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MAX8532

Low-Noise, Low-Dropout, 200mA Linear Regulator in UCSP

Maxim Integrated 

Low-Noise, Low-Dropout,

200mA Linear Regulator in UCSP

Current Limit

The MAX8532 contains an independent current limiter,

which monitors and controls the pass transistor’s gate

voltage, limiting the output current to 210mA (min). The

output can be shorted to ground indefinitely without

damaging the part.

Thermal-Overload Protection

Thermal-overload protection limits total power dissipa-

tion in the MAX8532. When the junction temperature

exceeds TJ = +160°C, the thermal sensor signals the

shutdown logic, turning off the pass transistor and allow-

ing the IC to cool. The thermal sensor turns the pass

transistor on again after the IC’s junction temperature

cools by 10°C, resulting in a pulsed output during contin-

uous thermal-overload conditions.

Thermal-overload protection is designed to protect the

MAX8532 in the event of fault conditions. For continual

operation, do not exceed the absolute maximum junc-

tion temperature rating of TJ = +150°C.

Operating Region and Power Dissipation

The MAX8532’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 airflow rate. The power dissi-

pation across the device is P = IOUT (VIN - VOUT).

Maximum power dissipation:

PMAX = (TJ - TA)/(θJB + θBA)

where TJ - TA is the temperature difference between the

MAX8532 die junction and the surrounding air, θJB (or

θJC) is the thermal resistance of the package, and θBA is

the thermal resistance through the printed circuit board,

copper traces, and other materials, to the surrounding air.

Low-Noise Operation

An external 0.01µF bypass capacitor at BP, in conjunc-

tion with an internal resistor, creates a lowpass filter.

The MAX8532 exhibits 40µVRMS output voltage noise

with CBP = 0.01µF and COUT = 2.2µF (see the Output

Noise Spectral Density vs. Frequency graph in the

Typical Operating Characteristics).

Applications Information

Capacitor Selection

and Regulator Stability

Use a 2.2µF capacitor on the MAX8532’s input. Larger

input capacitor values with lower ESR provide better

supply-noise rejection and line-transient response. To

reduce noise and improve load transients, use large

output capacitors up to 10µF. For stable operation over

the full temperature range and with rated maximum

load currents, use a minimum of 2.2µF (or 1µF for

<150mA loading) for OUT.

Note that some ceramic dielectrics exhibit large capac-

itance and ESR variation with temperature. With

dielectrics such as Z5U and Y5V, use 4.7µF or more to

ensure stability at temperatures below -10°C. With X7R

or X5R dielectrics, 2.2µF is sufficient at all operating

temperatures. These regulators are optimized for

ceramic capacitors. Tantalum capacitors are not rec-

ommended.

PSRR and Operation from

Sources Other than Batteries

The MAX8532 is designed to deliver low dropout volt-

ages and low quiescent currents in battery-powered sys-

tems. Power-supply rejection is 62dB at low frequencies

(see the Power-Supply Rejection Ratio vs. Frequency

graph in the Typical Operating Characteristics).

When operating from sources other than batteries,

improve supply-noise rejection and transient response

by increasing the values of the input and output bypass

capacitors and through passive filtering techniques.

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