MAX1402_07 Datasheet, PDF (37/38 Pages) Maxim Integrated Products – +5V, 18-Bit, Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC

+5V, 18-Bit, Low-Power, Multichannel,
Oversampling (Sigma-Delta) ADC
R_REF
RTD
+5V
OUT2
REFIN+
REFIN-
OUT1
V+
V_DD
200µA
MAX1402
MODULATOR
200µA
AIN1
AIN2
AGND
PGA
A = 1 TO 128
DGND
ISO
+5V
+V_DD
V_{CC 6N136}
2k
DIN
MOSI
470Ω
V_CC
6N136
2k
MAX1402
SCLK
470Ω
SCK
V_CC
2k
MISO
6N136
470Ω
Figure 20. 4-Wire RTD Application
board is dedicated to ground planes while signals are
placed on the solder side.
Good decoupling is important when using high-resolu-
tion ADCs. Decouple all analog supplies with 10µF tan-
talum capacitors in parallel with 0.1µF HF ceramic
capacitors to AGND. Place these components as close
to the device as possible to achieve the best decou-
pling.
See the MAX1402 evaluation kit manual for the recom-
mended layout. The evaluation board package includes
a fully assembled and tested evaluation board.
Optical Isolation
For applications that require an optically isolated
interface, refer to Figure 21. With 6N136-type optocou-
plers, maximum clock speed is 4MHz. Maximum clock
speed is limited by the degree of mismatch between
the individual optocouplers. Faster optocouplers allow
faster signaling at a higher cost.
DOUT
V_CC
2k
470Ω INT
INT
6N136
Figure 21. Optically Isolated Interface
Chip Information
TRANSISTOR COUNT: 34,648
SUBSTRATE CONNECTED TO AGND
Revision History
Pages changed at Rev2: 1, 37, 38
______________________________________________________________________________________ 37