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PDF DS1841 Data sheet ( Hoja de datos )
| Número de pieza | DS1841 | |
| Descripción | Temperature-Controlled | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Rev 0; 11/07
www.DataSheet4U.com
Temperature-Controlled, NV, I2C,
Logarithmic Resistor
General Description
The DS1841 is a 7-bit, logarithmic, nonvolatile (NV) digi-
tal resistor that features an on-chip temperature sensor
and associated analog-to-digital converter (ADC). The
integrated temperature sensor indexes a 72-byte NV
lookup table (LUT) encompassing a temperature range
from -40°C to +100°C. The LUT output can drive the
resistor directly or be added to an NV initial-value regis-
ter (IVR) to drive the resistor. This flexible LUT-based
architecture allows the DS1841 to provide a tempera-
ture-compensated resistor output with arbitrary slope.
Programming is accomplished by an I2C-compatible
interface, which can operate at speeds of up to 400kHz.
Applications
Optical Transceivers
Linear and Nonlinear Compensation
Instrumentation and Industrial Controls
Mechanical Potentiometer Replacement
Registers and Modes are capitalized for clarity.
Features
♦ 22kΩ to 3.7kΩ Adjustable Logarithmic Resistor
with a 3.6kΩ Fixed Resistor
♦ 128 Wiper Tap Points
♦ On-Chip Temperature Sensor and ADC
♦ 72-Byte Lookup Table (LUT)
♦ I2C-Compatible Serial Interface
♦ Address Pins Allow Up to Four DS1841s to Share
the Same I2C Bus
♦ Digital Supply of 2.7V to 5.5V
♦ -40°C to +100°C Operating Range
♦ 3mm x 3mm, 10-Pin TDFN Package
Ordering Information
PART
TEMP RANGE
DS1841T+
-40°C to +100°C
DS1841T+T&R
-40°C to +100°C
+Denotes a lead-free package.
T&R = Tape and reel.
PIN-PACKAGE
10 TDFN
10 TDFN
Typical Operating Circuit
3.3V
4.7kΩ 4.7kΩ
SDA
SCL
VCC
GND
DS1841 RH
RW
A1
A0 RGND
VAPD
VOUT
0.1μF DC-DC
CONVERTER
FB
100pF
APD BIAS CONTROL APPLICATION
Pin Configuration
TOP VIEW
SCL N.C. RH RW RGND
10 9 8 7 6
DS1841
*EP
1234
SDA GND VCC A1
5
A0
TDFN
3.0mm × 3.0mm × 0.8mm
*EXPOSED PAD
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1 page  
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Temperature-Controlled, NV, I2C,
Logarithmic Resistor
(VCC = +2.7V to +5.5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
250
200
LUT MODE AND LUT ADDER MODE
UPDATE MODE BIT = 1
150
UPDATE MODE BIT = 0
100
50
0
2.5
SDA = SCL = VCCCC
RGRHN,DR, HR,HR, WRWARAEREFLFOLAOTAITNIGNG
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
5.5
WIPER RESISTANCE (RW)
vs. SETTING
25
SDA = SCL = VCC = 5V
20
15
10
5
0
0 25 50 75 100 125
SETTING (DEC)
SUPPLY CURRENT
vs. TEMPERATURE
250
200
LUT MODE AND LUT ADDER MODE
UPDATE MODE BIT = 1
150
UPDATE MODE BIT = 0
100
50
0
-40
SDSAD=AS=CSLC=LV=CVCC=C5V
RGRHN,DR, HR,HR, WRWARAEREFLFOLAOTAITNIGNG
-20 0 20 40 60 80
TEMPERATURE (°C)
100
WIPER CURRENT
vs. WIPER SETTING
1.6
RGND = 0V
RW OPEN
FORCE 1.25V ON RH AND
1.2 MEASURE CURRENT
0.8
SUPPLY CURRENT
vs. SCL FREQUENCY
250
200 LUT MODE AND LUT ADDER MODE
UPDATE MODE BIT = 1
150
UPDATE MODE BIT = 0
100
50
0
0
SSDDAA==SVCCLC==V5CVC
RGRHN,DR, HR,HR, WRWARAEREFLFOLAOTAITNIGNG
100 200 300
SCL FREQUENCY (kHz)
RW TO RGND RESISTANCE
vs. SUPPLY VOLTAGE
40
POR OCCURS
30
IVR IS LOADED
400
20
0.4
0
0
VCCCC = 5V
SDA AND SCL REFERENCED TO 5V
25 50 75 100
WIPE SETTING (DEC)
125
10
CONVERSIONS COMPLETE
LUT VALUE LOADED TO WR
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________ 5
5 Page 
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Temperature-Controlled, NV, I2C,
Logarithmic Resistor
Register 03h: Control Register 1 (CR1)
FACTORY DEFAULT
MEMORY TYPE
00h
Shadowed NV
03h Reserved
Bit 7
Reserved
Reserved
Reserved
Reserved
Reserved
Adder Mode Update Mode
Bit 0
Bits 7 to 2
Bit 1
Bit 0
Reserved.
Adder Mode This bit is valid only if the Update Mode bit = 1.
0 = (Default) The LUTVAL or IVR value is directly loaded to WR though the mux.
1 = The LUTVAL is summed with the IVR value and is directly loaded to WR though the mux.
Update Mode
0 = (Default) CR0 is enabled. During power-up the IVR value is loaded into the WR to set the wiper
position. Updates to Temperature Result (0Ch) and Supply Voltage Result (0Eh) are halted.
1 = The WR is controlled directly by I2C communication though registers 08h or 09h, or the WR is
controlled by the temperature-compensation/LUT circuitry. If temperature compensation is enabled, one
of the 72 temperature slots is selected (by the LUTAR) and this slot value is copied into the LUTVAL,
which in turn sets the WR. Updates to Temperature Result (0Ch) and Supply Voltage Result (0Eh) are
enabled.
Control Register 1 controls how the wiper position is determined. The SEE bit controls whether the values of this register
are stored in EEPROM or in Shadowed SRAM. On power-up, the EEPROM value is recalled to this register, regardless of
the state of SEE.
While the registers other than 00h through 0Ah can be read, they are not updated by the ADC as the ADC is disabled
with the Update Mode bit = 0.
Register 08h: LUT Address Register (LUTAR)
FACTORY DEFAULT
POR DEFAULT
MEMORY TYPE
00h
00h until tFRAME
Volatile
08h
Bit 7
LUTAR
Bit 0
The LUTAR register serves as the index pointer to choose the corresponding temperature slot in the LUT based on the
internal temperature sensor result. The LUTAR can be directly read by acessing address 08h; however, to write an new
value to LUTAR (to control WR manually), the LUTAR Mode bit must be set to a 1.
Register 09h: LUT Value Register (WR*)
FACTORY DEFAULT
MEMORY TYPE
00h
Volatile
09h WR*
Bit 7
Bit 0
WR serves as an intermediate location, which is populated automatically with the results of the temperature-indexed
lookup. The WR can be directly read by acessing address 09h; however to write an new value to WR (to control it
manually), the wiper access control bit must be set to a 1. WR is an unsigned 7-bit value.
*WR is updated every tFRAME if Update Mode bit = 1. If Update Mode bit = 0, WR holds the value stored in register 00h.
______________________________________________________________________________________ 11
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| PDF Descargar | [ Datasheet DS1841.PDF ] | |
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