Cypress FM4 Series - Page 305

CHAPTER 7-3: VBAT Domain(B)
FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E 305
 Interface circuit type 2
Figure 2-3 Configuration of Interface Circuit Type 2
Use this circuit type if the register has to retain data even when the VCC power supply is off.
Table 2-3 Behavior of Register of Interface Circuit Type 2
Behavior of Register/Buffer
Initialization of register
Initialization of register by the power-on signal of the VBAT Domain
Initialization of buffer
Initialization of register by the reset signal of the Always-on Domain
For reset factors, see the chapter “RTC Count Block”.
Bus read
Data in the buffer is read to the bus.
Bus write
Data is written to the buffer.
Recall operation
Data is transferred from the register to the buffer.
Save operation
Data is transferred from the buffer to the register.
 Interface circuit type 3
Figure 2-4 Configuration of Interface Circuit Type 3
Use this circuit type if the register has to retain data even when the VCC power supply is off.
Table 2-4 Behavior of Register of Interface Circuit Type 3
Behavior of Register/Buffer
Initialization of register
Initialization of register by the power-on signal of the VBAT Domain
Initialization of buffer
Initialization of register by the reset signal of the Always-on Domain
Initialization of register by RTC reset.
Bus read
Data in the buffer is read to the bus.
Bus write
Data is written to the buffer.
Recall operation
Data is transferred from the register to the buffer.
Save operation
Data is transferred from the buffer to the register.
Always-on Domain
FF
(Buffer)
Internal bus
Transfer
control
32KHz
VBAT Domain
FF
(Register)
Peripheral
function
Level shifter
Isolator
VBAT Domain
FF
(Register)
Peripheral
function
Level shifter
Isolator
Always-on Domain
FF (Buffer)
Internal bus
Transfer
control
PCLK2