MAX8532
Low-Noise, Low-Dropout,
200mA Linear Regulator in UCSP
6 _______________________________________________________________________________________
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 T
J
= +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 T
J
= +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 = I
OUT
(V
IN
- V
OUT
).
Maximum power dissipation:
P
MAX
= (T
J
- T
A
)/(θ
JB
+ θ
BA
)
where T
J
- T
A
is the temperature difference between the
MAX8532 die junction and the surrounding air, θ
JB
(or
θ
JC
) is the thermal resistance of the package, and θ
BA
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 40µV
RMS
output voltage noise
with C
BP
= 0.01µF and C
OUT
= 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.
