LTC2245
8
2245fa
SENSE (Pin 30): Reference Programming Pin. Connecting
SENSE to VCM selects the internal reference and a ±0.5V
input range. VDD selects the internal reference and a ±1V
input range. An external reference greater than 0.5V and
less than 1V applied to SENSE selects an input range of
±VSENSE. ±1V is the largest valid input range.
UU
U
PI FU CTIO S
FUNCTIONAL BLOCK DIAGRA
UU
W
SHIFT REGISTER
AND CORRECTION
DIFF
REF
AMP
REF
BUF
2.2
F
1
F1F
0.1
F
INTERNAL CLOCK SIGNALS
REFH
REFL
CLOCK/DUTY
CYCLE
CONTROL
RANGE
SELECT
1.5V
REFERENCE
FIRST PIPELINED
ADC STAGE
FIFTH PIPELINED
ADC STAGE
SIXTH PIPELINED
ADC STAGE
FOURTH PIPELINED
ADC STAGE
SECOND PIPELINED
ADC STAGE
REFH
REFL
CLK
OE
MODE
OGND
OVDD
2245 F01
INPUT
S/H
SENSE
VCM
AIN
–
AIN
+
2.2
F
THIRD PIPELINED
ADC STAGE
OUTPUT
DRIVERS
CONTROL
LOGIC
SHDN
OF
D13
D0
Figure 1. Functional Block Diagram
VCM (Pin 31): 1.5V Output and Input Common Mode Bias.
Bypass to ground with 2.2
F ceramic chip capacitor.
GND (Exposed Pad) (Pin 33): ADC Power Ground. The
exposed pad on the bottom of the package needs to be
soldered to ground.