CAT1161 Datasheet, PDF (10/12 Pages) Catalyst Semiconductor – Supervisory Circuits with I2C Serial CMOS EEPROM, Precision Reset Controller and Watchdog Timer

CAT1161/2
Immediate/Current Address Read
The CAT1161/2 address counter contains the address
of the last byte accessed, incremented by one. In other
words, if the last READ or WRITE access was to
address N, the READ immediately following would access
data from address N+1. For all devices, N=E=2047. The
counter will wrap around to Zero and continue to clock
out valid data for the 16K devices. After the CAT1161/
2 receives its slave address information (with the R/W bit
set to one), it issues an acknowledge, then transmits the
8-bit byte requested. The master device does not send
an acknowledge, but will generate a STOP condition.
Selective/Random Read
Selective/Random READ operations allow the Master
device to select at random any memory location for a
READ operation. The Master device first performs a
‘dummy’ write operation by sending the START condition,
slave address and byte addresses of the location it
wishes to read. After the CAT1161/2 acknowledges, the
Master device sends the START condition and the slave
address again, this time with the R/W bit set to one. The
CAT1161/2 then responds with its acknowledge and
sends the 8-bit byte requested. The master device does
not send an acknowledge but will generate a STOP
condition.
Sequential Read
The Sequential READ operation can be initiated by
either the Immediate Address READ or Selective READ
operations. After the CAT1161/2 sends the inital 8-bit
byte requested, the Master will responds with an
acknowledge which tells the device it requires more
data. The CAT1161/2 will continue to output an 8-bit
byte for each acknowledge, thus sending the STOP
condition.
The data being transmitted from the CAT1161/2 is
outputted sequentially with data from address N followed
by data from address N+1. The READ operation address
counter increments all of the CAT1161/2 address bits
so that the entire memory array can be read during one
operation. If more than E (where E=2047 for the
CAT1161/162) bytes are read out, the counter will ‘wrap
around’ and continue to clock out data bytes.
Manual Reset Operation
The CAT116x RESET or RESET pin can also be used
as a manual reset input.
Only the “active” edge of the manual reset input is
internally sensed. The positive edge is sensed if RESET
is used as a manual reset input and the negative edge
is sensed if RESET is used as a manual reset input.
An internal counter starts a 200 ms count. During this
time, the complementary reset output will be kept in the
active state. If the manual reset input is forced active for
more than 200 ms, the complementary reset output will
switch back to the non active state after the 200 ms
expired, regardless for how long the manual reset input
is forced active.
The embedded EEPROM is disabled as long as a reset
condition is maintained on any RESET pin. If the external
forced RESET/RESET is longer than internal controlled
time-out period, tPURST, the memory will not respond
with an acknowledge for any access as long as the
manual reset input is active.
Figure 10. Selective Read Timing
S
S
T
T
S
BUS ACTIVITY: ^A
SLAVE
BYTE
A _SLAVE
T
MASTER ^R ADDRESS
ADDRESS (n) ^R ADDRESS
O
T
T
P
SDA LINE S
S
P
A
A
C
C
K
K
A
N
C ^{DATA n}
O
K
A
C
K
Doc. No. 3002, Rev. D
10