General Description
The DS3902 features a dual, nonvolatile (NV), low tem-
perature-coefficient, variable digital resistor with 256
user-selectable positions. The DS3902 can operate
over a wide supply range of 2.4V to 5.5V, and commu-
nication with the device is achieved through an I
2
CTM-
compatible serial interface. Internal address settings
allow the DS3902 slave address to be programmed to
one of 128 possible addresses. The low cost and the
small size of the DS3902 make it an ideal replacement
for conventional mechanical-trimming resistors.
Applications
Optical Transceivers
Optical Transponders
Instrumentation and Industrial Controls
RF Power Amps
Audio Power-Amp Biasing
Replacement for Mechanical Variable Resistors
and DIP Switches
Features
Dual 256-Position Linear Digital Resistors
Available as 50k/30k or 50k/15k
Resistor Settings Stored in NV Memory
Low Temperature Coefficient
I
2
C-Compatible Serial Interface
Wide Operating Voltage (2.4V to 5.5V)
Software Write Protection
User-EEPROM Memory
Programmable Slave Address
Operating Temperature Range: -40C to +95C
Small 8-Pin SOP Package
DS3902
Dual, NV, Variable Resistors
with User EEPROM
______________________________________________ Maxim Integrated Products
1
SCL
SDA
ADD_SEL
1
GND
2-WIRE
MASTER
4.7k
4.7k
0.1
F
H1
H0
V
CC
V
CC
V
CC
V
CC
OUT-
OUT+
BIAS+
BIAS-
MD
IN+
IN-
TX_FAULT
TX_DISABLE
BIASMAX
2
APCSET
2
MODSET
2
PC_MON
BS_MON
BIAS SET
MOD SET
NOTES:
1. WITH ADD_SEL TIED TO GND, THE SLAVE ADDRESS WILL BE A2H.
2. FOR A DETAILED APPLICATION DIAGRAM OF A SPECIFIC LD,
CONSULT THE LASER DRIVER DATA SHEET.
LASER
DRIVER IC
DS3902
Typical Operating Circuit
Rev 0; 5/04
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.
*Add /T&R for Tape & Reel orders.
Ordering Information
Pin Configuration appears at end of data sheet.
PART
RESISTOR
VALUES
(R0, R1)
TOP
BRAND
PIN-
PACKAGE
DS3902U-530
30k
, 50k
3902A
8 SOP
DS3902U-515
15k
, 50k
3902B
8 SOP
I
2
C is a trademark of Philips Corp. Purchase of I
2
C components of Maxim Integrated Products, Inc., or one of its Associated
Companies, conveys a license under the Philips I
2
C Patent Rights to use these components in an I
2
C system, provided that the sys-
tem conforms to the I
2
C Standard Specification as defined by Philips.
DS3902
Dual, NV, Variable Resistors
with User EEPROM
2
_____________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40C to +95C)
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.
Voltage Range on V
CC
, SDA, SCL, H0,
and H1 Relative to Ground................................-0.5V to +6.0V
Voltage Range on ADD_SEL Relative
to Ground ...............-0.5V to (V
CC
+ 0.5V), not to exceed 6.0V
Resistor Current ....................................................................3mA
Operating Temperature Range ...........................-40C to +95C
Programming Temperature Range .........................0C to +70C
Storage Temperature Range .............................-55C to +125C
Soldering Temperature ...............................................See IPC/JEDEC
J-STD-020A Specification
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
V
CC
(Note 1)
+2.4
+5.5
V
Input Logic 1
(SDA, SCL, ADD_SEL)
V
IH
0.7 x
V
CC
V
CC
+
0.3
V
Input Logic 0
(SDA, SCL, ADD_SEL)
V
IL
-0.3
+0.3 x
V
CC
V
Resistor Inputs
H0, H1
-0.3
+5.5
V
Resistor Current
I
RES
3
mA
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +2.4V to +5.5V, T
A
= -40C to +95C, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Standby Current
I
STBY
(Note 2)
200
A
Input Leakage
I
L
-1
+1
A
V
OL1
3mA sink current
0
0.4
Low-Level Output Voltage (SDA)
V
OL2
6mA sink current
0
0.6
V
ANALOG RESISTOR CHARACTERISTICS
(V
CC
= +2.4V to +5.5V, T
A
= -40C to +95C, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Resistance Tolerance
T
A
= +25C
-20
+20
%
Position 0 Resistance
160
250
Absolute Linearity
(Note 3)
-1
+1
LSB
Relative Linearity
(Note 4)
-0.75
+0.75
LSB
Temperature Coefficient
At position FFh. (Notes 5, 6)
-300
+300
ppm/C
High-Impedance Resistor Current
I
RHIZ
H0, H1 = V
CC
-1
+1
A
DS3902
Dual, NV, Variable Resistors
with User EEPROM
_____________________________________________________________________
3
AC ELECTRICAL CHARACTERISTICS (Figure 1)
(V
CC
= +2.4V to +5.5V, T
A
= -40C to +95C, unless otherwise noted. Timing referenced to V
IL(MAX)
and V
IH(MIN)
.)
Note 1: All voltages referenced to ground.
Note 2: I
STBY
specified for the inactive state measured with SDA = SCL = V
CC
, ADD_SEL = GND, and with H0 and H1 floating.
Note 3: Absolute linearity is the difference of measured value from expected value at resistor position. Expected value is from the
measured minimum position to measured maximum position.
Note 4: Relative linearity is the deviation of an LSB resistor setting change vs. the expected LSB change. Expected LSB slope of the
straight line is the typical operating curves from the measured minimum position to measured maximum position.
Note 5: See the Typical Operating Characteristics section.
Note 6: Guaranteed by design.
Note 7: Timing shown is for fast-mode (400kHz) operation. This device is also backward-compatible with I
2
C standard mode.
Note 8: C
B
--total capacitance of one bus line in picofarads.
Note 9: EEPROM write begins after a STOP condition occurs.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SCL Clock Frequency
f
SCL
(Note 7)
0
400
kHz
Bus Free Time Between STOP
and START Conditions
t
BUF
1.3
s
Hold Time (Repeated)
START Condition
t
HD:STA
0.6
s
Low Period of SCL
t
LOW
1.3
s
High Period of SCL
t
HIGH
0.6
s
Data Hold Time
t
HD:DAT
0
0.9
s
Data Setup Time
t
SU:DAT
100
s
Start Setup Time
t
SU:STA
0.6
s
SDA and SCL Rise Time
t
R
(Note 8)
20 +
0.1 x C
B
300
ns
SDA and SCL Fall Time
t
F
(Note 8)
20 +
0.1 x C
B
300
ns
Stop Setup Time
t
SU:STO
0.6
s
SDA and SCL Capacitive Loading
C
B
(Note 8)
400
pF
EEPROM Write Time
t
WR
(Note 9)
10
ms
Input Capacitance
C
I
5
pF
Startup Time
t
ST
(Note 6)
2
ms
NONVOLATILE MEMORY CHARACTERISTICS
(VCC = +2.4V to +5.5V, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
EEPROM Writes
+70C (Note 6)
50,000
DS3902
Dual, NV, Variable Resistors
with User EEPROM
4
_____________________________________________________________________
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25C, unless otherwise noted.)
STANDBY SUPPLY CURRENT
vs. TEMPERATURE
DS3902 toc01
TEMPERATURE (
C)
STANDBY SUPPLY CURRENT (
A)
80
60
20
40
0
-20
20
40
60
80
100
120
140
160
180
0
-40
V
CC
= +5V
V
CC
= +3V
ASEL = GND
H0, H1, OPEN
SDA = SCL = V
CC
SUPPLY CURRENT
vs. SCL FREQUENCY
DS3902 toc02
SCL FREQUENCY (kHz)
SUPPLY CURRENT (
A)
350
300
200 250
100 150
50
20
40
60
80
100
120
140
160
180
200
0
0
400
V
CC
= SDA = +5V
RESISTANCE
vs. RESISTOR SETTING
DS3902 toc03
RESISTOR SETTING (DEC)
RESISTANCE (
)
250
225
175 200
50 75 100 125 150
25
5
10
15
20
25
30
35
40
45
50
0
0
H1
H0 (-530 VERSION)
TEMPERATURE COEFFICIENT
vs. POSITION
DS3902 toc04
POSITION (DEC)
TEMPERATURE COEFFICIENT (ppm/
C)
250
200
150
100
50
0
200
400
600
800
1000
1200
1400
1600
-200
0
TC OF +25
C TO -40C
TC OF +25
C TO +85C
POSITION FFh RESISTANCE PERCENT
CHANGE FROM +25
C vs. TEMPERATURE
DS3902 toc05
TEMPERATURE (
C)
RESISTANCE % CHANGE (FROM +25
C)
80
60
40
20
0
-20
0
0.2
0.4
0.6
0.8
-0.2
-40
POSITION 00h RESISTANCE PERCENT
CHANGE FROM +25
C vs. TEMPERATURE
DS3902 toc06
TEMPERATURE (
C)
RESISTANCE % CHANGE (FROM +25
C)
80
60
20
40
0
-20
-8
-6
-4
-2
0
2
4
6
8
10
12
-10
-40
H0, H1 RESISTANCE
vs. POWER-UP VOLTAGE
DS3902 toc07
POWER-UP VOLTAGE (V)
RESISTANCE (
)
5
4
3
2
1
10
20
30
40
50
60
70
80
90
100
0
0
H0 (-530 VERSION)
EEPROM RECALL
>100k
H1
PROGRAMMED
RESISTANCE (FFh)
H0, H1 RESISTANCE
vs. POWER-DOWN VOLTAGE
DS3902 toc08
POWER-DOWN VOLTAGE (V)
RESISTANCE (
)
5
4
3
2
1
10
20
30
40
50
60
70
80
90
100
0
0
H0 (-530 VERSION)
>100k
H1
PROGRAMMED
RESISTANCE (FFh)
POSITION 7Fh RESISTANCE
vs. SUPPLY VOLTAGE
DS3902 toc09
SUPPLY VOLTAGE (V)
POSITION 7Fh RESISTANCE (
)
5.4
4.9
3.9
4.4
3.4
2.9
12
14
16
18
20
22
24
26
28
30
10
2.4
H1
H0 (-530 VERSION)
DS3902
Dual, NV, Variable Resistors
with User EEPROM
_____________________________________________________________________
5
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, T
A
= +25C, unless otherwise noted.)
H0 ABSOLUTE LINEARITY
vs. POSITION
DS3902 toc10
POSITION (DEC)
H0 ABSOLUTE LINEARITY (LSB)
250
200
150
100
50
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0
0
H0 RELATIVE LINEARITY
vs. POSITION
DS3902 toc11
POSITION (DEC)
H0 RELATIVE LINEARITY (LSB)
250
200
150
100
50
0.02
0.04
0.06
0.08
0.1
0
0
H1 ABSOLUTE LINEARITY
vs. POSITION
DS3902 toc12
POSITION (DEC)
H1 ABSOLUTE LINEARITY (LSB)
250
200
150
100
50
0.02
0.04
0.06
0.08
0.1
0
0
H1 RELATIVE LINEARITY
vs. POSITION
DS3902 toc13
POSITION (DEC)
H1 RELATIVE LINEARITY (LSB)
250
200
150
100
50
0.02
0.04
0.06
0.08
0.1
0
0
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