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XCL201/XCL202

Series

■

NOTE ON USE

④

Limit > #ms

⑤

③

②

①

Duty

1. The XCL201/XCL202 series is designed for use with ceramic output capacitors. If, however, the potential difference is too large between

the input voltage and the output voltage, a ceramic capacitor may fail to absorb the resulting high switching energy and oscillation could

occur on the output. If the input-output potential difference is large, connect an electrolytic capacitor in parallel to compensate for

insufficient capacitance.

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. Depending on the input-output voltage differential, or load current, some pulses may be skipped, and the ripple voltage may increase.

4. When the difference between input and output is large in PWM control, very narrow pulses will be outputted, and there is the possibility that

some cycles may be skipped completely.

5. When the difference between input and output is small, and the load current is heavy, very wide pulses will be outputted and there is the

possibility that some cycles may be skipped completely.

6. With 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 operation, 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:

L: Coil Inductance Value

7. When the peak current which exceeds limit current flows within the specified time, the built-in P-ch driver transistor turns off. During the

time until it detects limit current and before the built-in transistor can be turned off, the current for limit current flows; therefore, care must be

taken when selecting the rating for the external components such as a coil.

9. Depending on the state of the PC Board, latch time may become longer and latch operation may not work. In order to avoid the effect of

noise, the board should be laid out so that input capacitors are placed as close to the IC as possible.

10. Use of the IC at voltages below the recommended voltage range may lead to instability.

11. This IC should be used within the stated absolute maximum ratings in order to prevent damage to the device.

12. When the IC is used in high temperature, output voltage may increase up to input voltage level at no load because of the leak current of

the driver transistor.

13. The current limit is set to 1000mA (MAX.) at typical. However, the current of 1000mA or more may flow.

input voltage will occur at both ends of a coil. For this, the time rate of coil current becomes large. By contrast, when N-ch MOSFET is

rate of coil current becomes quite small. According to the repetition of this operation, and the delay time of the circuit, coil current will be

converged on a certain current value, exceeding the amount of current, which is supposed to be limited originally. Even in this case,

however, after the over current state continues for several ms, the circuit will be latched. A coil should be used within the stated absolute

maximum rating in order to prevent damage to the device.

①

②

③

Because of no potential difference at both ends of the coil, the time rate of coil current becomes quite small.

④

Lx oscillates very narrow pulses by the current limit for several ms.

⑤

The circuit is latched, stopping its operation.