R1171 Datasheet, PDF (20/24 Pages) RICOH electronics devices division – 2.0A/1.5A LDO REGULATOR

R1171x
Technical Notes on External Components and Typical Application
1. Phase Compensation
In these ICs, phase compensation is made with the output capacitor for securing stable operation even if the
load current is varied. For this purpose, use a capacitor with the capacitance range from 4.7μF to 10.0μF, as CL.
In case that using a tantalum capacitor and the ESR of the tantalum capacitor is too large, unstable operation
may result. Fully evaluation is necessary for the whole circuit with considering the frequency characteristic.
2. Mounting on PCB
Make VDD and GND lines sufficient. If their impedance is high, large current may flow and the pick-up noise or
unstable operation may result. Therefore use a capacitor with a capacitance range from 4.7μF to 10.0μF
between VDD pin and GND pin as close as possible.
Further, set an output capacitor between VOUT pin and GND pin for phase compensation as close as possible.
(Refer to the example of typical application)
CE
VDD
VOUT
OUT
IN
R1171xxx1B
CL
CI
GND
R1171Sxx1B Typical Application
1.5V ^<= VOUT<1.8V : CI=10μF (Ceramic),CL=10μF (Ceramic)
1.8V ^<= VOUT ^<= 5.0V : CI=4.7μF (Ceramic),CL=4.7μF (Ceramic)
3. Output Short Protection Function
In the R1171x Series, the output short protection function is built in, further, if the output is short to the GND or
other voltage line, the chip inside is heating, as a result, in case that the junction temperature becomes equal or
more than 150°C (Typ.), the built-in thermal shutdown circuit works. If the junction temperature becomes equal
or more than 150°C (Typ.), the IC is protected by the output short protection circuit and the thermal shutdown
circuit.
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