MAX1069 Datasheet, PDF (14/20 Pages) Maxim Integrated Products – 58.6ksps, 14-Bit, 2-Wire Serial ADC

58.6ksps, 14-Bit, 2-Wire Serial ADC
in a 14-Pin TSSOP
S
Sr
P
SDA
SCL
Figure 7. START and STOP Conditions
S
SDA
SCL
1
2
NOT ACKNOWLEDGE
ACKNOWLEDGE
8
9
Figure 8. Acknowledge Bits
of a STOP condition to leave the bus active and in its
current timing mode (see the HS-Mode section).
Acknowledge Bits
Successful data transfers are acknowledged with an
acknowledge bit (A) or a not-acknowledge bit (A). Both
the master and the MAX1069 (slave) generate acknowl-
edge bits. To generate an acknowledge, the receiving
device must pull SDA low before the rising edge of the
acknowledge-related clock pulse (ninth pulse) and
keep it low during the high period of the clock pulse
(Figure 8). To generate a not acknowledge, the receiver
allows SDA to be pulled high before the rising edge of
the acknowledge-related clock pulse and leaves it high
during the high period of the clock pulse.
Monitoring the acknowledge bits allows for detection of
unsuccessful data transfers. An unsuccessful data
transfer happens if a receiving device is busy or if a
system fault has occurred. In the event of an unsuc-
cessful data transfer, the master should reattempt com-
munication at a later time.
Slave Address
A master initiates communication with a slave device by
issuing a START condition followed by a slave address
byte. As shown in Figure 9, the slave address byte con-
sists of 7 address bits and a read/write bit (R/W). When
idle, the MAX1069 continuously waits for a START con-
dition followed by its slave address. When the
MAX1069 recognizes its slave address, it acquires the
analog input signal and prepares for conversion. The
first three bits (MSBs) of the slave address have been
factory programmed and are always 011. Connecting
ADD3–ADD0 to DV_DD or DGND, programs the last four
bits (LSBs) of the slave address high or low.
Since the MAX1069 does not require setup or configu-
ration, the least significant bit (LSB) of the address byte
(R/W) controls power-down. In external reference mode
(REFADJ = AV_DD), R/W is a don’t care. In internal refer-
ence mode, setting R/W = 1 places the device in nor-
mal operation and setting R/W = 0 powers down the
internal reference following the conversion (see the
Internal Reference Shutdown section).
After receiving the address, the MAX1069 (slave)
issues an acknowledge by pulling SDA low for one
clock cycle.
Bus Timing
At power-up, the MAX1069 bus timing defaults to fast
mode (F/S-mode), allowing conversion rates up to
19ksps. The MAX1069 must operate in high-speed
mode (HS-mode) to achieve conversion rates up to
58.6ksps. Figure 1 shows the bus timing for the
MAX1069 2-wire interface.
HS-Mode
At power-up, the MAX1069 bus timing is set for F/S-
mode. The master selects HS-mode by addressing all
devices on the bus with the HS-mode master code 0000
1XXX (X = don’t care). After successfully receiving the
HS-mode master code, the MAX1069 issues a not
acknowledge allowing SDA to be pulled high for one
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