Datasheet

LTC2635
22
2635fb
operation
Acknowledge
The Acknowledge (ACK) signal is used for handshaking
between the master and the slave. An ACK (active LOW)
generated by the slave lets the master know that the lat-
est byte of information was properly received. The ACK
related clock pulse is generated by the master. The master
releases the SDA line (HIGH) during the ACK clock pulse.
The slave-receiver must pull down the SDA bus line dur-
ing the ACK clock pulse so that it remains a stable LOW
during the HIGH period of this clock pulse. The LTC2635
responds to a write by a master in this manner but does
not acknowledge a read operation; in that case, SDA is
retained HIGH during the period of the ACK clock pulse.
Chip Address
The state of pins CA0, CA1 and CA2 (CA1 and CA2 are
only available on the QFN package) determines the slave
address of the part. These pins can be each set to any
one of three states: V
CC
, GND or float. This results in 27
(QFN Package) or 3 (MSOP Package) selectable addresses
for the part. The slave address assignments are shown
in Tables 1 and 2.
In addition to the address selected by the address pins,
the part also responds to a global address. This address
allows a common write to all LTC2635 parts to be ac-
complished using one 3-byte write transaction on the
I
2
C bus. The global address, listed at the end of Tables
1 and 2, is a 7-bit hardwired address not selectable by
CA0, CA1 or CA2. If another address is required, please
consult the factory.
The maximum capacitive load allowed on the address pins
(CA0, CA1 and CA2) is 10pF, as these pins are driven during
address detection to determine if they are floating.
Table 1. Slave Address Map (QFN Package)
CA2 CA1 CA0 A6 A5 A4 A3 A2 A1 A0
GND GND GND 0 0 1 0 0 0 0
GND GND FLOAT 0 0 1 0 0 0 1
GND GND V
CC
0 0 1 0 0 1 0
GND FLOAT GND 0 0 1 0 0 1 1
GND FLOAT FLOAT 0 1 0 0 0 0 0
GND FLOAT V
CC
0 1 0 0 0 0 1
GND V
CC
GND 0 1 0 0 0 1 0
GND V
CC
FLOAT 0 1 0 0 0 1 1
GND V
CC
V
CC
0 1 1 0 0 0 0
FLOAT GND GND 0 1 1 0 0 0 1
FLOAT GND FLOAT 0 1 1 0 0 1 0
FLOAT GND V
CC
0 1 1 0 0 1 1
FLOAT FLOAT GND 1 0 0 0 0 0 0
FLOAT FLOAT FLOAT 1 0 0 0 0 0 1
FLOAT FLOAT V
CC
1 0 0 0 0 1 0
FLOAT V
CC
GND 1 0 0 0 0 1 1
FLOAT V
CC
FLOAT 1 0 1 0 0 0 0
FLOAT V
CC
V
CC
1 0 1 0 0 0 1
V
CC
GND GND 1 0 1 0 0 1 0
V
CC
GND FLOAT 1 0 1 0 0 1 1
V
CC
GND V
CC
1 1 0 0 0 0 0
V
CC
FLOAT GND 1 1 0 0 0 0 1
V
CC
FLOAT FLOAT 1 1 0 0 0 1 0
V
CC
FLOAT V
CC
1 1 0 0 0 1 1
V
CC
V
CC
GND 1 1 1 0 0 0 0
V
CC
V
CC
FLOAT 1 1 1 0 0 0 1
V
CC
V
CC
V
CC
1 1 1 0 0 1 0
GLOBAL ADDRESS 1 1 1 0 0 1 1
Table 2. Slave Address Map (MSOP Package)
CA0 A6 A5 A4 A3 A2 A1 A0
GND 0 0 1 0 0 0 0
FLOAT 0 0 1 0 0 0 1
V
CC
0 0 1 0 0 1 0
GLOBAL ADDRESS 1 1 1 0 0 1 1