RT8239A/B/C
21
DS8239A/B/C-06 October 2012
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©
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Table1. Operation Mode Truth Table
Mode Condition
Comment
Power Up
LDOx
< UVLO threshold
Transitions to discharge mode after VIN POR and
after REF becomes valid. LDO5 and LDO3 remain
active.
Run
ENLDO = high, V
OUT1
or V
OUT2
are
enabled
Normal Operation.
Over Voltage
Protection
Either output > 112% of the nominal level.
LGATEx is forced high. LDO3 and LDO5 are active.
Exit by VIN POR or by toggling ENLDO, ENTRIPx,
and ENM.
Under Voltage
Protection
Either output < 58% of the nominal level
after 3ms time-out expires and output is
enabled
Both UGATEx and LGATEx are forced low and
enter discharge mode. LDO3 and LDO5 are active.
Exit by VIN POR or by toggling ENLDO, ENTRIPx,
and ENM.
Discharge
Either output is still high in standby mode
or shutdown mode
During discharge mode, there is one path to
discharge the output capacitors’ residual charge to
GND via an internal switch.
Standby
ENTRIPx or ENM < startup threshold,
ENLDO = high.
LDO3 and LDO5 are active.
Shutdown
ENLDO = low
All circuitry are off.
Thermal
Shutdown
T
J
> 150°C
All circuitry are off. Exit by VIN POR or by toggling
ENLDO, ENTRIPx, and ENM.
Table 2. Power up Sequencing (RT8239A)
ENLDO (V)
ENM (V)
ENTRIP1
(V)
ENTRIP2
(V)
LDO5 LDO3 SMPS1
SMPS2
Low Low X
X Off Off Off Off
“>1.6V”
=> High
Low X X On On Off Off
“>1.6V”
=> High
“>2.3V”
=> High
Off Off On On Off Off
“>1.6V”
=> High
“>2.3V”
=> High
Off On On On Off On
“>1.6V”
=> High
“>2.3V”
=> High
On On On On On On
“>1.6V”
=> High
“>2.3V”
=> High
On Off On On On Off
