19/43

XC9147/XC9148

Series

■

OPERATIONAL EXPLANATION

＜

Current Limit / Short Circuit Protection / Integral Latch＞

The current limit function of this IC monitors the current flowing in the Nch driver (=coil current) for each switching cycle,

and when the current flowing through the Nch driver FET reached the current limit value ILIM (TYP. 2.42A @ VOUT (T)=5.0V), it will

be in the overcurrent detection state.

When the overcurrent detection state occurs, the Nch driver FET is turned off and the detection state is maintained during this

switching cycle. If the current flowing to the Nch driver FET is less than the current limit value ILIM in the next switching cycle, the

overcurrent detection state is released.

If the overcurrent detection state is continued or if there is a significant drop in output voltage, the short circuit protection

function and integral latch function are activated depending on the type.

The details of the operation for each type are as follows.

No short circuit protection/integral latch: XC9147 A/G types ,XC9148 A/B/C/G/H/M types

①

If the current flowing in the Nch driver FET reaches the current limit value ILIM, it will be in the overcurrent detection state.

The Nch driver FET turns off and remains off during this switching cycle.

②

In the next switching cycle, the Nch driver FET turns on.

If the overcurrent state continues and the current flowing to the Nch driver FET reaches the current limit value ILIM,

the overcurrent detection state is maintained.

③

If overcurrent state continues, ① and ② are repeated.

RLoad

VOUT

Coil

Current

0Ω

0A

ILIM

Current Limit State

Normal operation

VOUT(T)

0V

VBAT

IOUT

0A