LTC2492 Linear Technology, LTC2492 Datasheet - Page 20

• Manufacturer Part Number: LTC2492
• Description: 24-Bit 2-/4-Channel ADC
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
LTC2492
from the output code (DATAOUT
using the following formula:
If a different value of V
is:
If the value of V
measuring the temperature sensor at a known temperature
T
This value of slope can be used to calculate further
temperature readings using:
20
N
T
T
SLOPE = DATAOUT
T
(in °K) and using the following formula:
K
K
K
Figure 4. Internal PTAT Digital Output vs Temperature
= DATAOUT
= DATAOUT
= DATAOUT
140000
120000
100000
80000
60000
40000
20000
0
0
REF
V
V
SLOPE = 314 LSB
CC
REF
24
24
24
is not known, the slope is determined by
= 5V
= 5V
/314 in Kelvin
/SLOPE
• V
100
Table 5. Serial Interface Timing Modes
CONFIGURATION
External SCK, Single Cycle
Conversion
External SCK, 3-Wire I/O
Internal SCK, Single Cycle
Conversion
Internal SCK, 3-Wire I/O,
Continuous Conversion
REF
24
REF
TEMPERATURE (K)
/T
is used, the temperature output
N
/1570 in Kelvin
24
/K
200
24
) for a 5V reference
300
2492 F04
400
SOURCE
External
External
Internal
Internal
SCK
CYCLE CONTROL
CONVERSION
CS and SCK
Continuous
CS↓
SCK
All Kelvin temperature readings can be converted to T
(°C) using the fundamental equation:
SERIAL INTERFACE TIMING MODES
The LTC2492’s 4-wire interface is SPI and MICROWIRE
compatible. This interface offers several fl exible modes
of operation. These include internal/external serial clock,
3- or 4-wire I/O, single cycle or continuous conversion. The
following sections describe each of these timing modes
in detail. In all cases, the converter can use the internal
oscillator (F
to the F
input format, data output format, and performance remain
the same. Refer to Table 5 for a summary.
T
C
= T
DATA OUTPUT
O
CS and SCK
K
CONTROL
pin. For each mode, the operating cycle, data
Internal
– 273
SCK
CS↓
O
–3
–4
–5
–1
–2
Figure 5. Absolute Temperature Error
5
4
3
2
1
0
–55
= LOW) or an external oscillator connected
–30
CONNECTION AND
–5
WAVEFORMS
Figures 9, 10
TEMPERATURE (°C)
Figures 6, 7
Figure 11
Figure 8
20
45
70
95
2492 F05
120
2492fb
C