DS2422 Maxim, DS2422 Datasheet - Page 7

• Manufacturer Part Number: DS2422
• Description: The DS2422 temperature/data logger combines the core functions of a fully featured data logger in a single chip
• Manufacturer: Maxim

under the control of SCLK. The DS2422 will activate its alarm output if the measured temperature or serial-input
data reaches a user-programmed high or low alarm threshold. This alarm then can be used to shut down the
equipment and enforce a service call. In contrast to microprocessor-based data loggers, the DS2422 does not
require any firmware development. Software for setup and data retrieval through the 1-Wire interface is available
for free download from the iButton website (www.ibutton.com). This software also includes drivers for the serial and
USB port 1-Wire interfaces of a PC, and routines to access the general-purpose memory for storing application or
equipment-specific data files.
Figure 1. Simple Temperature Logger
Figure 2. Temperature and Voltage Logger With Thermocouple
Note: When using a positive/negative thermocouple, an offset voltage can be utilized through the Ref input of the
INA122 amplifier. This voltage shifts the 0V output of the amplifier up the amount equal to the offset voltage
allowing negative voltages to be read in the positive range of the MAX1086. This offset voltage may be obtained
through a simple resistor divider network (not shown).
1-Wire
GND
1-Wire
GND
BR1225R
BR1225R
Lithium
Lithium
1
2
1
2
DS9503
DS9503
IC2
IC4
1
2
1
2
DS9503
DS9503
6
5
IC3
IC5
6
5
6
5
6
5
32768Hz
32768Hz
SPT2AF
SPT2AF
SEIKO
SEIKO
IO
IO
X1
X1
X2
X2
VBAT
V
GND
GND
AGND
AGND
TEST_SPLY
TEST_RX
IO
IO
X1
X1
X2
X2
VBAT
V
GND
GND
AGND
AGND
TEST_SPLY
TEST_RX
BAT
BAT
DS2422
DS2422
IC1
IC1
PUMP_ONZ
PUMP_ONZ
PUMP_ONZ
PUMP_ONZ
OSC_TEST
OSC_TEST
TEST_EXT
CLK_TEST
TEST_EXT
CLK_TEST
TEST_CG
TEST_CG
7 of 49
ALARM
ALARM
CNVST
CNVST
SDATA
SDATA
ALARM
ALARM
CNVST
CNVST
SDATA
SDATA
VPAD
SCLK
SCLK
VPAD
SCLK
SCLK
V
V
PAD
PAD
R1
470
Leave
open
C1
0.1F
1
5
6
8
7
1.5V LED
VDD
REF
CNVST
SCLK
DOUT
Leave
open
D1
MAX1086
IC2
5V
AIN1
AIN2
GND
2
3
4
R2
200k
Thermocouple
Type E, J, K, N
R4
2.2k
R3
2k
7
8
1
6
3
2
5
4
V+
RG
RG
Vo
Vin+
Vin-
Ref
V-
INA122
IC3