
Clocks and Power Control
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
8-37
8.11.4
IRAMSTBY Control Register (VSRMCR)
This register contains control bits for enabling or disabling the IRAMSTBY supply detection circuit. There
are also four bits that indicate the failure detection. All four bits have the same function and are required
to improve the detection capability in extreme cases.
MSB
0
1
2
3
4
5
6
7
8
9
10
11121314
LSB
15
Field
—
LVSRS
VSRDE1
1 This bit is reserved on mask sets which implement bit 7 (ZOREG)
LVDRS ZOREG
—
PORESET
Unaffected
0
U
0_0000_0000
Addr
0x2F C290
U = Unaffected by reset
Figure 8-19. IRAMSTBY Control Register (VSRMCR)
Table 8-13. VSRMCR Bit Descriptions
Bits
Name
Description
0
—
Reserved
1:4
LVSRS
Loss of IRAMSTBY sticky. These status bits indicate whether a IRAMSTBY supply failure
occurred. In addition, when the power is turned on for the first time, IRAMSTBY rises and
these bits are set. The LVSRS bits are cleared by writing them to ones. A write of zero has
no effect on these bits.
0 No IRAMSTBY supply failure was detected
1 IRAMSTBY supply failure was detected
5
VSRDE1
1 Removed on all parts that have the ZOREG bit.
IRAMSTBY detector disable.
0 IRAMSTBY detection circuit is enabled
1 IRAMSTBY detection circuit is disabled
6
LVDRS
Loss of IRAMSTBY for DECRAM Sticky — The status bit, dedicated especially for the BBC
DECRAM, which indicates if there was IRAMSTBY supply failure. When the power is turned
on for the first time, IRAMSTBY rises also and the bits will be asserted. The LVDECRAM bit
can be cleared by writing ones to LVDECRAM. A write of zero has no effect on this bit. The
bit may be used by application software, to decide if there is need to load decompression
vocabularies during reset routine.
0 IRAMSTBY supply failure was not detected
1 IRAMSTBY supply failure was detected
NOTE: The LVDRS bit is provided as a convenience for indicating that the DECRAM has lost
power. It requires that the IRAMSTBY pins are connected to the same power supply. It
actually only monitors the IRAMSTBY supply.
7
ZOREG2
This bit indicates the status of the internal IRAMSTBY supply. This bit is cleared by writing
a 1 to it.
0 Internal IRAMSTBY zener regulator has not gone out of regulation
1 Internal IRAMSTBY zener regulator has gone out of regulation.
Note:
ZOREG may get set inadvertently if IRAMSTBY is not supplied with at least 150A.
8:15
—
Reserved