Dual Channel 200mA LDO Regulator
P-channel MOSFET pass transistor. This
provides several advantages over similar
designs using a PNP pass transistor,
including low operating power and longer
battery life. The YB1220 consumes only
90µA around of quiescent current under
Output Short-Circuit Current Limit
The YB1220 includes two current limiters,
which monitor and control the pass
transistor’s gate voltage, limiting the output
current to about 80mA, for example, in a
short-circuit output situation.
The YB1220 also features a low-power
shutdown mode. It consists of independent
switches to turn off different channel. The
two LDOs are allowed to work in both
active, only one active or both disabled to
keep the lowest current consumption. In the
both shutdown mode, the internal
functional blocks, such as voltage
reference and the error amplifiers, are
turned off completely, and the quiescent
current is less than 1µA. In the single
shutdown mode, the reference circuit and
the active side error amplifier remain
functional whereas the disabled error
amplifier gets into shutdown mode.
Thermal Protection Shutdown
The thermal protection shutdown function
protects the device from operating in over
temperature condition. When the junction
temperature exceeds +160°C, the thermal
sensor signals the shutdown logic, turning
off the pass transistor and allowing the IC
to cool down. The thermal sensor turns the
pass transistor on again after the IC’s
junction temperature drops to +140°C.
The YB1220 includes a soft-start circuitry to
limit inrush current at turn-on. During power
up, the output capacitor and output load are
charged with a reduced output current.
Shortly after the initial power up, the
soft-start feature is terminated and normal
operation is resumed.
The YB1220 comes with an active-high
enable pin that allows the regulator to be
enabled. Forcing the enable pin low
disables the regulator and puts it into the
shutdown mode. This pin cannot be left
floating as it may cause an undetermined
It is recommended to use a 1.0µF capacitor
on the YB1220 input and a 1.0µF capacitor
on the output. For high regulation
performance, larger input capacitor values
and lower ESRs provide better noise
rejection and line-transient response. The
output noise, load-transient response,
stability, and power-supply rejection can be
improved by using large output capacitors.
Low ESR ceramic capacitors provide
optimal performance and save space.
The transient response can be improved by
increasing the values of the input and
output bypass capacitors, and through
passive filtering techniques.