MAX882MJA Просмотр технического описания (PDF) - Maxim Integrated

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MAX882MJA

5V/3.3V or Adjustable, Low-Dropout, Low IQ, 200mA Linear Regulators

Maxim Integrated 

5V/3.3V or Adjustable, Low-Dropout,

Low IQ, 200mA Linear Regulators

IN

LBI

LBO

N

LOW-BATTERY

COMPARATOR

ERROR AMP

MOSFET DRIVER

WITH FOLDBACK

CURRENT LIMIT

REVERSE-

P

CURRENT

PROTECTION

OFF

(STBY)

SHUT-

DOWN

LOGIC

1.20V

REFERENCE

THERMAL

SENSOR

GND

( ) ARE FOR MAX882

Figure 1. MAX882/MAX883/MAX884 Functional Diagram

DUAL-MODE

COMPARATOR

OUT

SET

R1

R2

65mV

In adjustable mode, the user selects an output voltage

in the 1.25V to 11V range by connecting two external

resistors, used as a voltage divider, to the SET pin

(Figure 2).

The output voltage is set by the following equation:

VOUT = VSET 1 +

R1

R2 

where VSET = 1.20V.

To simplify resistor selection:

R1

=

R2





VOUT

VSET

−



1

Since the input bias current at SET is nominally zero,

large resistance values can be used for R1 and R2 to

minimize power consumption without losing accuracy.

Up to 1.5MΩ is acceptable for R2. Since the VSET toler-

ance is less than ±40mV, the output can be set using

fixed resistors instead of trim pots.

Standby Mode (MAX882)

The MAX882 has a standby feature that disconnects

the input from the output when STBY is brought low, but

keeps all other circuitry awake. In this mode, VOUT

drops to 0V, and the internal biasing circuitry (including

the low-battery comparator) remains on. The maximum

quiescent current during standby is 15µA. STBY is a

comparator input with the other input internally tied to

the reference voltage. Use a resistor network as shown

in Figure 3 to set a standby-mode threshold voltage for

undervoltage lockout. Connect STBY to IN for normal

operation.

OFF Mode (MAX883/MAX884)

A low-logic input on the OFF pin shuts down the

MAX883/MAX884. In this mode, the pass transistor,

control circuit, reference, and all biases are turned off,

and the supply current is reduced to less than 1µA.

LBO is undefined in OFF mode. Connect OFF to IN for

normal operation.

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