M40Z300MH STMICROELECTRONICS [STMicroelectronics], M40Z300MH Datasheet - Page 8

• Manufacturer Part Number: M40Z300MH
• Description: NVRAM CONTROLLER for up to EIGHT LPSRAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M40Z300, M40Z300W
Table 7. Power Down/Up AC Characteristics
(T
Note: 1. V
BATTERY LOW PIN
The M40Z300/W automatically performs battery
voltage monitoring upon power-up, and at factory-
programmed time intervals of at least 24 hours.
The Battery Low (BL) pin will be asserted if the
battery voltage is found to be less than approxi-
mately 2.5V. The BL pin will remain asserted until
completion of battery replacement and subse-
quent battery low monitoring tests, either during
the next power-up sequence or the next scheduled
24-hour interval.
If a battery low is generated during a power-up se-
quence, this indicates that the battery is below
2.5V and may not be able to maintain data integrity
in the SRAM. Data should be considered suspect,
and verified as correct. A fresh battery should be
installed.
8/16
A
Symbol
t
= 0 to 70°C)
t
t
FB
t
t
t
t
F
WPT
2. V
EDH
t
CER
REC
t
EDL
t
RB
AS
R
(1)
(2)
V
PFD
CC
PFD
passes V
(max) to V
(min) to V
V
V
V
Chip Enable Propagation Delay Low
Chip Enable Propagation Delay High
A, B set up to E
Chip Enable Recovery
V
Write Protect Time
V
PFD
PFD
PFD
PFD
SS
to V
PFD
(min) to V
(max) to V
(min) to V
(max) to RST High
SS
PFD
(min)..
PFD
fall time of less than tFB may cause corruption of RAM data.
(min) fall time of less than tF may result in deselection/write protection not occurring until 200 µs after
(min) V
PFD
SS
PFD
V
(max) V
CC
CC
(min) V
Fall Time
Rise Time
Parameter
CC
CC
Rise Time
Fall Time
If a battery low indication is generated during the
24-hour interval check, this indicates that the bat-
tery is near end of life. However, data is not com-
promised due to the fact that a nominal V
supplied. In order to insure data integrity during
subsequent periods of battery back-up mode, the
battery should be replaced. SNAPHAT top should
be replaced with valid V
The M40Z300/W only monitors the battery when a
nominal V
cations which require extensive durations in the
battery back-up mode should be powered-up peri-
odically (at least once every few months) in order
for this technique to be beneficial. Additionally, if a
battery low is indicated, data integrity should be
verified upon power-up via a checksum or other
technique. The BL pin is an open drain output and
an appropriate pull-up resistor to V
chosen to control the rise time.
M40Z300
M40Z300W
M40Z300
M40Z300W
M40Z300
M40Z300W
CC
is applied to the device. Thus appli-
Min
300
150
10
40
40
40
40
0
1
CC
applied to the device.
Max
120
120
150
250
12
20
10
20
CC
should be
Unit
ms
ms
µs
µs
ns
ns
ns
ns
ns
µs
µs
µs
µs
CC
is