Rainbow Electronics MAX1289 - Manual (Page 9)

MAX1286–MAX1289
150ksps, 12-Bit, 2-Channel Single-Ended, and
1-Channel True-Differential ADCs in SOT23
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Analog Input Protection
Internal protection diodes that clamp the analog input to
V
DD and GND allow the analog input pins to swing from
GND - 0.3V to V DD + 0.3V without damage. Both inputs
must not exceed V DD by more than 50mV or be lower
than GND by more than 50mV for accurate conversions.
If an off-channel analog input voltage exceeds the
supplies, limit the input current to 2mA.
Internal Clock
The MAX1286–MAX1289 operate from an internal oscilla-
tor, which is accurate within 10% of the 4MHz specified
clock rate. This results in a worst-case conversion time of
3.7µs. The internal clock releases the system micro-
processor from running the SAR conversion clock and
allows the conversion results to be read back at the
processor’s convenience, at any clock rate from 0 to
8MHz.
CNVST
SCLK
DOUT
t ACQ
t CONV
SAMPLING INSTANT
4 1 8 12
B11
MSB
B10 B9 B8 B7 B6 B5 B4 B3 B2 B1
B0
LSB
HIGH-Z
HIGH-Z
CNVST
SCLK
DOUT
t ACQ
t CONV
SAMPLING INSTANT
4 1 8 12
B11
MSB
B10 B9 B8 B7 B6 B5 B4 B3 B2 B1
B0
LSB
HIGH-Z
HIGH-Z
Figure 5b. Single Conversion AIN2 vs. GND (MAX1286/MAX1287), Bipolar Mode AIN+ vs. AIN- (MAX1288/MAX1289)
Figure 5a. Single Conversion AIN1 vs. GND (MAX1286/MAX1287), Unipolar Mode AIN+ vs. AIN- (MAX1288/MAX1289)