Datasheet

LTC2309
16
2309fd
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
IN
word
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.
After power-up, the ADC initiates an internal reset
cycle which sets the D
IN
word to all 0s (S/D = O/S =
S0 = S1 = UNI = SLP = 0). A write operation may be
performed if the default state of the ADC’s configuration
is not desired. Otherwise, the ADC must be properly
addressed and followed by a STOP condition to initiate
a conversion.
Initiating a New Conversion
The LTC2309 awakens from either nap or sleep when
properly addressed for a read/write operation. A STOP
command may then be issued after performing the
read/write operation to trigger a new conversion.
Issuing a STOP command after the 8th SCL clock pulse
of the address frame and before the completion of a
Table 2. Address Assignment
AD1 AD0 ADDRESS
LOW LOW 0001000
LOW Float 0001001
LOW HIGH 0001010
Float HIGH 0001011
Float Float 0011000
Float LOW 0011001
HIGH LOW 0011010
HIGH Float 0011011
HIGH HIGH 0101000
1 2
A6SDA
START BY
MASTER
ACK BY
ADC
ACK BY
ADC
CONVERSION
INITIATED
STOP BY
MASTER
SCL
A5 A4 A3 A2 A1 A0 R/W
3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
2309 F08b
S/D O/S
WRITE 1 BYTE
S1 S0 UNI
D
IN
WORD
SLP X X
ADDRESS FRAME
Figure 8b. Timing Diagram for Writing to the LTC2309
AppLICAtIOns InFORMAtIOn
read/write operation will also initiate new conversion,
but the output result may not be valid due to lack of
adequate acquisition time (see Acquisition section).
LTC2309 Address
The LTC2309 has two address pins (AD0 and AD1) that
may be tied HIGH, LOW, or left floating to enable one
of 9 possible addresses (see Table 2).
In addition to the configurable addresses listed in
Table 2, the LTC2309 also contains a global address
(1101011) which may be used for synchronizing mul-
tiple LTC2309s or other I
2
C LTC230X SAR ADCs (see
Synchronizing Multiple LTC2309s with Global Address
Call section).