XC6411/XC6412
Series
■OPERATIONAL
EXPLANATION
<Output Voltage Control>
The voltage, divided by resistors R11 & R12 for a regulator 1 and R21 & R22 for a regulator 2 is compared with the internal
reference voltage by the error amplifier. These resistors are connected to the V
OUT
pin. 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 and
stabilized by a system of negative feedback. The current limit circuit operates when the load current reaches the current limit
level.
●XC6411P
Series
●XC6412B
Series (SOT-26)
●XC6412C
Series (USP-6C)
*Preliminary
VOUT 1 VIN1
Current
Lim it1
+
-
Voltage
Reference1
VOUT 2
Current
Lim it2
+
-
Voltage
Reference2
R22
VSS
R21
ON/OFF
Control
Current
Lim it2
EN2
+
-
Voltage
Reference2
R21
R12
R11
Current
Lim it1
+
-
Voltage
Reference1
R12
R11
VOUT 1
VIN1
Current
Lim it1
+
-
Voltage
Reference1
R12
R11
VOUT 1 VIN
VIN2
VOUT 2 VIN2
Current
Lim it2
EN2
VSS
ON/OFF
Control
+
-
Voltage
Reference2
R22
R21
VOUT 2
R22
VR2 Each Circuit
VR2 Each Circuit
VSS
* Diodes shown in the above circuit are ESD protection diodes and parasitic diodes.
、
、
<Dual Inputs>
The power input voltage pin of the regulator 1 and regulator 2 in the XC6411P/XC6412C series operate independently of
absolute, which makes the circuit structure efficiently.
<Short Protection Circuit>
The XC6411P/6412 series’ regulator offers short-circuit protection by means of a built-in foldback circuit. When the load current
reaches the current limit level, the fixed current limiter circuit operates and output voltage drops. As a result of this drop in
output voltage, the foldback circuit operates, the output voltage drops further and output current decreases. When the output
voltage pin is shorted, a current of about 50mA flows.
<EN2 Pin>
The regulator 2’s internal circuitry can be operated or shutdown via the signal from the EN2 pin with the XC6412 series. In so
doing the regulator 1 maintains an operational state constantly. In shutdown mode, output at the V
OUT2
pin will be pulled down
to the V
SS
level via R21 & R22. Note that the XC6412 series’ regulator is “High Active/No Pull-Down”, operations will become
unstable with the EN2 pin open. We suggest that you use this IC with either a V
IN
voltage or a V
SS
voltage input at the EN2 pin.
If this IC is used with the correct specifications for the EN pin, the operational logic is fixed and the IC will operate normally.
However, supply current may increase as a result of through current in the IC's internal circuitry.
■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. As for the XC6412 series, internally achieved phase compensation makes a stable operation of the IC possible even when
there is no output capacitor (C
L
). In order to stabilize the V
IN
’s voltage level, we recommend that an input capacitor (C
IN
) of
about 0.1 to 1.0μF be connected between each V
IN
pin and the V
SS
pin. Moreover, during transient response, so as to
prevent an undershoot or overshoot, we recommend that the output capacitor (CL) of about 0.1 to1.0μF be connected
between each V
OUT
pin and the V
SS
pin. However, please wire the input capacitor (C
IN
) and the output capacitor (C
L
) as
close to the IC as possible.
4. The XC6412C series (USP-6C package) is under development.
9/28
TOREX [ TOREX SEMICONDUCTOR ]
