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XC6218
Series
<Output Voltage Regulator Control>
The XC6218 series consists of a reference voltage source, an error amplifier, current limit circuit, and a phase
compensation circuit plus a driver transistor. The voltage, divided by resistors R11 & R12, which are connected to the
V
OUT pin is compared with the internal reference voltage by the error amplifier. The P-channel MOSFET, which is
connected to the V
OUT pin, is then driven by the subsequent output signal. The output voltage at the VOUT pin is
controlled & stabilized by negative feedback. The current limit circuit and short circuit protection operate in relation to
the level of output current.
<Current Limit, Short-Circuit Protection>
The XC6218 series includes a current limit circuit, which aid the operations of the current limiter and short-circuit
protection. When the load current reaches the current limit level (300mA, TYP.), the current limiter circuit operates and
output voltage drops. The circuit operates to decrease the current limit as the load impedance decreases further and
the output voltage drops. When the output pin is shorted, a current of about 50mA flows.
■ NOTES ON USE
1. Please use this IC within the stated absolute maximum ratings. The IC is liable to malfunction should the ratings be
exceeded.
2. Where wiring impedance is high, operations may become unstable due to noise and/or phase lag depending on output
current.
3.
The XC6218 series oscillates normally even without an input capacitor, CIN, or an output capacitor, CL, because the series
compensates by the phase compensation circuit. However, when an input wiring is long, about 0.1μF to 1.0μF of the input capacitor,
C
IN, is required for stabilizing input. When an under-shoot or over-shoot is large at transient response, about 0.1μF to 1.0μF of
output capacitor, which prevents output fluctuation occurred by load fluctuation, is also recommended.
Please wire the input
capacitor (C
IN) and the output capacitor (CL) as close to the IC as possible. Please wire the input capacitor (CIN) and
the output capacitor (C
L) as close to the IC as possible.
4. When the input voltage starts from 0V, over-shoot may occur because of the slope of the input rising. In order to avoid
the over-shoot, please use the IC by setting the slope of the input rising within 0.1V/ms.
■OPERATIONAL EXPLANATION
