LTC2442IG Linear Technology, LTC2442IG Datasheet - Page 9

• Manufacturer Part Number: LTC2442IG
• Description: IC,A/D CONVERTER,SINGLE,24-BIT,CMOS,SSOP,36PIN
• Manufacturer: Linear Technology

FU CTIO AL BLOCK DIAGRA
TEST CIRCUITS
APPLICATIO S I FOR ATIO
CONVERTER OPERATION
Converter Operation Cycle
The LTC2442 is a multi-channel, high speed, ΔΣ analog-
to-digital converter with an easy to use 3- or 4-wire serial
interface (see Figure 1). Its operation is made up of three
states. The converter operating cycle begins with the con-
version, followed by the 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,
operation cycle and data out format is compatible with
Linear’s entire family of ΔΣ converters.
Initially, the LTC2442 performs a conversion. Once the
conversion is complete, the device enters the sleep state.
The part remains in the sleep state as long as CS is HIGH.
The conversion result is held indefi nitely in a static shift
register while the converter is in the sleep state.
U
COM
GND
CH0
CH1
CH2
CH3
V
U
CC
SDO
U
MUX
Hi-Z TO V
V
V
1.69k
OL
OH
MUXOUTB
MUXOUTA +INA –INA
TO V
U
TO Hi-Z
OH
OH
+INB
C
LOAD
W
–INB
2442 TA03
= 20pF
–
+
+
–
V
+
AMPB
AMPA
V
Figure 1. Functional Block Diagram
–
OUTB
OUTA
U
W
ADCINB
ADCINA
IN
IN
REF
+
–
∆Σ MODULATOR
+
DIFFERENTIAL
3RD ORDER
REF
–
Figure 2. LTC2442 State Transition Diagram
AUTOCALIBRATION
DECIMATING FIR
AND CONTROL
ADDRESS
SDO
Hi-Z TO V
V
V
OH
OL
V
TO Hi-Z
TO V
OSR=256,1X MODE
IN
CHANNEL SELECT
CC
SPEED SELECT
DATA OUTPUT
+
OSCILLATOR
INTERFACE
1.69k
=CH0, IN
INTERNAL
POWER UP
C
OL
CONVERT
CS = LOW
OL
SERIAL
SCK
LOAD
SLEEP
AND
2442 F01
2442 TA04
= 20pF
–
=CH1
2442 F02
F
BUSY
SDI
SCK
SDO
CS
EXT
LTC2442
O
9
2442f