Datasheet

32
LTC2421/LTC2422
24212f
LT/TP 0202 2K • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2002
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LT1019 Precision Bandgap Reference, 2.5V, 5V 3ppm/°C Drift, 0.05% Max
LTC1050 Precision Chopper Stabilized Op Amp No External Components 5µV Offset, 1.6µV
P-P
Noise
LT1236A-5 Precision Bandgap Reference, 5V 0.05% Max, 5ppm/°C Drift
LTC1391 8-Channel Multiplexer Low R
ON
: 45Ω, Low Charge Injection Serial Interface
LT1461-2.5 Precision Micropower Voltage Reference 50µA Supply Current, 3ppm/°C Drift
LTC1535 Isolated RS485 Transceiver 2500V
RMS
Isolation
LTC2400 24-Bit, No Latency ∆Σ ADC in SO-8 4ppm INL, 10ppm Total Unadjusted Error, 200µA
LTC2401/LTC2402 1-/2-Channel, 24-Bit, No Latency ∆Σ ADC in MSOP 0.6ppm Noise, 4ppm INL, Pin Compatible with the LTC2421/LTC2422
LTC2404/LTC2408 4-/8-Channel, 24-Bit, No Latency ∆Σ ADC 4ppm INL, 10ppm Total Unadjusted Error, 200µA
LTC2413 24-Bit, No Latency ∆Σ ADC Simultaneous 50Hz and 60Hz Rejection, 0.16ppm Noise
LTC2415 24-Bit, Fully Differential, No Latency ∆Σ ADC 15Hz Output Rate at 60Hz Rejection, Pin Conpatible with the LTC2410
LTC2420 20-Bit, No Latency ∆Σ ADC in SO-8 1.2ppm Noise, 8ppm INL, Pin Compatible with LTC2400
LTC2424/LTC2428 4-/8-Channel, 20-Bit, No Latency ∆Σ ADC 1.2ppm Noise, 8ppm INL, Pin Compatible with LTC2404/LTC2408
LTC2430 20-Bit, Fully Differential, No Latency ∆Σ ADC in SSOP-16 0.16ppm Noise, 2ppm INL, 10ppm Total Unadjusted Error, 200µA
LTC2431 24-Bit, Fully Differential, No Latency ∆Σ ADC in MS10 0.29ppm Noise, 4ppm INL, 10ppm Total Unadjusted Error, 200µA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone]
●
FAX: [phone]
●
www.linear.com
TYPICAL APPLICATIO
U
Figure 37 shows the block diagram of a demo circuit
(contact LTC for a demonstration) of a multichannel
isolated temperature measurement system. This circuit
decodes an address to select which LTC2422 receives a
24-bit burst of SCK signal. All devices independently
convert either the thermal couple output or the thermistor
cold junction output. After each conversion, the devices
enter their sleep state and wait for the SCK signal before
clocking out data and beginning the next conversion.
V
CC
FS
SET
CH1
SDO
SCK
CH0
ZS
SET
LTC2422
A
Y
D1
RE
R0
LTC1535
V
CC
FS
SET
CH1
SDO
SCK
CH0
2500V
ZS
SET
LTC2422
A
Y
D1
RE
R0
LTC1535
V
CC
FS
SET
CH1
SDO
SCK
24212 F37
CH0
ZS
SET
LTC2422
A
Y
D1
HC138
HC595
ADDRESS
LATCH
RE
R0
LTC1535
SEE FIGURE 34 FOR
THE COMPLETE CIRCUIT
HC138SCK
SD0
D
IN
(ADDRESS
OR COUNTER)
+
–
Figure 37. Mulitchannel Isolated Temperature Measurement System