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XC9147/XC9148

Series

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OPERATIONAL EXPLANATION

＜

Thermal shutdown＞

The junction temperature is monitored to protect the IC from thermal destruction.

When the junction temperature reaches the thermal shutdown detection temperature TTSD (TYP. 150°C), the thermal shutdown

activated, and the Nch driver FET and Pch synchronous switching FET are turned off, and the output voltage drops. When the

chip temperature drops to the thermal shutdown release temperature TTSD-THYS (TYP. 125°C) by stopping the current supply, the

output voltage is turned on by the start-up mode, and then normal operation starts.

In order to suppress the current consumption at the light load, XC9148 series stops the thermal shutdown function when the

output current is small at the PFM control.

＜

UVLO＞

XC9147 G/J types and XC9148 G/H/M/J/K/L types have UVLO function.

If BAT voltage becomes equal or less than VUVLO_R (TYP.1.60V)- VUVLO_HYS (TYP.0.15V), UVLO Detect Delay: tDF (TYP. 1.2MHz:

200μs, 3.0MHz: 100μs) continues, then UVLO becomes active.

When UVLO detection state is reached, the switching operation is stopped and Nch driver FET and Pch synchronous switching

FET are turned off.

If BAT voltage is higher than VUVLO_R, the output voltage is raised by the start-up mode, and then normal operation is performed.

The consumption current of the products with UVLO function is slightly higher than the products without UVLO function due to

the operation of UVLO function

＜

CL Discharge＞

A/D/G/J types can discharge the electric charge at the output capacitor (CL) quickly during standby mode(CE=”L”) via the Nch

FET located between VOUT and GND.

Electric charge at the output capacitor (CL) is quickly discharged so that it may avoid application malfunction during standby

mode.

Discharge time of the output capacitor (CL) is set by the CL discharge resistance (RDCHG) and the output capacitor (CL). By setting

time constant of a CL discharge resistance value [RDCHG] and an output capacitor value (CL) as τ(τ＝CL×RDCHG), discharge time

can be the calculated by the following formulas.

However, the CL discharge resistance [RDCHG] is depends on the VBAT or VOUT. We recommend that you fully check actual

performance.

V = VOUT(T) × e -t /τ

t = τ× ln (VOUT(T) / V)

V : Output voltage after discharge

VOUT(T) : Target voltage

t : Discharge time

τ

: CL × RDCHG

CL : Capacitance of Output capacitor (CL)

RDCHG : CL Discharge resistance, it depends on the VBAT or VOUT