RT8223P
ENTRIPx or cycle VIN to reset the UVP fault latch and
restart the controller.
Shutdown Mode
The RT8223P SMPS1, SMPS2, VREG3 and VREG5 have
independent enabling controls. Drive EN, ENTRIP1 and
ENTRIP2 below the precise input falling-edge trip level to
place the RT8223P in its low power shutdown state. The
RT8223P consumes only 20μA of input current while in
shutdown. When shutdown mode is activated, the
reference turns off. The accurate 0.4Vfalling-edge threshold
on the EN pin can be used to detect a specific analog
voltage level as well as to shutdown the device. Once in
shutdown, the 2.4V rising-edge threshold activates,
providing sufficient hysteresis for most applications.
Thermal Protection
The RT8223P features thermal shutdown protection to
prevent overheat damage to the device. Thermal shutdown
occurs when the die temperature exceeds 150°C. All
internal circuitry is inactive during thermal shutdown. The
RT8223P triggers thermal shutdown if VREGx is not
supplied from VOUTx, while the input voltage on VIN and
the drawing current from VREGx are too high. Even if
VREGx is supplied from VOUTx, large power dissipation
on automatic switches caused by overloading VREGx,
may also result in thermal shutdown.
Power Up Sequencing and On/Off Controls (ENC)
ENTRIP1 and ENTRIP2 control the SMPS power up
sequencing. When the RT8223P is in single channel mode,
ENTRIP1 or ENTRIP2 enables the respective output when
ENTRIPx voltage descends below 3V. Furthermore, the
RT8223P can also be in dual channel mode. In this mode,
outputs are enabled when ENC voltage rises above 2V.
Discharge Mode (Soft-Discharge)
When ENTRIPx is low and a transition to standby or
shutdown mode occurs, or the output under voltage fault
latch is set, the output discharge mode will be triggered.
During discharge mode, the output capacitors' residual
charge will be discharged to GND through an internal
switch.
Table 2. Operation Mode Truth Table
Condition
MODE
Comment
Transitions to discharge mode after a VIN POR and after
REF becomes valid. VREG5, VREG3, and REF remain
active.
Power UP VREGx < UVLO threshold
EN = high, VOUT1 or VOUT2
enabled
RUN
Normal Operation.
Over Voltage Either output > 111% of the nominal LGATEx is forced high. VREG3, VREG5 and REF active.
Protection level. Exited by VIN POR or by toggling EN, ENTRIPx, ENC
Under
Voltage
Either output < 52% of the nominal Both UGATEx and LGATEx are forced low and enter
level after 3ms time-out expires and discharge mode. VREG3, VREG5 and REF are active.
Protection output is enabled
Exited by VIN POR or by toggling EN, ENTRIPx, ENC
Either SMPS output is still high in
Discharge either standby mode or shutdown
mode
During discharge mode, there is one path to discharge the
outputs capacitor residual charge. That is output capacitor
discharge to GND through an internal switch.
ENTRIPX < startup threshold,
EN = high.
Standby
VREG3, VREG5 and REF are active.
Shutdown EN = low
Thermal
Shutdown
All circuitry off.
All circuitry off. Exit by VIN POR or by toggling EN, ENTRIPx,
ENC
T > 150°C
J
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DS8223P-01 June 2011
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
