XC6225 Datasheet, PDF (9/15 Pages) Torex Semiconductor – 30mA High Speed LDO Regulator

XC6225
Series
˙OPERATIONAL EXPLANATIONç
The voltage divided by resistors R1 & R2 is compared with the internal reference voltage by the error amplifier. The P-channel
MOSFET connected to the VOUT pin, is then driven by the subsequent output signal. The output voltage at the VOUT pin is
controlled and stabilized by a system of negative feedback. The current limit circuit and short-circuit protection circuit operate in
relation to the level of output current. Further, the IC’s entire circuitry is turned off by the input signal to the CE pin.
●BLOCK DIAGRAM
CE
ON/OFF
Control
CE
CE/
each
circuit
-
Error
Amp
+
Current
Limit
V IN
R1 Rdischg
CE/
V OUT
Voltage
Reference
R2
VSS
<Input and Output Capacitors>
The XC6225 needs an output capacitor C_L for phase compensation. Values required for the phase compensation are shown in
the chart below. If a loss of the capacitance happens, the stable phase compensation may not be obtained. Please ensure to
use a capacitor which does not depend on bias or temperature too much. For a stable power input, please connect an input
capacitor C_IN of 1.0ЖF between the V_IN pin and the V_SS pin.
OUTPUT VOLTAGE
0.8V～1.15V
1.2V～1.35V
1.4V～4.0V
4.05V～5.0V
OUTPUT CAPACITOR
C_L=4.7μF
C_L=2.2μF
C_L=1.0μF
C_L=2.2μF
<C_L Auto-Discharge Function>
XC6225B series can discharge the electric charge in the output capacitor (CL), when a low signal to the CE pin, which enables
the whole IC circuit to be turned off, is inputted via the N-channel transistor located between the VOUT pin and the VSS pin (refer
to BLOCK DIAGRAM). The C_L auto-discharge resistance value is set at 780Њ(VOUT=4.0V @ VIN=6.0V at TYP.). The discharge
time of the output capacitor (CL) is set by the C_L auto-discharge resistance (R) and the output capacitor (CL). By setting the time
constant of the CL auto-discharge resistance value [R_DCHG] and the output capacitor value (CL) as Н(Н=C x R_DCHG), the output
voltage after discharge via the N-channel transistor is calculated by the following formula.
V= V_OUT(E) ×e^{-t / τ} or ｔ= τln（V/ V_OUT(E)）
Where
V: Output voltage after discharge
V_{OUT (E)} : Output voltage
t : Discharge time,
τ: C_L auto-discharge resistance R_DCHG ×Output capacitor （C_L）value C
9/15