Detailed Description

The MAX8902A/MAX8902B low-noise, low-dropout lin-

ear regulators deliver up to 500mA of output current

width. These regulators maintain their output voltage

over a wide input range, requiring only 100mV of input-

to-output headroom at full load.

The MAX8902 maintains a low 80µA typical supply cur-

rent, independent of the load current and dropout volt-

age. The regulator control circuitry includes a

programmable soft-start circuit and short circuit,

reverse current, and thermal-overload protection. Other

features include an enable input and a power-OK

(POK) output (MAX8902B only). A simplified functional

diagram is shown in Figure 1.

The MAX8902A output voltage can be set to 1.5V, 1.8V,

2.0V, 2.5V, 3.0V, 3.1V, 3.3V, 4.6V, or 4.7V using the

SELA and SELB inputs. The MAX8902B output voltage

can be set between 0.6V and 5.3V with an external

resistor voltage-divider.

Enable (EN)

The MAX8902A/MAX8902B include an enable input,

EN. Pull EN low to shut down the output, or drive EN

high to enable the output. If shutdown is not needed,

connect EN to IN.

Low-Noise 500mA LDO Regulators

in a 2mm x 2mm TDFN Package

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5

Pin Description

NAME

PIN

MAX8902A

MAX8902B

FUNCTION

1IN

IN

Regulator Power Input. Connect IN to a supply from 1.7V to 5.5V. Bypass IN with a 10µF

ceramic capacitor to GND.

2

GND

GND

Ground

3EN

EN

Enable Input. A logic-low drives the output low through a 3k

Ω resistor and reduces the

supply current to less than 1µA. Drive logic-high or connect to IN for normal operation.

SELA

—

Output Voltage Select Input. Connect SELA to GND, IN, or leave unconnected. The states of

SELA and SELB are sampled when the regulator turns on and the output voltage is set as

shown in Table 2.

4

—

GS

Internally Used. Connect GS to GND.

SELB

—

Output Voltage Select Input. Connect SELB to GND, IN, or leave unconnected. The states of

SELA and SELB are sampled when the regulator turns on and the output voltage is set as

shown in Table 2.

5

—

POK

Power-OK Output. Open-drain output that goes low when the output is above 91% of the

nominal regulation voltage. POK is high impedance in shutdown or when the output is below

the regulation voltage.

OUTS

—

Output Sense Input. Connect OUTS to the load at a point where accurate regulation is

required, or connect OUTS directly to OUT.

6

—FB

Feedback Input. Connect FB to the center of a resistor voltage-divider connected between

7

BYP

BYP

output noise. Adjust the value of this capacitor to control the output slew rate during startup.

8

OUT

OUT

Regulator Output. Sources up to 500mA at the output regulation voltage. Bypass with a 10µF

(< 0.03

Ω ESR) capacitor to GND.

—

EP

EP

Exposed Paddle. Connect the exposed paddle to a ground plane to provide heat sinking.