LTC2424 Linear Technology, LTC2424 Datasheet - Page 27

• Manufacturer Part Number: LTC2424
• Description: 4-/8-Channel 20-Bit uPower No Latency ADCs
• Manufacturer: Linear Technology

APPLICATIONS
PACKAGE DESCRIPTIO
These infrared thermocouples are self-contained: 1) they
do not require external cold junction compensation; 2)
they cannot use conventional open thermocouple detec-
tion schemes; and 3) their output impedances are high,
approximately 3k . Alternatively, conventional thermo-
couples can be connected directly to the LTC2428 (not
shown) and cold junction compensation can be provided
by an external temperature sensor connected to a different
channel (see the thermistor circuit on CH5) or by using the
LT1025, a monolithic cold-junction compensator IC.
The components connected to CH7 are used to sense
daylight or photodiode current with a resolution of 300pA.
In the figure, the photodiode is biased in photoconduc-
tive mode; however, the LTC2428 can accommodate
either photovoltaic or photoconductive configurations.
(0.005 – 0.009)
**
*
0.13 – 0.22
NOTE: DIMENSIONS ARE IN MILLIMETERS
DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.152mm (0.006") PER SIDE
DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.254mm (0.010") PER SIDE
U
(0.205 – 0.212)
INFORMATION
5.20 – 5.38**
U
(0.022 – 0.037)
0.55 – 0.95
W
U
Dimensions in millimeters (inches) unless otherwise noted.
28-Lead Plastic SSOP (0.209)
0 – 8
U
(LTC DWG # 05-08-1640)
G Package
(0.0256)
0.65
BSC
The photodiode chosen (Hammatsu S1336-5BK) pro-
duces an output of 500mA per watt of optical illumination.
The output of the photodiode is dependent on two factors:
active detector area (2.4mm • 2.4mm) and illumination
intensity. With the 5k resistor, optical intensities up to
368W/m
1000W/m
resolution of 1nA, the optical dynamic range covers 5
orders of magnitude.
The application circuits shown connected to the LTC2428
demonstrate the mix-and-match capabilities of this multi-
plexed-input, high resolution
signals and high level signals can be accommodated with
a minimum of additional circuitry.
28
1 2 3 4 5 6 7 8 9 10 11 12
(0.010 – 0.015)
27
0.25 – 0.38
26
25
2
2
24
at 960nM (direct sunlight is approximately
) can be measured by the LTC2428. With a
(0.397 – 0.407)
10.07 – 10.33*
23
22 21 20 19 18 17 16 15
LTC2424/LTC2428
13
(0.002 – 0.008)
14
0.05 – 0.21
(0.068 – 0.078)
1.73 – 1.99
ADC. Very low level
(0.301 – 0.311)
G28 SSOP 1098
7.65 – 7.90
27