BU21077MUV Datasheet, PDF (7/16 Pages) Rohm – Capacitive Switch Controller IC

BU21077MUV
Power on Sequence
The power supply pin is only VDD. AVDD and DVDD are generated by built-in LDO, these are not necessary to supply
from external.
When the voltage level of RSTB change form low to High after VDD supplying, LDO is wakeup and DVDD voltage is
raised. And built-in power on reset (POR) circuit release the system reset and host interface is enable After DVDD
voltage reach the normal voltage range.
RSTB pin can not need to be controlled by host and connects to the VDD, because the BU21077MUV has POR circuit. If
the RSTB pin is connected to the VDD, the system reset is release automatically after VDD supplying.
VDD
Recommended Value of External Capacitors
C1 1.0uF Decoupling capacitor for VDD
C2 1.0uF Decoupling capacitor for DVDD
C3 2.2uF Decoupling capacitor for AVDD
VDD
AVDD
DVDD
C₁
BU21077MUV
C₃
C₂
VSS
GND
Figure 10. Arrangement of External Capacitors
VDD
VDD
RSTB
RSTB
DVDD
Power On
Reset
Figure 11. Power on Sequence (Controlled RSTB)
DVDD
Power On
Reset
Figure 12. Power on Sequence (VDD Shorted RSTB)
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TSZ02201-0L5L0F300820-1-2
14.Jul.2016 Rev.002