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MAX7347ATE+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P29
MAX7347/MAX7348/MAX7349
2-Wire Interfaced Low-EMI Key Switch
and Sounder Controllers
_______________________________________________________________________________________ 7
STOP (P) condition by transitioning SDA from low to
high while SCL is high. The bus is then free for another
transmission.
Bit Transfer
One data bit is transferred during each clock pulse
(Figure 4). The data on SDA must remain stable while
SCL is high.
Acknowledge
The acknowledge bit is a clocked 9th bit (Figure 5),
which the recipient uses to handshake receipt of each
byte of data. Thus, each byte transferred effectively
requires 9 bits. The master generates the 9th clock
pulse, and the recipient pulls down SDA during the
acknowledge clock pulse, so the SDA line is stable low
during the high period of the clock pulse. When the
master is transmitting to the MAX7347/MAX7348/
MAX7349, the MAX7347/MAX7348/MAX7349 generate
the acknowledge bit because the MAX7347/MAX7348/
MAX7349 are the recipients. When the MAX7347/
MAX7348/MAX7349 are transmitting to the master, the
master generates the acknowledge bit because the
master is the recipient.
KEY
0
KEY
8
KEY
16
KEY
24
KEY
32
KEY
40
KEY
48
KEY
56
KEY
1
KEY
9
KEY
17
KEY
25
KEY
33
KEY
41
KEY
49
KEY
57
KEY
2
KEY
10
KEY
18
KEY
26
KEY
34
KEY
42
KEY
50
KEY
58
KEY
3
KEY
11
KEY
19
KEY
27
KEY
35
KEY
43
KEY
51
KEY
59
KEY
4
KEY
12
KEY
20
KEY
28
KEY
36
KEY
44
KEY
52
KEY
60
KEY
5
KEY
13
KEY
21
KEY
29
KEY
37
KEY
45
KEY
53
KEY
61
KEY
6
KEY
14
KEY
22
KEY
30
KEY
38
KEY
46
KEY
54
KEY
62
KEY
7
KEY
15
KEY
23
KEY
31
KEY
39
KEY
47
KEY
55
KEY
63
ROW0
ROW1
ROW2
ROW3
ROW4
ROW5
ROW6
ROW7
COL0
COL1
COL2/PORT2
COL3/PORT3*
COL4/PORT4*
COL5/PORT5**
COL6/PORT6**
COL7/PORT7**
*MAX7348 AND
MAX7349 ONLY.
**MAX7349 ONLY.
Figure 1. Keys Order
MAX7347/MAX7348/MAX7349
2-Wire Interfaced Low-EMI Key Switch
and Sounder Controllers
8 _______________________________________________________________________________________
SDA
SCL
t
HD, STA
t
LOW
t
HIGH
t
R
t
F
t
SU, DAT
t
SU, STA
t
SU, STO
t
BUF
t
HD, STA
t
HD, DAT
START
CONDITION
STOP
CONDITION
START
CONDITION
REPEATED
START CONDITION
Figure 2. 2-Wire Serial Interface Timing Details
SDA
SCL
START
CONDITION
STOP
CONDITION
S
P
Figure 3. Start and Stop Conditions
SDA
SCL
DATA LINE STABLE;
DATA VALID
CHANGE OF DATA
ALLOWED
Figure 4. Bit Transfer
MAX7347/MAX7348/MAX7349
2-Wire Interfaced Low-EMI Key Switch
and Sounder Controllers
_______________________________________________________________________________________ 9
Slave Addresses
The MAX7347/MAX7348/MAX7349 have two 7-bit long
slave addresses (Figure 6). The bit following a 7-bit
slave address is the R/W bit, which is low for a write
command and high for a read command.
The first 4 bits (MSBs) of the MAX7347/MAX7348/
MAX7349 slave addresses are always 0111. Slave
address bits A3, A2, and A1 correspond, by the matrix
in Table 3, to the states of the device address input
AD0, and A0 corresponds to the R/W bit. MAX7347/
MAX7348/MAX7349 use two slave addresses, one for
the main key-scan controller, and one for the sounder
controller. The AD0 input can be connected to any of
four signals: GND, V+, SDA, or SCL, giving four possible
slave address pairs, allowing up to four MAX7348/
MAX7349 devices to share the bus. Only one MAX7347
can share the bus. The MAX7347 AD0 input is internally
connected to GND.
The MAX7347/MAX7348/MAX7349 monitor the bus
continuously, waiting for a START condition followed by
its slave address. When MAX7347/MAX7348/MAX7349
recognize their slave address, they acknowledge and
are then ready for continued communication.
PIN COL0 COL1 COL2/PORT2 COL3/PORT3 COL4/PORT4 COL5/PORT5 COL6/PORT6 COL7/PORT7
ROW0 KEY 0 KEY 8 KEY 16 KEY 24 KEY 32 KEY 40 KEY 48 KEY 56
ROW1 KEY 1 KEY 9 KEY 17 KEY 25 KEY 33 KEY 41 KEY 49 KEY 57
ROW2 KEY 2 KEY 10 KEY 18 KEY 26 KEY 34 KEY 42 KEY 50 KEY 58
ROW3 KEY 3 KEY 11 KEY 19 KEY 27 KEY 35 KEY 43 KEY 51 KEY 59
ROW4 KEY 4 KEY 12 KEY 20 KEY 28 KEY 36 KEY 44 KEY 52 KEY 60
ROW5 KEY 5 KEY 13 KEY 21 KEY 29 KEY 37 KEY 45 KEY 53 KEY 61
ROW6 KEY 6 KEY 14 KEY 22 KEY 30 KEY 38 KEY 46 KEY 54 KEY 62
ROW7 KEY 7 KEY 15 KEY 23 KEY 31 KEY 39 KEY 47 KEY 55 KEY 63
Table 2. Key-Switch Mapping
DEVICE ADDRESS
PIN AD0
A7 A6 A5 A4 A3 A2 A1 A0 R/W
FUNCTION
0 Key-scan controller write
0
1 Key-scan controller read
0 Sounder controller write
GND 011100
1
1 Sounder controller read
0 Key-scan controller write
0
1 Key-scan controller read
0 Sounder controller write
V+ 011101
1
1 Sounder controller read
0 Key-scan controller write
0
1 Key-scan controller read
0 Sounder controller write
SDA 011110
1
1 Sounder controller read
0 Key-scan controller write
0
1 Key-scan controller read
0 Sounder controller write
SCL 011111
1
1 Sounder controller read
Table 3. 2-Wire Interface Address Map
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P29

MAX7347ATE+T

Mfr. #:
Buy MAX7347ATE+T
Manufacturer:
Maxim Integrated
Description:
Interface - Specialized Low-EMI Key Switch & Sounder Controller
Lifecycle:
New from this manufacturer.
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