RAA230221 查看數據表（PDF） - Renesas Electronics
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RAA230221 Datasheet PDF : 32 Pages
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RAA23022x RAA23023x
Discharge Circuit
The device has discharge circuit in both CH1 and CH2. This enables a rapid discharge without an
external MOSFET. When an EN pin is changed from high level to low, each discharge switch in
VOUT pin is turned on and all capacitors which are connected to each output are rapidly
discharged through VOUT pin.
When VIN pin voltage becomes low level, discharge switches become off because there are no
voltage to keep them on. The control voltage of discharge switches is VREG, and the discharge
time of VREG capacitor is over 100ms when VIN voltage falls down, so even if EN pin is connected
to VIN pin, an output voltage can be discharged because VREG voltage level can keep the
discharge switches on.
Discharge time can be calculated by an equation below.
Vdc is a voltage after tdc(s).
CALL is sum of all capacitance which are connected to CH1 or CH2 output (output capacitor,
bypass capacitor around MCU, etc.).
Rondc is on resistance of discharge circuit.
VIN
VREG
CH1
Output
Control
Discharge
Control
CH2
Output
Control
Discharge
Control
VIN1
LX1
PGND1
VOUT1
Device A
Device B
Device C
VIN2
LX2
PGND2
VOUT2
Device D
Device E
Device F
Note : These dashed arrows are discharge line.
R18DS0017EJ0100 REV.1.00
Apr.21.2015
Page 18 of 30
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