XC9303B093KR-G Torex Semiconductor, XC9303B093KR-G Datasheet - Page 5

• Manufacturer Part Number: XC9303B093KR-G
• Description: Specifications: PWM Type: Controller ; Number of Outputs: 1 ; Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) ; Packaging: Tape & Reel (TR) ; Duty Cycle: 88% ; Voltage - Supply: 2 V ~ 10 V ; Frequency - Max: 345kHz ; Buck: Yes ; Boost: Yes
• Manufacturer: Torex Semiconductor

The XC9303 series are synchronous step-up & down DC/DC converter controller ICs with built-in high speed, low ON
resistance drivers.
<Error Amp.>
The error amplifier is designed to monitor the output voltage and it compares the feedback voltage (FB) with the reference
voltage. In response to feedback of a voltage lower than the reference voltage, the output voltage of the error amp.
decreases.
<OSC Generator>
This circuit generates the oscillation frequency, which in turn generates the source clock.
<Ramp Wave Generator>
The ramp wave generator generates a saw-tooth waveform based on outputs from the phase shift generator.
<PWM Comparator>
The PWM Comparator compares outputs from the error amp. and saw-tooth waveform. When the voltage from the error
amp's output is low, the external switch will be set to ON.
<PWM/PFM Controller>
This circuit generates PFM pulses. Control can be switched between PWM control and PWM/PFM automatic switching
control using external signals. The PWM/PFM automatic switching mode is selected when the voltage of the PWM pin is less
than 0.2V, and the control switches between PWM and PFM automatically depending on the load. As the PFM circuit
generates pulses based on outputs from the PWM comparator, shifting between modes occurs smoothly. PWM control mode
is selected when the voltage of the PWM pin is more than 0.65V. Noise is easily reduced with PWM control since the switching
frequency is fixed. Control suited to the application can easily be selected which is useful in audio applications, for example,
where traditionally, efficiencies have been sacrificed during stand-by as a result of using PWM control (due to the noise
problems associated with the PFM mode in stand-by).
<Synchronous, blank logic>
The synchronous, blank logic circuit is to prevent penetration of the transistor connected to EXT1 and EXT2.
<Vref with Soft Start>
The reference voltage, Vref (FB pin voltage)=0.9V, is adjusted and fixed by laser trimming (for output voltage settings, please
refer to next page). To protect against inrush current, when the power is switched on, and also to protect against voltage
overshoot, soft-start time is set internally to 10ms. It should be noted, however, that this circuit does not protect the load
capacitor (C
maintains a balance between the two inputs of the error amps and controls the EXT pin's ON time so that it doesn't increase
more than is necessary.
<Chip Enable Function>
This function controls the operation and shutdown of the IC. When the voltage of the CE pin is 0.2V or less, the mode will be
chip disable, the channel's operations will stop. The EXT1 pin will be kept at a high level (the external P-ch MOSFET will be
OFF) and the EXT2 pin will be kept at a high level (the external N-ch MOSFET will be ON). When CE pin is in a state of chip
disable, current consumption will be no more than 3.0μA. When the CE pin's voltage is 0.65V or more, the mode will be chip
enable and operations will recommence. With soft-start, 95% of the set output voltage will be reached within 10ms (TYP.)
from the moment of chip enable.
<Output Voltage Setting>
Output voltage can be set by adding external split resistors. Output voltage is determined by the following equation, based on
the values of R
The value of C
to 12kHz. Adjustments are required from 1kHz to 50kHz depending on the application, value of inductance (L), and value of load
capacity (C
■ OPERATIONAL EXPLANATION
V
OUT
L
).
L
) from inrush current. With the Vref voltage limited and depending upon the input to the error amps, the operation
FB1
FB11
= 0.9
(C
(R
×
FB2
FB21
( R
), speed-up capacitor for phase compensation, should be fzfb= 1 / (2
FB11
) and R
+ R
FB12
FB12
(R
) / R
FB22
FB12
). The sum of R
FB11
(R
FB21
) and R
FB12
(R
FB22
×π×
) should normally be 1 MΩor less.
C
FB1
×
R
FB11
) which is equal
XC9303
Series
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