MAX1179 Datasheet, PDF (9/15 Pages) Maxim Integrated Products – 16-Bit, 135ksps, Single-Supply ADCs with Bipolar Analog Input Range

16-Bit, 135ksps, Single-Supply ADCs with
Bipolar Analog Input Range
MAX1187
R2
AIN
161Ω
R3
3.4kΩ
TRACK
S1
C_HOLD
30pF
HOLD _TRACK
T/H OUT
HOLD
S2
MAX1179/MAX1189
R2
AIN
161Ω
REF
3.4kΩ
TRACK
S1
C_HOLD
30pF
R3
S3
POWER-
DOWN
HOLD _TRACK
T/H OUT
HOLD
S2
Figure 4. Equivalent Input Circuit
S1, S2 = T/H SWITCH
S3 = POWER-DOWN
(MAX1179/MAX1189
ONLY)
R2 = 7.85kΩ (MAX1189)
OR 3.92kΩ (MAX1179/MAX1187)
R3 = 5.45kΩ (MAX1189)
OR 17.79kΩ (MAX1179/MAX1187)
ACQUISITION
CONVERSION
DATA
OUT
CS
R/C
EOC
REF AND
BUFFER
POWER
Figure 5. Selecting Standby Mode
completing a conversion. The reference and reference
buffer require a minimum of 12ms (C_REFADJ = 0.1µF,
C_REF = 10µF) to power up and settle from shutdown.
The state of R/C during the second falling edge of CS
selects which power-down mode the MAX1179/
MAX1187/MAX1189 enters upon conversion comple-
tion. Holding R/C low causes the MAX1179/MAX1187/
MAX1189 to enter standby mode. The reference and
buffer are left on after the conversion completes. R/C
high causes the MAX1179/MAX1187/MAX1189 to enter
shutdown mode and power down the reference and
buffer after conversion (see Figures 5 and 6). Set the
voltage at REF high during the second falling edge of
CS to realize the lowest current operation.
Standby Mode
While in standby mode, the supply current is less than
3.7mA (typ). The next falling edge of CS with R/C low
causes the MAX1179/MAX1187/MAX1189 to exit stand-
by mode and begin acquisition. The reference and ref-
erence buffer remain active to allow quick turn-on time.
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