XC9510 TOREX SEMICONDUCTOR LTD., XC9510 Datasheet - Page 8

• Manufacturer Part Number: XC9510
• Description: Xc9510 Synchronous Step-down Dc/dc Converter With Built-in Ldo Regulator In Series Plus Voltage Detector
• Manufacturer: TOREX SEMICONDUCTOR LTD.

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■TYPICAL APPLICATION CIRCUIT
■OPERATIONAL EXPLANATION
The XC9510 series consists of a synchronous step-down DC/DC converter, a high speed LDO voltage regulator, and a
voltage detector. Since the LDO voltage regulator is stepped-down from the DC/DC’s output,high efficiency and low noise is
possible even at lower output voltages.
●DC/DC Converter
XC9510
The series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator, phase
compensation circuit, output voltage adjustment resistors, driver transistor, synchronous switch, current limiter circuit,
U.V.L.O. circuit and others. The series ICs compare, using the error amplifier, the voltage of the internal voltage
reference source with the feedback voltage from the V
performed on the resulting error amplifier output, to input a signal to the PWM comparator to determine the turn-on time
during PWM operation. The PWM comparator compares, in terms of voltage level, the signal from the error amplifier
with the ramp wave from the ramp wave circuit, and delivers the resulting output to the buffer driver circuit to cause the
Lx pin to output a switching duty cycle. This process is continuously performed to ensure stable output voltage. The
current feedback circuit monitors the P-channel MOS driver transistor current for each switching operation, and
modulates the error amplifier output signal to provide multiple feedback signals. This enables a stable feedback loop
even when a low ESR capacitor, such as a ceramic capacitor, is used, ensuring stable output voltage.
<Reference Voltage Source>
The reference voltage source provides the reference voltage to ensure stable output voltage of the DC/DC converter.
<Ramp Wave Circuit>
The ramp wave circuit determines switching frequency. The frequency is fixed internally and can be selected from
300kHz, 600 kHz and 1.2 MHz. Clock pulses generated in this circuit are used to produce ramp waveforms needed for
PWM operation, and to synchronize all the internal circuits.
<Error Amplifier>
The error amplifier is designed to monitor output voltage. The amplifier compares the reference voltage with the
feedback voltage divided by the internal split resistors. When a voltage lower than the reference voltage is fed back, the
output voltage of the error amplifier increases. The gain and frequency characteristics of the error amplifier output are
fixed internally to deliver an optimized signal to the mixer.
4.7μF(ceramic, TAIYO YUDEN)
*1 The DC/DC converter of the XC9510 series automatically switches between synchronous / non-synchronous. The Schottky
*2 Please be noted that the recommend value above of the CL2 may be changed depending on the input voltage value and setting
diode is not normally needed. However, in cases where high efficiency is required when using the DC/DC converter during in the
light load while in non-synchronous operation, please connect a Schottky diode externally.
voltage value.
CIN
Series
SOP-8 (TOP VIEW)
10μF(ceramic, TAIYO YUDEN)
CL1
OUT
pin through split resistors.
IR
IR
OUT
OUT<
>300mA
300mA
1.2MHz
600kHz
300kHz
FOSC
4.7μF (ceramic, TAIYO YUDEN)
10μF (ceramic, TAIYO YUDEN)
4.7μH (CDRH4D28C, SUMIDA)
CL2 *
10μH (CDRH5D28, SUMIDA)
22μH (CDRH6D28, SUMIDA)
Phase compensation is
2
L