MAX1332 Datasheet, PDF (17/25 Pages) Maxim Integrated Products – 3Msps/2Msps, 5V/3V, 2-Channel, True-Differential 12-Bit ADCs

3Msps/2Msps, 5V/3V, 2-Channel, True-
Differential 12-Bit ADCs
CNVST
SCLK
DOUT
MODE
1ST 8-BIT TRANSFER
EXECUTE PARTIAL POWER-DOWN TWICE
2ND 8-BIT TRANSFER
1ST SCLK RISING EDGE
1ST SCLK RISING EDGE
0
0
0 D11 D10 D9 D8 D7
0
0
0
0
0
0
0
0
NORMAL
PPD
RECOVERY
FPD
Figure 8. SPI Interface—Full Power-Down
FS = V_REF
FFF
ZS = 0
FFE
1 LSB = ^VREF
4096
FFD
FFC
FFB
FULL-SCALE
TRANSITION
004
003
002
001
000
01234
FS
FS - 1.5 LSB
DIFFERENTIAL INPUT VOLTAGE (LSB)
Figure 9. Unipolar Transfer Function
+FS = ^VREF
7FF
2
ZS = 0
7FE
-FS = ^-VREF
2
001
1 LSB = ^VREF
4096
000
FFF
FFE
FULL-SCALE
TRANSITION
801
800
-FS
0
+FS
-FS + 0.5 LSB
+FS - 1.5 LSB
DIFFERENTIAL INPUT VOLTAGE (LSB)
Figure 10. Bipolar Transfer Function
Another way of entering the full power-down mode is
using the SHDN input. Drive SHDN to a logic low to put
the device into the full power-down mode. Drive SHDN
high to exit full power-down mode and return to normal
operating mode. SHDN overrides any software-controlled
power-down mode and every time it is deasserted, it
places the MAX1332/MAX1333 in its normal mode of
operation regardless of its previous state.
Transfer Function
The MAX1332/MAX1333 output is straight binary in
unipolar mode and is two’s complement in bipolar mode.
Figure 9 shows the unipolar transfer function for the
MAX1332/MAX1333. Table 1 shows the unipolar relation-
ship between the differential analog input voltage and
the digital output code. Figure 10 shows the bipolar
transfer function for the MAX1332/MAX1333. Table 2
shows the bipolar relationship between the differential
analog input voltage and the digital output code.
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