT



− 1

 VSET 

6 _______________________________________________________________________________________

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