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XC9515

Series

■NOTES ON USE (Continued)

7.

Driving current below the minimum operating voltage may lead malfunction to the UVLO circuit because of the noise.

8.

Depending on the PC board condition, the latch function may be released from limit current detection state and the latch

time may extend or fail to reach the latch operation. Please locate the input capacitance as close to the IC as possible.

9.

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.

10. With the DC/DC converter block of the IC, the peak current of the coil is controlled by the current limit circuit. Since the

peak current increases when dropout voltage or load current is high, current limit starts operating, and this can lead to

instability. When peak current becomes high, please adjust the coil inductance value and fully check the circuit operation.

In addition, please calculate the peak current according to the following formula:

11. When the load current is light in PWM control, very narrow pulses will be outputted, and there is the possibility that some

cycles may be skipped completely.

there is the possibility that some cycles may be skipped completely.

13. If the power input pin voltage is assumed to decrease rapidly (ex. from 6.0V to 0V) at the release of the operation

although delay capacitance (Cd) pin is connected, please connect an Shottky barrier diode between the power input

15. The delay time of the voltage detector block in heavy load may extend because of the noise of the DC/DC block.

Precipitous and large voltage fluctuation at the power input pin may cause malfunction of the IC.

16. Use of the IC at voltages below the minimum operating voltage may lead the output voltage drop before achieving over

current limit.

17. When P_VDD1 and P_VDD2 power supply pins and EN1 and EN2 enable pins are in undefined states, the latch

protection circuit may not be reset so that the IC operation does not start correctly. Power supply and enable pins

（

EN1,EN2） should be grounded before starting the IC operation.

【

Undefined state conditions for each pin】

nanoseconds.

●

Instruction on Pattern Layout

1.

2.

Please mount each external component as close to the IC as possible.

3.

Wire external components as close to the IC as possible and use thick, short connecting traces to reduce the circuit

impedance.

at the time of switching may result in instability of the DC/DC converter.