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XC9147/XC9148 Series

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NOTES ON USE

1) For the phenomenon of temporal and transitional voltage decrease or voltage increase, the IC may be damaged or deteriorated

if IC is used beyond the absolute MAX. specifications. Also, if used under out of the recommended operating range, the IC may

not operate normally or may cause deterioration.

2) Spike noise and ripple voltage arise in a switching regulator as with a DC/DC converter. These are greatly influenced by

external component selection, such as the coil inductance, capacitance values, and board layout of external components.

Once the design has been completed, verification with actual components should be done.

3) The DC/DC converter performance is greatly influenced by not only the ICs' characteristics, but also by those of the external

components. Care must be taken when selecting the external components. Especially for CL load capacitor, it is recommended

to use type B capacitors(JIS regulation) or X7R, X5R capacitors (EIA regulation).

4) When the CE pin is open, the IC will operate indefinitely. Therefore, the CE pin should not be open and should be set to a fixed

voltage. To prevent the IC and peripheral devices from malfunctioning due to pin-to-pin shorts, or to prevent the IC from being

damaged by external noise, etc., it is recommended that a resistor of 1MΩ or less be connected to the CE pin instead of

connecting it directly to the VBAT.

5) When the boost ratio is small, PWM control oscillates intermittently.

This may cause the switching frequency to drop below fOSC or increase output voltage ripple.

To suppress the ripple voltage, increase the capacitance value of the output capacitor and take measures

6) When connecting an external power supply to the output side, please use the XC9148 C/F/M/ L types.

When using the XC9148C/F/M/L type exclusion, depending on the bias conditions, the IC may break down and reverse flow to

the input side may occur.

7) Depending on the detection delay time of the current limit circuit, a coil current exceeding the limit current value ILIM may flow.

8) Under the following conditions, the current limit function may not operate.

XC9147 D/J types, XC9148 D/E/F/J/K/L types are used the integral latch method. In this case, the integral latch of the current

limit function and the latch stop by the short circuit protection function do not operate in these types

The boost ratio is small

When the boost ratio is small, the required duty is low and the on-time of the Nch driver FET on the low side is short.

If this on-time is shorter than the detection delay of the current limit circuit, the current limit function may not operate.

The boost ratio is high

When the boost ratio is high, the coil current may be limited below the current limit value due to the maximum duty ratio, on-

resistance, and DCR of the coil, and the current limit function may not operate.

9) The current limit function is a function that limits the current flowing through the Nch driver FET, and does not limit the current

flowing through the Pch synchronous switching FET.

Therefore, an overcurrent may flow in the parasitic diode of the Pch synchronous switching FET and the Pch synchronous

switching FET, and the IC may be destroyed.

10) XC9147 D/J types, XC9148 D/E/F/J/K/L types have short-circuit protection and integral latch function. If the output voltage

drops sharply due to an output short circuit, etc. The internal power supply of the IC may drop sharply by the circuit delay of the

VDD MAX circuit. As a result, the latch state of the short-circuit protection function may be reset and the latch stop may not be

maintained.