XC8101_12 Datasheet, PDF (7/37 Pages) Torex Semiconductor – High Side Load Switch with Low Supply Current

XC8101
Series
■OPERATIONAL EXPLANATION
<CE Pin>
The XC8101 enables an output P-channel MOSFET switch and the IC internal circuitry to turn off by the signal to the CE pin. In
the shutdown mode, the V_OUT pin will be pulled down to the V_SS by the C_L auto-discharge function.
The output voltage becomes unstable when the CE pin is opened. If the input voltage to the CE pin is within the specified
threshold voltages, the logic is fixed and the XC8101 will operate normally. However, supply current may increase as a result
of the shoot-through current of internal circuitry when the medium level voltage is input to the CE pin.
＜Input Capacitor＞
The XC8101 works well without an output capacitor （CL）. However, an output capacitor such as a bypass capacitor is tied up
to the output side of the IC, input voltage ringing may occur when the IC is turned on. In order to reduce the ringing, an input
capacitor with the value of 1μF or more is requested to attach between V_IN pin and V_SS pin. The capacitor should be tied and
placed as close as the IC.
<CL Auto-Discharge Function>
The XC8101A contains a C_L auto-discharge resistor and an N-channel transistor between the VOUT pin and the VSS pin. The
XC8101A quickly discharge the electric charge in the output capacitor (C_L) when a low signal to the CE pin is input to turn off a
whole IC circuit. . The C_L auto-discharge resistance is set at 900Ω (V_OUT=4.0V TYP. @ V_IN=4.0). Discharge time of the output
capacitor (C_L) is determined by a CL auto-discharge resistor value (R_DCHG) and an output capacitor value. Time constant τ is
defined as (τ = C x R_DCHG). Output voltage after starting discharge can be calculated by the following formula.
V = VOUT x e ^–t/τ, or t=τIn (VOUT / V)
V: Output voltage after starting discharge
VOUT: Output voltage
t: Discharge time
τ: Output discharge resistor value Rdischg×Output capacitor (CL) value C
<Current Limiter, Short-Circuit Protection>
The XC8101 series contains a constant current limiter and foldback current circuitry. The constant current limiter operates to
limit output current and the foldback current circuitry operates as short circuit protection for the output pin.
When the load current reaches the limit current, the constant current limiter operates and the output voltage drops. The output
voltage further, then the foldback current circuitry operates to decrease the output current. When the output pin is short-circuited
to the ground, the output current drops and maintains a flow about 30mA.
■NOTES ON USE
1. Please use this IC within the stated absolute maximum ratings. Operation beyond these limits may cause degrading or
permanent damage to the device.
2. The X8101 goes into an undefined operation when the CE pin is left open. The CE pin shall be tied to low or high level.
3. V_OUT pin voltage should not be applied beyond the V_IN pin voltage. The IC may get damage due to the reverse current
toward the V_IN pin.
7/37