(FRAM access || FRPWR =1)
Reset (PUC)
(LPM Entry)
(FRPWR =0)
ACTIVE
FRAM PWR = ON
DEVICE PWR = AM
(LPM Entry)
(LPM Exit && FRPW
R =1)
(LPM Exit && FRPW
R=0)
INACTIVE
FRAM PWR = OFF
DEVICE PWR = AM
INACTIVE
FRAM PWR = OFF
DEVICE PWR = LPM
FRAM Cache
303
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
FRAM Controller A (FRCTL_A)
Table 8-2. FRAM Power Mode Transition (continued)
Power Control Source
FRAM Power State
(Start)
FRAM Power State
(End)
Device Power Mode
FRPWR Bit
FRAM Access
LPM0, LPM1, LPM2,
LPM3, or LPM4
→
AM
1
No
INACTIVE
ACTIVE
LPM0, LPM1, LPM2,
LPM3, or LPM4
→
AM
0
No
INACTIVE
INACTIVE
shows the flow of the FRAM power transitions.
Figure 8-2. FRAM Power Control Diagram
8.5
FRAM Cache
The FRAM controller A (FRCTL_A) has a cache that contains four 64-bit lines. One of the 64-bit lines is
preloaded during one access cycle and the cache can keep up to 32 bytes (4 × 64 bit) from the latest
accesses to FRAM memory. When an FRAM read is requested, the FRAM controller A (FRCTL_A) first
checks cache. If the requested data is found in cache (a cache hit), then the data is read from the cache
and no physical FRAM access occurs. In this case, no wait state is required and the data is accessed at
the full system bus speed.