MAQ5280 データシートの表示（PDF） - Micrel

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MAQ5280

25mA, 120V, Low IQ, High PSRR LDO

Micrel 

Micrel, Inc.

Functional Description

MAQ5280 is a high performance linear regulator which

accepts wide input operating range 4.5V to 120V. This

allows the use in harsh environments. The input can

surge from 0V to 120V within a millisecond. The first

stage bypass regulator isolates output from this input by

producing an intermediate head voltage which is a input-

to-post regulator. This post regulator gives the control to

regulate the required output voltage. The output voltage

is adjustable from 1.22V to 5V.

VIN Pin

VIN pin is the supply input pin. A 0.18µF or larger

capacitor with proper voltage rating is recommended for

filtering the input voltage variations and noise on the

input voltage. This capacitor should be close to the VIN

and GND pins.

CBYP Pin

The Bypass pin is the output of the Bypass regulator and

the input of the post regulator. By connecting a capacitor

from the CBYP pin-to-GND, a greater stability and a much

higher PSRR is achieved. A 10µF ceramic capacitor is

recommended and this significantly decreases VOUT

noise and perturbations due to line transients. When the

MAQ5280 is enabled, the Bypass pin voltage is

regulated at 5.5V. To maintain 5.5V regulation and high

PSRR, the VIN must be no lower than 6.5V. For VIN less

than 6.5V while in dropout, the PSRR is reduced.

MAQ5280

EN Pin

EN pin is a logic level enable input which turns

MAQ5280 on/off. Drive EN pin level high to turn the

device ON and drive EN pin low to keep the device in

shutdown mode. In shutdown mode the MAQ5280 draws

typically 20nA from the input supply. EN pin can

withstand 120V, allowing EN always connected to input

supply for always-ON operation.

ADJ Pin

ADJ pin gives the flexibility to set the output voltage to

the requirement from 1.22V to 5V. Use a resistor divider

from output and connect to ADJ pin, internal reference is

typically 1.219V.

GND Pin

This GND pin provides the ground for all the electrical

connections. MAQ5280 has exposed pad underneath

the package which should be connected to ground. If

this exposed pad is connected to wide ground plane it

would improve the thermal performance of MAQ5280.

NC Pins

There are two NC pins on the package which are not

connected internally.

VOUT Pin

The VOUT pin is the regulated output of the post

regulator. When the MAQ5280 is enabled, VOUT

regulates at a fixed voltage, when disabled, VOUT is high

impedance. A 2.2µF or larger ceramic capacitor must be

connected to VOUT pin-to-ground.

October 2008

9

M9999-102708-B

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