
DS2450
1–Wire
TM
 Quad A/D Converter
DS2450
PRELIMINARY
091598 1/23
FEATURES
 Four high–impedance inputs to measure analog volt-
ages over the 1–Wire bus
 User programmable input range (2.56V, 5.12V), reso-
lution (1 to 16 bits) and alarm thresholds
 5V, single supply operation
 Very low power: 2.5mW active, 25 
μ
W idle
 Built–in multidrop controller allows multiple DS2450’s
to be identified and operated on a common 1–Wire
bus
 Responds to Conditional Search if the analog voltage
crosses the alarm thresholds
 Channels not used as analog input can serve as open
drain digital outputs for closed–loop control
 Directly connects to a single port pin of a microproces-
sor and communicates at up to 16.3k bits per second
 Overdrive mode boosts communication speed to
142k bits per second
 On–chip 16–bit CRC–generator for safeguarding
data transfers
 Unique, factory–lasered and tested 64–bit registra-
tion number (8–bit family code + 48–bit serial number
+ 8–bit CRC tester) assures absolute traceability
because no two parts are alike
 8–bit family code specifies device communication
requirements to bus master
 Operating temperature range from –40
°
C to +85
°
C
 Compact, low cost 8–pin SOIC surface mount pack-
age
DESCRIPTION
The DS2450 1–Wire Quad A/D Converter is based on a
successive–approximation analog to digital converter
with a four to one analog multiplexer. Each input chan-
nel has its own register set to store the input voltage
range, resolution, and alarm threshold values as well as
flags to enable participation of the device in the condi-
tional search if the input voltage leaves the specified
range. Two alarm flags for each channel indicate if the
voltage measured was too high or too low without
requiring the bus master to do the comparison. Each
A/D conversion is initiated by the bus master. A channel
not used as analog input can serve as a digital open–
drain output. After disabling the input the bus master
PIN ASSIGNMENT
8
7
6
5
1
2
3
4
VCC
NC
DATA
GND
AIN–D
AIN–C
AIN–B
AIN–A
8–PIN SOIC (208 MIL)
PIN DESCRIPTION
V
CC
NC
DATA
GND
AIN–A
AIN–B
AIN–C
AIN–D
4.5 to 5.5 Volts
NOT CONNECTED
1–Wire Bus
Ground
Analog Input A
Analog Input B
Analog Input C
Analog Input D
ORDERING INFORMATION
DS2450S
8–pin SOIC
can directly switch on or off the open–drain transistor at
the selected channel. All device settings are stored in
SRAM and kept non–volatile while the device gets
power either through the 1–Wire bus or through its V
CC
pin. After powering up a power–on reset flag signals the
bus master the need to restore the device settings
before the regular operation can resume. All device reg-
isters and conversion read–out registers are organized
as three 8–byte memory pages similar to the Status
Memory of a DS2505/6 device. An on–chip CRC16 gen-
erator protects the communication against transmission
errors when reading through the end of a memory page
as well as when writing individual bytes.