Linear Technology DC845A - LTC2448UHF | 24-Bit High Speed 8-/16-Channel Delta Sigma ADC (req DC590) DC845A DC845A Scheda Tecnica
Codici prodotto
DC845A
LTC2444/LTC2445/
LTC2448/LTC2449
1
2444589fb
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
■
High Speed Multiplexing
■
Weight Scales
■
Auto Ranging 6-Digit DVMs
■
Direct Temperature Measurement
■
High Speed Data Acquisition
■
Up to 8 Differential or 16 Single-Ended Input
Channels
Channels
■
Up to 8kHz Output Rate
■
Up to 4kHz Multiplexing Rate
■
Selectable Speed/Resolution
■
2
µV
RMS
Noise at 1.76kHz Output Rate
■
200nV
RMS
Noise at 13.8Hz Output Rate with
Simultaneous 50/60Hz Rejection
■
Guaranteed Modulator Stability and Lock-Up
Immunity for any Input and Reference Conditions
Immunity for any Input and Reference Conditions
■
0.0005% INL, No Missing Codes
■
Autosleep Enables 20
µA Operation at 6.9Hz
■
< 5
µV Offset (4.5V < V
CC
< 5.5V, – 40
°C to 85°C)
■
Differential Input and Differential Reference with
GND to V
GND to V
CC
Common Mode Range
■
No Latency Mode, Each Conversion is Accurate Even
After a New Channel is Selected
After a New Channel is Selected
■
Internal Oscillator—No External Components
■
LTC2445/LTC2449 Include MUXOUT/ADCIN for
External Buffering or Gain
External Buffering or Gain
■
Tiny QFN 5mm x 7mm Package
24-Bit High Speed
8-/16-Channel
∆Σ ADCs with
Selectable Speed/Resolution
The LTC
®
2444/LTC2445/LTC2448/LTC2449 are 8-/16-
channel (4-/8-differential) high speed 24-bit No Latency
∆Σ
TM
ADCs. They use a proprietary delta-sigma architec-
ture enabling variable speed/resolution. Through a simple
4-wire serial interface, ten speed/resolution combinations
6.9Hz/280nV
4-wire serial interface, ten speed/resolution combinations
6.9Hz/280nV
RMS
to 3.5kHz/25
µV
RMS
(4kHz with external
oscillator) can be selected with no latency between con-
version results or shift in DC accuracy (offset, full-scale,
linearity, drift). Additionally, a 2X speed mode can be
selected enabling output rates up to 7kHz (8kHz if an
external oscillator is used) with one cycle latency.
version results or shift in DC accuracy (offset, full-scale,
linearity, drift). Additionally, a 2X speed mode can be
selected enabling output rates up to 7kHz (8kHz if an
external oscillator is used) with one cycle latency.
Any combination of single-ended or differential inputs can
be selected with a common mode input range from ground
to V
be selected with a common mode input range from ground
to V
CC
, independent of V
REF
. While operating in the 1X
speed mode the first conversion following a new speed,
resolution, or channel selection is valid. Since there is no
settling time between conversions, all 8 differential chan-
nels can be scanned at a rate of 500Hz. At the conclusion
of each conversion, the converter is internally reset elimi-
nating any memory effects between successive conver-
sions and assuring stability of the high order delta-sigma
modulator.
resolution, or channel selection is valid. Since there is no
settling time between conversions, all 8 differential chan-
nels can be scanned at a rate of 500Hz. At the conclusion
of each conversion, the converter is internally reset elimi-
nating any memory effects between successive conver-
sions and assuring stability of the high order delta-sigma
modulator.
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTC2444/LTC2448
Speed vs RMS Noise
Simple 24-Bit Variable Speed Data Acquisition System
SDI
SCK
SDO
CS
F
O
REF
+
V
CC
4.5V TO 5.5V
1
µF
COM
REF
–
GND
THERMOCOUPLE
VARIABLE SPEED/
RESOLUTION
DIFFERENTIAL
24-BIT
∆Σ ADC
16-CHANNEL
MUX
+
–
2444 TA01
4-WIRE
SPI INTERFACE
SPI INTERFACE
LTC2448
= EXTERNAL OSCILLATOR
= INTERNAL OSCILLATOR
(SIMULTANEOUS 50Hz/60Hz
REJECTION AT 6.9Hz OUTPUT RATE)
= INTERNAL OSCILLATOR
(SIMULTANEOUS 50Hz/60Hz
REJECTION AT 6.9Hz OUTPUT RATE)
CH0
CH1
CH1
•
•
•
•
•
•
CH7
CH8
CH8
CH15
CONVERSION RATE (Hz)
1
0.1
RMS NOISE (
µ
V)
1
10
100
10
100
2440 TA02
1000
10000
2.8
µV AT 880Hz
280nV AT 6.9Hz
(50/60Hz REJECTION)
V
CC
= 5V
V
REF
= 5V
V
IN
+
= V
IN
–
= 0V
2X SPEED MODE
NO LATENCY MODE
NO LATENCY MODE
No Latency
∆Σ is a trademark of Linear Technology Corporation.