LTC2446 LINER [Linear Technology], LTC2446 Datasheet - Page 7

• Manufacturer Part Number: LTC2446
• Description: 24-Bit High Speed 8-Channel ?? ADCs with Selectable Multiple Reference Inputs
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
CONVERTER OPERATION
Converter Operation Cycle
The LTC2446/LTC2447 are multichannel, multireference
high speed, delta-sigma analog-to-digital converters with
an easy to use 3- or 4-wire serial interface (see Figure 1).
Their operation is made up of three states. The converter
operating cycle begins with the conversion, followed by
the low power sleep state and ends with the data output/
input (see Figure 2). The 4-wire interface consists of serial
data input (SDI), serial data output (SDO), serial clock
(SCK) and chip select (CS). The interface, timing, opera-
tion cycle and data out format is compatible with Linear’s
entire family of ∆Σ converters.
Initially, the LTC2446/LTC2447 perform a conversion.
Once the conversion is complete, the device enters the
FU CTIO AL BLOCK DIAGRA
TEST CIRCUITS
U
U
SDO
V
V
V
V
V
V
REF01
REF01
REF67
REF67
REFG
REFG
COM
GND
CH0
CH1
CH7
U
+
–
+
–
+
–
Hi-Z TO V
V
V
1.69k
OL
OH
•
•
•
•
•
•
TO V
TO Hi-Z
U
OH
OH
C
LOAD
W
24467 TA03
REF
REF
IN
IN
+
–
= 20pF
+
–
∆Σ MODULATOR
DIFFERENTIAL
Figure 1. Functional Block Diagram
3RD ORDER
U
W
AUTOCALIBRATION
DECIMATING FIR
AND CONTROL
ADDRESS
Figure 2. LTC2446/LTC2447 State Transition Diagram
OSCILLATOR
INTERFACE
INTERNAL
SERIAL
LTC2446/LTC2447
SDO
REFERENCE SELECT
OSR=256,1X MODE
IN
CHANNEL SELECT
24467 F01
REF
REF
SPEED SELECT
DATA OUTPUT
+
=CH0, IN
POWER UP
Hi-Z TO V
V
V
CONVERT
CS = LOW
+
OH
OL
–
SCK
SLEEP
= V
= V
AND
V
TO Hi-Z
TO V
CC
REFO1
REF01
1.69k
YES
–
C
OL
OL
=CH1
24467 F02
LOAD
+
–
,
V
F
(INT/EXT)
SDI
SCK
SDO
CS
O
CC
24467 TA04
NO
= 20pF
24467fa
7