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Triple NV Low Step Size Variable
Resistor Plus Memory
General Description
The DS3906 is intended for low resistance, small step-
size applications. It contains three nonvolatile (NV), low-
temperature coefficient, variable digital resistors that
are capable of ohm and subohm increments when
used in parallel with a fixed external resistor. All three of
the DS3906’s resistors have 64 positions (plus a high-Z
state) with a pseudo-log response cleverly chosen to
have a linear equivalent resistance when paired with an
external resistor (see graphs below). The DS3906 also
contains 16 bytes of user EEPROM that, in addition to
the resistors, are controlled through an I
2
C-compatible
serial interface. Three address pins allow up to eight
DS3906s to be placed on the same I
2
C bus.
The DS3906 can also be factory cutomized to provide a
variety of transfer functions depending on user
requirements. Contact mixedsignal.apps@dalsemi.com
for additional information.
Features
♦
Three Programmable Resistors for Low Step-Size
Applications (Ohm and Subohm)
♦
Resistor Settings are NV
♦
16-Byte NV User Memory (EEPROM)
♦
I
2
C-Compatible Serial Interface
♦
Up to 8 Devices Can be Multidropped on the
Same I
2
C Bus
♦
Low Power Consumption
♦
Wide Operating Voltage (2.7V to 5.5V)
♦
Operating Temperature Range: -40°C to +85°C
DS3906
Ordering Information
PART
DS3906U
DS3906U+
DS3906U+T&R
DS3906U/T&R
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µSOP
10 µSOP
10 µSOP
10 µSOP
Applications
Low Ohm, Fine Resolution Driver Control for LED
Display Panels
Low Ohm, Fine Resolution Instrumentation Control
+Denotes
lead-free package.
T&R denotes tape-and-reel package.
Pin Configuration
TOP VEIW
A1 1
SDA 2
10 A2
9
A0
H0
H1
H2
Typical Operating Circuit appears at end of data sheet.
SCL 3
V
CC
GND
4
5
DS3906
8
7
6
μSOP
Resistor Plots
RESISTOR 0 AND 1 RESISTANCE vs. POSITION
(WITH AND WITHOUT EXTERNAL RESISTOR)
200
180
R
EFFECTIVE
= R
0, 1
|| R
EXT
(Ω)
160
140
120
100
80
60
40
20
0
0
16
32
20
R
0, 1
WITHOUT R
EXT
48
64
0
R2
R
EXT2
50
0
0
16
32
48
64
RESISTOR POSITION (dec)
R
0, 1
|| (R
EXT
= 50Ω)
100
500
R
0, 1
|| (R
EXT
= 105Ω)
R
0, 1
|| (R
EXT
= 150Ω)
R
0, 1
WITHOUT R
EXT
(Ω)
2000
1500
3000
2500
R
EFFECTIVE
= R
2
|| R
EXT
(Ω)
R0
R
EXT0
RESISTOR 2 RESISTANCE vs. POSITION
(WITH AND WITHOUT EXTERNAL RESISTOR)
350
R
2
|| (R
EXT
= 400Ω)
300
250
200
1000
150
100
R
2
WITHOUT R
EXT
600
400
R
2
|| (R
EXT
= 250Ω)
800
R
2
|| (R
EXT
= 310Ω)
1400
1200
R
2
WITHOUT R
EXT
(Ω)
1600
DS3906
R1
R
EXT1
RESISTOR POSITION (dec)
______________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Triple NV Low Step Size Variable
Resistor Plus Memory
DS3906
ABSOLUTE MAXIMUM RATINGS
Voltage on V
CC
, SDA, SCL, and H0-H2 Pins
Relative to Ground.............................................-0.5V to +6.0V
Voltage on A0, A1, and A2
Relative to Ground .....-0.5V to V
CC
+ 0.5V, not to exceed +6.0V
Resistor Current ....................................................................5mA
Operating Temperature Range ...........................-40°C to +85°C
EEPROM Programming Temperature Range .........0°C to +70°C
Storage Temperature Range ............................-55°C to +125°C
Soldering Temperature...................See J-STD-020 Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
(T
A
= -40°C to +85°C)
PARAMETER
Supply Voltage
Input Logic 1
Input Logic 0
Resistor Inputs
Resistor Current
SYMBOL
V
CC
V
IH
V
IL
H0, H1, H2 V
CC
= 2.7V to 5.5V
I
R
(Note 1)
CONDITIONS
MIN
+2.7
0.7 x
V
CC
-0.3
-0.3
TYP
MAX
+5.5
V
CC
+
0.3
0.3 x
V
CC
+5.5
5
UNITS
V
V
V
V
mA
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +2.7V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
Standby Current (Note 2)
Input Leakage for All Pins
Low-Level Output Voltage (SDA)
I/O Capacitance
SYMBOL
I
STBY
I
L
V
OL SDA
C
I/O
3V
5V
(Note 3)
3mA sink current
6mA sink current
-1.0
0
0
CONDITIONS
MIN
TYP
130
160
250
+1.0
0.4
0.6
10
MAX
UNITS
µA
µA
V
pF
ANALOG RESISTOR CHARACTERISTICS
(V
CC
= +2.7V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
Resistor Tolerance
INL
DNL
Temperature Coefficient
Resistor High-Z
Resistors
R
HIGH-Z
Guaranteed monotonic by design
SYMBOL
(Note 4)
(Note 4)
At position 3Fh (Note 8)
5.5
CONDITIONS
From nominal values in Table 3
MIN
-20
-2
-0.5
60
TYP
MAX
+20
+2
+0.5
UNITS
%
LSB
LSB
ppm/°C
MΩ
2
_____________________________________________________________________
Triple NV Low Step Size Variable
Resistor Plus Memory
AC ELECTRICAL CHARACTERISTICS (See Figure 2)
(V
CC
= +2.7V to 5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Timing referenced to V
IL(MAX)
and V
IH(MIN)
.)
PARAMETER
SCL Clock Frequency
Bus Free Time Between Stop and
Start Conditions
Hold Time (Repeated) Start
Condition
Low Period of SCL
High Period of SCL
Data Hold Time
Data Set-up Time
Start Set-up time
SDA and SCL Rise Time
SDA and SCL Fall Time
Stop Set-up Time
SDA and SCL Capacitive
Loading
EEPROM Write Time
SYMBOL
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
HD:DAT
t
SU:DAT
t
SU:STA
t
R
t
F
t
SU:STO
C
B
t
WR
(Note 6)
(Note 7)
(Note 6)
(Note 6)
(Note 5)
CONDITIONS
MIN
0
1.3
0.6
1.3
0.6
0
100
0.6
20 +
0.1C
B
20 +
0.1C
B
0.6
400
20
300
300
0.9
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
µs
ns
µs
ns
ns
µs
pF
ms
DS3906
NONVOLATILE MEMORY CHARACTERISTICS
(V
CC
= +2.7V to 5.5V)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
EEPROM Writes
0°C to +70°C. The room temperature
specification is at least 4x better than
specification over 0°C to +70°C.
50,000
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
All voltages referenced to ground.
I
STBY
is specified with SDA = SCL = V
CC
, resistor pins floating, and inputs tied to V
CC
or GND.
The DS3906 will not obstruct the SDA and SCL lines if V
CC
is switched off as long as the voltages applied to these input do
not violate their minimum and maximum input voltage levels.
Tested with external resistor of 87Ω for R
0
and R
1
and 258Ω for R
2
at 25°C.
Timing shown is for fast mode (400kHz) operation. This device is also backward compatible with I
2
C standard mode timing.
C
B
total
capacitance of one bus line in picofarads.
The EEPROM write time begins after a stop condition occurs.
Guaranteed by design.
_____________________________________________________________________
3
Triple NV Low Step Size Variable
Resistor Plus Memory
DS3906
Typical Operating Characteristics
(V
CC
= +5.0V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
DS3906 toc01
SUPPLY CURRENT
vs. TEMPERATURE
DS3906 toc02
SUPPLY CURRENT
vs. SCL FREQUENCY
180
160
SUPPLY CURRENT (µA)
DS3902 toc03
200
180
160
SUPPLY CURRENT (µA)
140
120
100
80
60
40
20
0
2.70
3.20
3.70
4.20
4.70
5.20
SUPPLY VOLTAGE (V)
180
160
SUPPLY CURRENT (µA)
140
120
100
80
60
40
20
0
-40
-15
10
35
60
SDA/SCL = V
CC
ADDRESS PINS
CONNECTED TO GND
V
CC
= 3.3V
V
CC
= 5V
200
140
120
100
80
60
40
20
0
V
CC
= SDA = 5V
ADDRESS PINS
CONNECTED TO GND
0
50
100 150 200 250 300 350 400
SCL FREQUENCY (kHz)
85
TEMPERATURE (°C)
RESISTORS (R
0,1
)
vs. RESISTOR SETTING
DS3906 toc04
RESISTOR R
2
vs. RESISTOR SETTING
DS3906 toc05
RESISTANCE (R
0,1
R
EXT
)
vs. RESISTOR SETTING
80
RESISTANCE (R
0,1
R
EXT
) (Ω)
70
60
50
40
30
20
10
0
R
EXT
= 87Ω
DS3906 toc06
3000
2500
RESISTORS (R
0,1
) (Ω)
2000
1500
1000
500
0
0
10
50
RESISTOR SETTING (dec)
20
30
40
60
1600
1400
1200
RESISTOR (R
2
) (Ω)
1000
800
600
400
200
0
90
70
0
10
50
RESISTOR SETTING (dec)
20
30
40
60
70
0
10
50
30
20
40
RESISTOR SETTING (dec)
60
70
DS3906 toc07
RESISTANCE (R
2
R
EXT
) (Ω)
200
R
EXT
= 258Ω
150
200
150
100
50
0
-50
0
10
50
30
20
40
RESISTOR SETTING (dec)
60
-40°C TO +25°C
100
50
0
0
10
50
30
20
40
RESISTOR SETTING (dec)
60
70
70
4
_____________________________________________________________________
DS3906 toc08
250
RESISTOR R
0,1
TEMPERATURE COEFFICIENT (ppm/°C)
RESISTANCE (R
2
R
EXT
)
vs. RESISTOR SETTING
RESISTOR R
0,1
TEMPERATURE COEFFICIENT
(-40°C TO +25°C) vs. RESISTOR SETTING
250
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