LTC2309 Linear Technology Corporation, LTC2309 Datasheet - Page 14

• Manufacturer Part Number: LTC2309
• Description: 12-Bit SAR ADC
• Manufacturer: Linear Technology Corporation

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LTC2309
The data output stream is 16 bits long and is shifted
out on the falling edges of SCL (see Figure 8a). The
fi rst bit is the MSB and the 12th bit is the LSB of the
conversion result. The remaining four bits are zero.
Figures 14 and 15 are the transfer characteristics for
the bipolar and unipolar modes. Data is output on the
SDA line in 2’s complement format for bipolar readings
or in straight binary for unipolar readings.
APPLICATIONS INFORMATION
14
SDA
SCL
START BY
SDA
MASTER
SCL
START BY
MASTER
A6
1
A6
1
A5
2
A5
2
A4
3
A4
3
ADDRESS FRAME
A3
4
ADDRESS FRAME
A3
4
Figure 8a. Timing Diagram for Reading from the LTC2309
A2
Figure 8b. Timing Diagram for Writing to the LTC2309
5
A2
5
A1
6
A1
6
(CONTINUED)
(CONTINUED)
A0
7
A0
7
R/W
8
SDA
SCL
R/W
8
ACK BY
9
ACK BY
• • •
• • •
ADC
ADC
9
B11 B10
B3
1
1
Input Data Format
When the LTC2309 is addressed for a write operation,
it acknowledges by pulling SDA low during the low
period before the 9th cycle and acts as a receiver. The
master/transmitter can then send 1 byte to program the
device. The input byte consists of the 6-bit D
followed by two bits that are ignored by the ADC and
are considered don’t cares (X) (see Figure 8b). The
input bits are latched on the rising edge of SCL during
the write operation.
S/D
1
B2
2
2
LEAST SIGNIFICANT DATA BYTE
MOST SIGNIFICANT DATA BYTE
O/S
2
B9
B1
3
3
D
S1
IN
3
WRITE 1 BYTE
READ 1 BYTE
WORD
B8
B0
READ 1 BYTE
4
4
S0
4
B7
5
5
UNI
5
B6
6
6
SLP
6
B5
7
7
X
7
B4
8
8
X
8
MASTER
NAK BY
MASTER
ACK BY
9
9
ACK BY
9
ADC
• • •
• • •
2309 F08b
2309 F08a
CONVERSION
CONVERSION
BY MASTER
INITIATED
STOP BY
INITIATED
MASTER
STOP
IN
word
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