DS1851
Dual Temperature-Controlled NV
Digital-to-Analog Converters
www.maxim-ic.com
FEATURES
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Two temperature-controlled 8-bit Digital-to-
Analog Converters (DACs)
DAC settings changeable every 4°C
Access to temperature data and device
control through a 2-wire interface
Operates with +3.3V or +5V supplies
Packaging: 8-pin TSSOP
Operating temperature: -40ºC to +95ºC
Programming temperature: 0ºC to +70ºC
PIN ASSIGNMENTS
SDA
SCL
V
rg
GND
1
2
3
4
8
7
6
5
V
CC
V
rc
OutV
OutG
8-Pin TSSOP (173mil)
PIN DESCRIPTIONS
V
CC
GND
SDA
SCL
OutG
V
rg
OutV
V
rc
- +3.3V or +5V Power Supply
Input
- Ground
- 2-Wire Serial Data
Input/Output
- 2-Wire Serial Clock Input
- DAC Output with Respect to
Ground
- Reference Input from Ground
- DAC Output with Respect to
V
CC
- Reference Input from V
CC
ORDERING INFORMATION
DS1851E-010
8-pin 173mil TSSOP
DS1851E-010/T&R 8-pin Tape and Reel
TSSOP
DESCRIPTION
The DS1851 dual temperature-controlled nonvolatile (NV) DACs consists of two DACs, two EEPROM
look-up tables, and a direct-to-digital temperature sensor. Both of the DACs can be programmed with any
temperature coefficient, which means that any system temperature effects can be corrected without any
additional external devices. The DS1851 provides an ideal method for setting and temperature-
compensating bias voltages and currents in control applications using a minimal amount of external
circuitry.
The user-defined settings for both DACs are stored in two EEPROM look-up tables and can be accessed
over the industry-standard 2-wire serial bus, which consists of SDA and SCL pins. These look-up tables
can assign a unique output value to each DAC for every 4°C increment over the -40°C to +95°C range.
The output of the digital temperature sensor is also available as a 12-bit, two’s complement value over the
serial bus.
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010202
DS1851
DS1851 BLOCK DIAGRAM
Figure 1
40x8 bit
40x8 bit
EEPROM
EEPROM
Look-Up Table 1 Look-Up Table 2
(DAC-G)
(DAC-V)
SDA
SCL
V
CC
GND
2-Wire
Interface
Table Select Byte
Configuration Byte
Temperature MSB
Byte
Digital
Temperature
Sensor
Temperature LSB
Byte
Address Pointer
User Memory
DAC-V Setting
DAC-G Setting
User Memory
8-bit DAC-V
8-bit DAC-G
GND
V
rg
OutG
V
CC
V
rc
OutV
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DS1851
PIN DESCRIPTIONS
Name
V
CC
GND
SDA
Pin
8
4
1
Description
Power-Supply Terminal.
The DS1851 will support supply
voltages ranging from 3.0V to 5.5V.
Ground Terminal
2-Wire Serial Data Interface.
The serial data pin is for serial data
transfer to and from the DS1851. The pin is open drain and may be
wire-OR’ed with other open-drain or open-collector interfaces.
2-Wire Serial Clock Input.
The serial clock input is used to clock
data into the DS1851 on rising edges and clock data out on falling edges.
DAC-G Output.
This calculated output is between V
CC
and V
rg
.
DAC-V Output.
This calculated output is between V
CC
and V
rc
.
Reference Input from GND.
This input is used for a reference in DAC-G.
Reference Input from V
CC
.
This input is used for a reference in the
DAC-V.
SCL
OutG
OutV
V
rg
V
rc
2
5
6
3
7
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DS1851
MEMORY ORGANIZATION
60h
Table Select Byte
61h Configuration Byte
62h
63h
64h
65h-6Fh
70h
71h
72h-7Fh
80h
Temperature MSB
Temperature LSB
Address Pointer
User Memory
DAC-V Setting
DAC-G Setting
User Memory
40x8 bit
40x8 bit
EEPROM
EEPROM
Look-Up Table 1 Look-Up Table 2
A7h
(DAC-V)
(DAC-G)
Read-Only
Memory (TBD)
Read-Only
Memory (TBD)
F8h-FFh
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DS1851
MEMORY LOCATIONS
Memory Location
60h
Name of Location
Table Select Byte
Function of Location
Writing to this byte determines which of the two
40x8 EEPROM look-up tables is selected for
reading or writing.
00h (Table 01h selected)
01h (Table 02h selected)
POL TAU TEN AEN
61h
Configuration Byte
POL — Analog Updating
TAU — Temperature/Address Update
TEN — Temperature Update Enable
AEN — Address Update Enable
Default setting is 0Fh, TAU = 1, TEN = 1, and
AEN = 1.
POL = 1 until power is high enough to guarantee
outputs from the analog temperature converter.
Once POL = 0, automated updates will begin.
TAU becomes a 1 after a temperature and
address update has occurred as a result of a
temperature conversion. The user can write this
bit to 0 and check for a transition from 0 to 1 in
order to verify that a conversion has occurred.
If TEN = 0, the temperature conversion feature
is disabled. The user sets the DAC in manual
mode by writing to addresses 70h and
71h to control DAC-V and DAC-G, respectively.
With AEN = 0 the user can operate in a test
mode. Address updates made from the
temperature sensor will cease. The user can load
a memory location into 64h and verify that the
values in locations 70h and 71h are the expected
user-defined values.
This byte contains the MSB of the 12-bit 2’s
complement temperature output from the
temperature sensor.
S
2
6
2
5
2
4
2
3
2
2
2
1
2
0
62h
Temperature MSB
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