Datasheet

LTC1857/LTC1858/LTC1859
8
185789fa
FUNCTIONAL BLOCK DIAGRAM
PIN FUNCTIONS
DGND (Pin 24): Digital Ground.
SDI (Pin 25): Serial Data Input.
SCK (Pin 26): Serial Data Clock.
RD (Pin 27): Read Input. This active low signal enables
the digital output pin SDO.
CONVST (Pin 28): Conversion Start. This active high signal
starts a conversion on its rising edge.
TEST CIRCUITS
2.5V
REFERENCE
INTERNAL
CLOCK
1.6384X
4.096V
8k
AGND1
CONTROL
LOGIC
SERIAL I/O
INPUT MUX
AND
RANGE
SELECT
AGND3
AGND2REFCOMPV
REF
ADC
–
MUXOUT
+
MUXOUT
–
ADC
+
DGND
AV
DD
DV
DD
MUX ADDRESS AND RANGE
DATA OUT
CONVST
SDI
BUSY
SCK
RD
OV
DD
SDO
1859 BD
12-/14-/16-BIT
SAMPLING ADC
+
–
COM
CH7
CH1
•
•
•
CH0
1k
(A) Hi-Z TO V
OH
AND V
OL
TO V
OH
25pF
1k
5V
DNDN
(B) Hi-Z TO V
OL
AND V
OH
TO V
OL
25pF
1859 TC01
1k
(A) V
OH
TO Hi-Z
25pF
1k
5V
DNDN
(B) V
OL
TO Hi-Z
25pF
1859 TC02
Load Circuits for Access Timing
Load Circuits for Output Float Delay