Low-Noise Operation (MAX8882)
An external 0.01µF bypass capacitor at BP, in conjunc-
tion with an internal resistor, creates a lowpass filter.
The MAX8882 exhibits 40µV
RMS
of output voltage noise
with C
BP
= 0.01µF and C
OUT
_ = 4.7µF. (See the Output
Noise Spectral Density graph in the Typical Operating
Characteristics.)
Applications Information
Capacitor Selection and
Regulator Stability
Use a 2.2µF capacitor on the MAX8882/MAX8883 input
and a 2.2µF capacitor on the outputs. Larger input
capacitor values and lower ESRs provide better supply-
noise rejection and line-transient response. To reduce
noise, improve load transients, and for loads up to
160mA, use larger output capacitors (up to 10µF). For
stable operation over the full temperature range and
with load currents up to 80mA, use 2.2µF.
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 4.7µF or more to ensure stability at temperatures
below -10°C. With X7R or X5R dielectrics, 2.2µF is suffi-
cient at all operating temperatures. These regulators
are optimized for ceramic capacitors, and tantalum
capacitors are not recommended.
Use a 0.01µF bypass capacitor at BP (MAX8882) for
low output voltage noise. Increasing the capacitance
will slightly decrease the output noise, but increase the
startup time. (See the Shutdown Response graph in the
Typical Operating Characteristics.)
PSRR and Operation from Sources
Other than Batteries
The MAX8882/MAX8883 are designed to deliver low
dropout voltages and low quiescent currents in battery-
powered systems. Power-supply rejection is 62dB at
low frequencies and rolls off above 100kHz. (See the
PSRR vs. Frequency graph in the Typical Operating
Characteristics.)
When operating from sources other than batteries,
improved supply-noise rejection and transient response
can be achieved by increasing the values of the input
and output bypass capacitors and through passive fil-
tering techniques.
Dropout Voltage
A regulator’s minimum input-output voltage differential
(or dropout voltage) determines the lowest usable sup-
ply voltage. In battery-powered systems, this deter-
mines the useful end-of-life battery voltage. Because
the MAX8882/MAX8883 use a P-channel MOSFET pass
transistor, their dropout voltage is a function of drain-to-
source on-resistance (R
DS(ON)
) multiplied by the load
current (see the Typical Operating Characteristics).
Chip Information
TRANSISTOR COUNT: 493
PROCESS: BiCMOS
MAX8882/MAX8883
Dual, Low-Noise, Low-Dropout, 160mA Linear
Regulators in SOT23
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