Current Limit

The MAX8875 includes a current limiter that monitors

and controls the pass transistor’s gate voltage, limiting

the output current to 390mA (typ). For design purpos-

es, consider the current limit to be 160mA min to

600mA max. The output can be shorted to ground for

an indefinite period of time without damaging the part.

Thermal-Overload Protection

the thermal sensor signals the shutdown logic, turning

off the pass transistor and allowing the IC to cool. The

thermal sensor will turn the pass transistor on again after

the IC’s junction temperature cools by 20°C, resulting in

a pulsed output during continuous thermal-overload

conditions.Thermal-overload protection is designed to

protect the MAX8875 in the event of fault conditions. For

continuous operation, do not exceed the absolute maxi-

Operating Region and Power Dissipation

The MAX8875’s maximum power dissipation depends

on the thermal resistance of the case and circuit board,

the temperature difference between the die junction

and ambient air, and the rate of air flow. The power dis-

maximum power dissipation is:

the MAX8875 die junction and the surrounding air,

(or

board, copper traces, and other materials to the sur-

rounding air.

The MAX8875’s ground pin (GND) performs the dual

function of providing an electrical connection to system

ground and channeling heat away. Connect GND to the

system ground using a large pad or ground plane.

Reverse-Battery Protection

The MAX8875 has a unique protection scheme that lim-

polarity of these two pins and disconnects the internal

circuitry and parasitic diodes when the battery is

reversed. This feature prevents device damage.

__________Applications Information

Capacitor Selection and

Regulator Stability

For stable operation over the full temperature range

and with load currents up to 150mA, use a 1µF (min)

ceramic output capacitor with an ESR <0.2

Ω. To

reduce noise and improve load-transient response, sta-

bility, and power-supply rejection, use large output

capacitor values, such as 10µF.

Note that some ceramic dielectrics exhibit large capac-

itance and ESR variation with temperature. With

dielectrics such as Z5U and Y5V, it may be necessary

to use 2.2µF or more to ensure stability at temperatures

should be sufficient at all operating temperatures. Also,

for high-ESR tantalum capacitors, 2.2µF or more and a

larger case size may be needed to maintain ESR in the

stable region. For a pin-compatible, functionally equiva-

lent device for use with a higher ESR output capacitor,

see the MAX8885. A graph of the Region of Stable

Operating Characteristics.

PSRR and Operation from

Sources Other than Batteries

The MAX8875 is designed to deliver low dropout voltages

and low quiescent currents in battery-powered systems.

Power-supply rejection is 60dB at low frequencies. See

the Power-Supply Rejection Ratio vs. Frequency graph in

the Typical Operating Characteristics.

Improve supply-noise rejection and transient response

by increasing the values of the input and output bypass

capacitors. The Typical Operating Characteristics show

the MAX8875’s line- and load-transient responses.

Dropout Voltage

A regulator’s minimum input-output voltage differential

(or dropout voltage) determines the lowest usable supply

voltage. In battery-powered systems, this will determine

the useful end-of-life battery voltage. Because the

MAX8875 uses a P-channel MOSFET pass transistor,

its dropout voltage is a function of drain-to-source

(see Typical Operating Characteristics):

150mA, Low-Dropout Linear Regulator

with Power-OK Output

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7

Chip Information

TRANSISTOR COUNT: 266