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XC6701
Series
■ OPERATIONAL EXPLANATION
<Output Voltage Control>
The voltage divided by resistors R1 & R2 is compared with the internal reference voltage by the error amplifier. The
P-channel MOSFET, which is 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, short protect
circuit and thermal protection circuit operate in relation to the level of output current and heat generation. Further, the IC’s
internal circuitry can be shutdown via the CE pin’s signal.
<Short-Circuit Protection>
The XC6701 series includes a current fold-back circuit as a short circuit protection. When the load current reaches the
current limit level, the current fold-back circuit operates and output voltage drops. The output voltage drops further and
output current decreases. When the output pin is shorted, a current of about 30mA flows.
<CE Pin>
The IC’s internal circuitry can be shutdown via the signal from the CE pin with the XC6701A/B series. In shutdown mode,
output at the VOUT pin will be pulled down by R1 and R2 to the VSS level. Note that as the XC6701B series’ operations will
become unstable with the CE pin open. We suggest that you use this IC with either a VIN voltage or a VSS voltage input at
the CE pin. If this IC is used with the correct specifications for the CE 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 if a
medium voltage is applied.
<Thermal Shutdown>
When the junction temperature of the built-in driver transistor reaches the temperature limit level (150℃ TYP.), the thermal
protection circuit operates and the driver transistor will be set to OFF. The IC resumes its operation when the thermal
shutdown function is released and the IC’s operation is automatically restored because the junction temperature drops to
the level of the thermal shutdown release voltage.
<Minimum Operating Voltage>
For the stable operation of the IC, over 2.0V of input voltage is necessary. The output voltage may not be generated
normally if the input voltage is less than 2.0V.
1. For temporary, transitional voltage drop or voltage rising phenomenon, the IC is liable to malfunction should the ratings be
exceeded.
2. Where wiring impedance is high, operations may become unstable due to the noise and/or phase lag depending on output
current. Please strengthen VIN and VSS wiring in particular.
3. Phase compensation inside the IC is performed in the XC6701 series. Therefore, an abnormal oscillation does not occur
even if there is no output capacitor CL. An input capacitor CIN around 0.1μF~1.0μF between the VIN pin and the VSS pin
is required for input stability. Also, the output voltage fluctuation such as under shoot or over shoot, which occurs
because of the load change can be controlled by placing the output capacitor CL around 0.1μF~1.0μF between the VOUT
pin and VSS pin. The input capacitor (CIN) and the output capacitor (CL) should be placed to the IC as close as possible
with a shorter wiring.
4. When the IC is operated with no load, the output voltage may increase in the high temperature beyond operating range.
5. Torex places an importance on improving our products and its reliability.
However, by any possibility, we would request user fail-safe design and post-aging treatment on system or equipment.
■ NOTES ON USE
R1
R2