
7/11 
XC6601
Series
<Voltage Regulator> 
The voltage divided by resistors R1 & R2 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 V
OUT 
pin is 
controlled & stabilized by a system of negative feedback.  
V
BIAS
 pin is power supply pin for output voltage control circuit, protection circuit and CE circuit.  When output current increase, 
the V
BIAS
 pin supplies output current also. VIN pin is connected to a driver transistor and provides output current.  
In order to obtain high efficient output current through low on-resistance, please take enough Vgs (=V
BIAS
 – V
OUT
) of the driver 
transistor. Output current triggers operation of constant current limiter and foldback circuit, heat generation triggers operation of 
thermal shutdown circuit, the driver transistor circuit is forced OFF when V
BIAS
 or V
IN
 voltage goes lower than U.V.L.O. voltage.  
Further, the IC's internal circuitry can be shutdown via the CE pin's signal. 
XC6601A series
<
Low ESR Capacitor
> 
With the XC6601 series, a stable output voltage is achievable even if used with low ESR capacitors, as a phase compensation 
circuit is built-in. The output capacitor (C
L
) should be connected as close to V
OUT
 pin and V
SS
 pin to obtain stable phase 
compensation. Values required for the phase compensation are as the table below.  
For a stable power input, please connect an bias capacitor (C
BIAS
 ) of 1.0
please connect an input capacitor (C
IN
) of 1.0
F between the V
IN 
pin and the V
SS 
pin.  In order to ensure the stable phase 
compensation while avoiding run-out of values, please use the capacitor (C
BIAS
, C
IN
, C
L
 ) which does not depend on bias or 
temperature too much. The table below shows recommended values of C
BIAS
, C
IN
, C
L
.  
F between the V 
BIAS
pin and the V
SS 
pin. Also, 
Recommended Values of C
BIAS, 
C
IN, 
C
L
BIAS CAPACITOR 
C
BIAS
C
BIAS
=1.0μF 
INPUT CAPACITOR 
C
IN
C
IN
=1.0μF 
OUTPUT CAPACITOR 
C
L
C
L
=4.7μF 
SETTING VOLTAGE 
0.7V~1.8V 
OPERATIONAL EXPLANATION