XC9511A1434 TOREX [Torex Semiconductor], XC9511A1434 Datasheet - Page 10

• Manufacturer Part Number: XC9511A1434
• Description: Synchronous Step-Down DC/DC Converter with built-in LDO Regulator in parallel plus Voltage Detector
• Manufacturer: TOREX [Torex Semiconductor]

.
10/35
●High Speed LDO Voltage Regulator
●Voltage Detector
■OPERATIONAL EXPLANATION (Continued)
XC9511
The voltage regulator block of the XC9511 series consists of a reference voltage source, error amplifier, and current
limiter circuit. The voltage divided by split resistors is compared with the internal reference voltage by the error amplifier.
The P-channel MOSFET, which is connected to the V
output voltage at the V
achievable even if used with low ESR capacitors as a phase compensation circuit is built-in.
<Reference Voltage Source>
The reference voltage source provides the reference voltage to ensure stable output voltage of the regulator.
<Error Amplifier>
The error amplifier compares the reference voltage with the signal from V
Pch driver transistor.
<Current Limit Circuit>
The voltage regulator block includes a combination of a constant current limiter circuit and a foldback circuit. The
voltage regulator senses output current of the built-in P channel output driver transistor inside. When the load current
reaches the current limit level, the current limiter circuit operates and the output voltage of the voltage regulator block
drops. As a result of this drop in output voltage, the foldback circuit operates, output voltage drops further and the load
current decreases. When the V
The detector block of the XC9511 series detects output voltage from the V
VR
<U.V.L.O. Circuit>
When the V
pulse output caused by unstable operation of the internal circuitry. When the V
switching operation takes place. By releasing the U.V.L.O. function, the IC performs the soft start function to initiate
output startup operation. The soft start function operates even when the V
U.V.L.O. operating voltage. The U.V.L.O. circuit does not cause a complete shutdown of the IC, but causes pulse
output to be suspended; therefore, the internal circuitry remains in operation.
OUT
internally. (N channel Open Drain Type)
IN
pin voltage becomes 1.4 V or lower, the P-channel output driver transistor is forced OFF to prevent false
Series
ROUT
pin is controlled and stabilized by a system of negative feedback. A stable output voltage is
ROUT
and GND pin are shorted, the load current of about 30mA flows.
ROUT
pin, is then driven by the subsequent output signal. The
OUT
DOUT
, and the amplifier controls the output of the
IN
pin while sensing either V
pin voltage falls momentarily below the
IN
pin voltage becomes 1.8 V or higher,
DD
, D
COUT
, or