500mA, Low-Voltage Linear Regulator in µMAX

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9

response graphs (see Typical Operating Characteris-

tics) show two components of the output response: a

DC shift from the output impedance due to the load

current change, and the transient response. A typical

transient overshoot for a step change in the load cur-

rent from 5mA to 500mA is 40mV. Increasing the output

capacitor’s value and decreasing the ESR attenuates

the overshoot.

Input-Output (Dropout) Voltage

A regulator’s minimum input-to-output voltage differen-

tial (dropout voltage) determines the lowest usable sup-

ply voltage. In battery-powered systems, this

determines the useful end-of-life battery voltage.

Because the MAX1806 uses a P-channel MOSFET pass

transistor, its dropout voltage is a function of drain-to-

current (see Typical Operating Characteristics):

Chip Information

TRANSISTOR COUNT: 949

OUT

OUT

SET

GND

IN

IN

SHDN

POK

10

µF

1

µF

ON

OFF

R1 = R2

- 1

0.8V

MAX1806

+2.25V TO +5.5V

Figure 2. Adjustable Output Using External Feedback Resistors

Figure 3. Power Operating Regions: Maximum Output Current

vs. Supply Voltage

0

0.2

0.1

0.3

0.6

0.7

0.5

0.4

0.8

0

1.0 1.5 2.0 2.5

0.5

3.0 3.5 4.0 4.5 5.0

INPUT-OUTPUT VOLTAGE DIFFERENTIAL (V)

POWER-

µMAX PACKAGE OPERATING

°C

°C

°C

°C

CONTINUOUS CURRENT LIMIT