Dual Channel 200mA LDO Regulator
Functional Block Diagram
YB1220
Functional Description
The YB1220 consists of two low-noise,
low-quiescent current, low-dropout linear
regulators and is supplied in a small
SOT-26 package suitable for portable and
battery-powered
applications.
Each
channel can independently supply loads up
to 200mA (typical operation, not maximum)
and output voltages are preset and ranging
from 1.2V to 3.6V.
As shown in the
Functional Block Diagram,
the YB1220 consists of a single reference
generating circuit, two error amplifiers, two
P-channel pass transistors, independent
internal feedback voltage dividers, two
short circuit current limiters and one
thermal shutdown protection circuit.
The internal reference is connected to the
error amplifier’s inverting input. The error
amplifier compares this reference with the
feedback voltage and amplifies the
YB1220 MRev.1.1
difference. If the feedback voltage is lower
than the reference voltage, the gate of
pass-transistor is pulled low, allowing more
current to pass to the output and increasing
the output voltage. If the feedback voltage
is too high, the gate of pass transistor is
pulled high, resulting in less current to the
output.
Stability
The YB1220 is a high performance LDO
emphasizing stability with low output
capacitance. It is able to maintain stability
with an output capacitor as low as 1.0uF.
The output capacitor can also be increased
to optimize performance. The YB1220 will
remain stable and in regulation with no load,
unlike many other voltage regulators.
Internal P-Channel Pass Transistor
The YB1220 features a low impedance
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YOBON [ YOBON TECHNOLOGIES,INC. ]
