Cypress FM4 Series - BOOST Register

CHAPTER 7-2: VBAT Domain(A)
286 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
7.4 BOOST Register
BOOST Register sets the clock value of oscillation boost.
bit
7
6
5
4
3
2
1
0
Field
Reserved
BOOST1
BOOST0
Attribute
-
R/W
R/W
Initial value
-
1
1
The interface circuit type for this register is type 3.
[bit7:2] Reserved: Reserved bits
These bits read 0b000000.
In a write access to these bits, write 0b000000 to them.
[bit1:0] BOOST1, BOOST0: Oscillation boost time set bits
These bits set the number of clocks for oscillation boost.
Table 7-3 Settings of oscillation boost time
BOOST1
BOOST0
Oscillation boost time
1
1
500 ms [Initial value]
1
0
250 ms
0
1
125 ms
0
0
62.5 ms
After the oscillation boost time elapses, the oscillation boost operation is resumed, when a value different
from the BOOST register value retained by the VBAT power (backup power) is transferred by PWRITE.
Thus, if the oscillation boost operation is not required, transfer the same value as the BOOST register
value retained by the VBAT power (backup power).