YB1253
300mA, Low Power, High PSRR LDO Regulator
Functional Block Diagram
VIN
EN
Vref
VOUT
Thermal
shutdown
Short Circuit
Protection
GND
Figure 3 : Function diagram
Functional Description
The YB1253 is an ultra-low-noise, low-quiescent
current, low-dropout linear regulator. It is supplied in
a SOT-23 / SOT-25 / SOT-89 package for different
applications. YB1253 can supply load current up to
300mA (typical operation, not maximum) with good
line and load regulation. Output voltages are preset
and ranging from 1.2V to 3.6V.
As shown in the
Functional Block Diagram,
the
YB1253 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
YB1253 Rev. 1.5
and amplifies the difference. If the feedback voltage
is lower than the reference voltage, the gate of the
pass-transistor 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 gate of the pass transistor is pulled high,
allowing less current to pass to the output.
Stability
The YB1253 is a high performance LDO
emphasizing stability with low output capacitance. It
is able to maintain stability with an output capacitor
as low as 1.0µF. The output capacitor can also be
increased to optimize performance. The YB1253 will
remain stable and in regulation with no load, unlike
many other voltage regulators.
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YOBON [ YOBON TECHNOLOGIES,INC. ]
