RT2517A
Functional Block Diagram
R
SENSE
VIN
V
PUMP
-
+
VOUT
-
+
ADJ
V
IN
EN
Thermal
Shutdown
V
OUT
V
IN
+
-
V
IN
Reference
Generator
GND
Reverse Voltage
Shutdown
Operation
The RT2517A is a low input voltage low dropout LDO that
can support the input voltage range from 2.2V to 6V and
the output current can be up to 1A. The RT2517A uses
internal charge pump to achieve low input voltage operation
and the internal compensation network is well designed
to achieve fast transient response with good stability.
In steady-state operation, the feedback voltage is
regulated to the reference voltage by the internal regulator.
When the feedback voltage signal is less than the
reference, the on resistance of the power MOSFET is
decreased to increase the output current through the power
MOSFET, and the feedback voltage will be charge back to
reference. If the feedback voltage is less than the
reference, the power MOSFET current is decreased to
make the output voltage discharge back to reference by
the loading current.
Reverse Current Protection
The reverse current protection is guarantee by the N-
MOSFET with bulk capacitors connected to GND and the
internal circuit. The reverse voltage detection circuit shuts
the total loop down if the output voltage is higher than
input voltage.
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
Output Under-Voltage Protection (UVP) and Over-
Current Fold-Back
When the feedback voltage is lower than 0.15V after
internal soft-start end, the UVP is triggered. If the over-
current condition is trigged during UVP state, the OC limit
current will be decreased to limit the output power and
change into re-soft start state at the same time.
Soft-Start
An internal current source charges an internal capacitor
to build the soft-start ramp voltage. The typical soft-start
time is 150μs. During the soft-start state, the output
current will be limited to prevent the inrush current.
Over-Temperature Protection (OTP)
The RT2517A has an over-temperature protection. When
the device triggers the OTP, the device shuts down until
the temperature back to normal and move to re-soft start
state.
is a registered trademark of Richtek Technology Corporation.
DS2517A-02 August 2018
www.richtek.com
3
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
