YB1230 – 600mA
Low-Noise LDO Regulator
Functional Block Diagram
IN
EN
SHUTDOWN AND
POWER-ON CONTROL
ERROR
AMP
MOS DRIVER
WITH
LIMIT
P
OUT
THERMAL
SENSOR
REFERENCE
AND NOISE BYPASS
GND
Figure 3. Block Diagram
Functional Description
The YB1230 is an low-noise, low-quiescent
current, low-dropout linear regulator. It is
supplied in a SOT-23 / SOT-25 / SOT-89
package for different applications. These
devices can supply loads up to 600mA. As
shown in the
Functional Block Diagram,
the
YB1230 consists of a reference and noise
bypass circuit, error amplifier, output drive
transistor, internal feedback voltage divider,
thermal sensor, and short circuit current
limiter. 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
difference. If the feedback voltage is lower
than
the
reference
voltage,
the
pass-transistor gate is pulled low. This
allows more current to pass to the output
and increases the output voltage. If the
feedback voltage is too high, the pass
YB1230 MRev 1.4
transistor gate is pulled high, allowing less
current to pass to the output. The parts are
available with preset output voltages
ranging from 1.8V to 3.1V.
Stability
The YB1230 is a high performance LDO
emphasizing stability with low output
capacitance. It is able to maintain stability
with an output capacitor as low as 2.2 uF.
The output capacitor can also be increased
to optimize performance. The YB1230 will
remain stable and in regulation with no load,
unlike many other voltage regulators.
Internal P-Channel Pass Transistor
The YB1230 features a low impedance
P-channel MOSFET pass transistor. This
provides several advantages over similar
designs using a PNP pass transistor,
6
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YOBON [ YOBON TECHNOLOGIES,INC. ]
