Functions

QuestionWhy is the standby current indicated for XC6215 but not for XC6218?
Answer

The standby current is the small current that flows through the IC in the standby mode. XC6218 does not have the CE function, but XC6215 does. Products with the CE function have the standby mode and thus the standby current is indicated. The standby mode of XC6215 means the state where the IC has been turned off by the CE pin.

QuestionWhat does the standby mode mean in the case of the multi channel IC?
Answer

It means the state where the entire IC has been turned off. For Torex products, it means that the pin voltages of EN1 and EN2 are both 0V.

QuestionHow does the GO function of DC/DC converters work? Does it work just like a regulator?
Answer

Torex regard the PWM/PFM automatic switch control function as Green Operation (GO) in the case of DC/DC. The GO function is defined as the switching operation between the PFM mode for a small output current and the PWM mode for a large output current. The PFM control method controls the output current by increasing and decreasing the fall time according to the output current while keeping a pulse width. The PWM control method controls the output current by adjusting the pulse width of the rise time, which keeps the rise/fall time interval constant and increases the efficiency at a heavy load. By switching between the PFM control for a small output current and the PWM control for a large output current, the quiescent current can be controlled for both of heavy and light loads.

QuestionWhat is the difference between the converter and the controller in the case of DC/DC?
Answer

Torex refer to an IC with a built-in driver transistor as a DC/DC converter and an IC with an external transistor is used controlled by the DC/DC as a DC/DC controller. A DC/DC converter without an external transistor in a circuit, the mounting area is reduced with less external items. However, the power dissipation should be taken into consideration because the driver transistor becomes a heat source. DC/DC controller is used, a transistor can be selected suited for the power circuit specification, but the circuit may be larger.

QuestionWhat does the integration protection work?
Answer

When the MAX DUTY state continues for over a certain period, this function holds the output Pch driver transistor in the off state by latching the EXT/output to H. The latched state is not the shutdown. The pulse output is stopped, but the internal circuit is operating. This is an effective protection circuit for a large input-output voltage difference.

QuestionWhat is the soft-start function?
Answer

The function to soften the rise to prevent the inrush current.

QuestionWhy is the DC/DC converter more effective than the voltage regulator?
Answer

In voltage regulators, the Pch MOSFET acts as a variable resistance, and the power loss can be calculated by the multiplication of the flowing current with the input-output differential voltage. In DC/DC converters, the power loss is reduced by the switching operation to gain a high efficiency with the help of inductor energy storage. Since DC/DC converters are composed of several functional elements, it is important to reduce each element resistance for a higher efficiency.

QuestionWhat is the ramp circuit?
Answer

The circuit that defines the switching frequency. An individually generated clock is used to generate the ramp wave necessary for the PWM operation, and each circuit is internally synchronized.

QuestionWhy is a coil required for DC/DC?
Answer

When voltage is applied to the both sides of a coil, the current which flows into the coil increases linearly in proportion to time, and the current in the coil continues to flow even though the switch is turned OFF. The coil plays the role of maintaining the voltage which flows into the CIN and CL to a constant using this characteristic.

QuestionWhat is the ripple voltage of DC/DC?
Answer

When the output voltage waveform is observed, the switching noise can be seen and its one of the components is the ripple voltage.
Since this is a change of voltage when the coil current is smoothened by a CL capacitor, the frequency becomes equal to the frequency of the switching operation.
The approximate level of the ripple voltage can be acquired by the product of the ESR of the coil current value and the CL capacitor.

QuestionWhat is the spike noise of DC/DC?
Answer

The spike noise is outputted when the switching waveform switches ON/OFF.
The frequency becomes a high frequency noise of tens of MHz or more.

QuestionWhat is the foldback circuit of LDO?
Answer

This is one of the circuits which protect ICs from unexpected situations, such as the generation of heat.

  1. When the output current exceeds the set value, the current limiting function activates to suppress currents beyond the set value from flowing.
  2. As a result, the output voltage drops.
  3. When the output voltage drops to a certain value, the foldback circuit activates and the output voltage is reduced further while reducing the output current, which protects ICs from unexpected situations.
This is the foldback circuit.

QuestionWhat is a Moisture Sensitivity level of a package?
Answer

Please open the PDF file of the Reliability Test Data in the series detail page. The MSL is shown in the "Resistance to Soldering Heat" item of this PDF flie.
The figure below is an example of the XC6365 series SOT-25 package.


For more details of the MSL, please refer to http://www.jedec.org/.

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