STK14C88-5LF35M Cypress Semiconductor Corp, STK14C88-5LF35M Datasheet - Page 11

• Manufacturer Part Number: STK14C88-5LF35M
• Manufacturer: Cypress Semiconductor Corp

Specifications of STK14C88-5LF35M

• Lead Free Status / RoHS Status: Compliant

Figure 11
automatic store operation. A charge storage capacitor having a
capacity of between 68 µF and 220 µF (±20%) rated at 6V should
be provided.
In system power mode, both V
+ 5V power supply without the 68 µF capacitor. In this mode, the
AutoStore function of the STK14C88 operates on the stored
system charge as power goes down. The user must, however,
guarantee that V
STORE cycle.
If an automatic STORE on power loss is not required, then V
can be tied to ground and + 5V applied to V
is the AutoStore Inhibit mode, in which the AutoStore function is
disabled. If the STK14C88 is operated in this configuration, refer-
ences to V
sheet. In this mode, STORE operations may be triggered
through software control or the HSB pin. To enable or disable
AutoStore using an I/O port pin, see
page 12.
To prevent unneeded STORE operations, automatic STOREs
and those initiated by externally driving HSB low are ignored
unless at least one write operation has taken place since the
most recent STORE or RECALL cycle. Software initiated
STORE cycles are performed regardless of whether a write
operation has taken place.
If the power supply drops faster than 20 ms/volt before V
reaches V
between V
of current between V
Figure 11. AutoStore Mode
AutoStore INHIBIT Mode
If an automatic STORE on power loss is not required, then V
can be tied to ground and system power applied to V
12). This is the AutoStore Inhibit mode, in which the AutoStore
function is disabled. If the STK14C88 is operated in this config-
uration, references to V
throughout this data sheet. In this mode, STORE operations may
be triggered through software control. It is not permissible to
change between these three options “on the fly.”
Document Number: 001-52038 Rev. *B
SWITCH
CC
CC
shows the proper connection of capacitors for
+
and the system supply to avoid momentary excess
should be changed to V
CC
, then a 2.2 ohm resistor should be inserted
does not drop below 3.6V during the 10 ms
cc
and V
1
16
CC
10k
CAP
Ω∗
CC
should be changed to V
.
and V
32
31
30
17
CAP
CAP
Preventing STORES
CAP
are connected to the
throughout this data
(Figure
CAP
12). This
(Figure
CAP
CC
CC
CC
on
Figure 12. AutoStore Inhibit Mode
HSB Operation
The STK14C88 provides the HSB pin for controlling and
acknowledging the STORE operations. The HSB pin can be
used to request a hardware STORE cycle. When the HSB pin is
driven low, the STK14C88 conditionally initiates a STORE
operation after t
write to the SRAM took place since the last STORE or RECALL
cycle. The HSB pin has a very resistive pull up and is internally
driven low to indicate a busy condition when the STORE
(initiated by any means) is in progress. Pull up this pin with an
external 10 Kohm resistor to V
SRAM read and write operations that are in progress when HSB
is driven low by any means are given time to complete before the
STORE operation is initiated. After HSB goes low, the
STK14C88 continues SRAM operations for t
t
is in progress when HSB is pulled low it is allowed a time,
tDELAY, to complete. However, any SRAM write cycles
requested after HSB goes low are inhibited until HSB returns
high.
The HSB pin can be used to synchronize multiple STK14C88s
while using a single larger capacitor. To operate in this mode, the
HSB pin should be connected together to the HSB pins from the
other STK14C88s. An external pull up resistor to + 5V is required
because HSB acts as an open drain pull down. The V
from the other STK14C88 parts can be tied together and share
a single capacitor. The capacitor size must be scaled by the
number of devices connected to it. When any one of the
STK14C88s detects a power loss and asserts HSB, the common
HSB pin causes all parts to request a STORE cycle (a STORE
takes place in those STK14C88s that are written since the last
nonvolatile cycle).
During any STORE operation, regardless of how it was initiated,
the STK14C88 continues to drive the HSB pin low, releasing it
only when the STORE is complete. Upon completion of the
STORE operation the STK14C88 remains disabled until the HSB
pin returns high.
If HSB is not used, leave it unconnected.
DELAY
, multiple SRAM read operations may take place. If a write
DELAY
; an actual STORE cycle only begins if a
1
16
CAP
if HSB is used as a driver.
17
32
31
30
STK14C88
DELAY
Page 11 of 19
. During
CAP
pins
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