DS1857
Dual Temperature-Controlled Resistors with
External Temperature Input and Monitors
______________________________________________ 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.
General Description
The DS1857 dual temperature-controlled nonvolatile
(NV) variable resistors with external temperature input
and monitors consists of two 50k 256-position linear
variable resistors, two analog monitor inputs (MON1,
MON2), and an external temperature sensor input. The
device provides an ideal method for setting and tem-
perature-compensating bias voltages and currents in
control applications using minimal circuitry. The vari-
able resistor settings are stored in EEPROM memory
and can be accessed over the 2-wire serial bus.
Applications
Optical Transceivers
Optical Transponders
Instrumentation and Industrial Controls
RF Power Amps
Diagnostic Monitoring
Features
Four Total Monitored Channels (Temperature,
V
CC
, MON1, MON2)
Two External Analog Inputs (MON1, MON2)
Interface to External Temperature Sensor (LM50)
Two 50k, Linear, 256-Position, Nonvolatile
Temperature-Controlled Variable Resistors
Resistor Settings Changeable Every 2C
Access to Monitoring and ID Information
Configurable with Separate Device Addresses
Resistor Disable (Open-Circuit) Function
2-Wire Serial Interface
Three Address Lines for Multiple Devices
Operates from a 3.3V or 5V Supply
SFF-8472 Compatible
Ordering Information
Rev 1; 6/04
PART
TEMP RANGE
PIN-PACKAGE
DS1857E-050
-40C to +95C 16 TSSOP
DS1857E-050/T&R
-40C to +95C
16 TSSOP
(Tape-and-Reel)
DS1857B-050
-40C to +95C 16 Ball CSBGA
A
TOP VIEW
B
C
D
1
16-BALL CSBGA (4mm x 4mm)
1.0mm PITCH
16 TSSOP
3
2
4
EXTTMP
A0
WPEN
RHIZ
MON2
MON1
L0
GND
H1
V
CC
SCL
A1
L1
H0
SDA
A2
DS1857
SDA
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SCL
A0
A1
A2
WPEN
RHIZ
GND
V
CC
H1
L1
H0
L0
EXTTMP
MON2
MON1
Pin Configurations
DS1857
SDA
1
2
3
4
5
6
7
8
16
0.1F
15
14
13
12
11
10
9
SCL
A0**
A1**
A2**
WPEN
RHIZ
GND
V
CC
H1
L1
H0
L0
EXTTMP
MON2
MON1
Tx DISABLE
TO EXTERNAL TEMPERATURE
SENSOR, SUCH AS LM50
DIAGNOSTIC
INPUTS
0 TO 2.5V FS
TO LASER BIAS
CONTROL
TO LASER MODULATION
CONTROL
DECOUPLING
CAP
Rx POWER*
Tx BIAS*
*Rx POWER AND Tx BIAS CAN BE ARBITRARILY
ASSIGNED TO THE MON INPUTS.
**ADDRESS INPUTS DETERMINE THE MAIN DEVICE 2-WIRE
SLAVE ADDRESS WHEN ADFIX = 0. THIS ADDRESS MUST BE
DIFFERENT THAN THE AUX DEVICE ADDRESS WHEN ADEN = 0.
V
CC
V
CC
V
CC
= 3.3V
4.7k
4.7k
2-WIRE
INTERFACE
GROUND TO
DISABLE WRITE
PROTECT
Typical Operating Circuit
DS1857
Dual Temperature-Controlled Resistors with
External Temperature Input and Monitors
2
_____________________________________________________________________
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
V
CC
(Note 1)
+3.0
5.5
V
Input Logic 1 (SDA, SCL, A2, A1, A0,
WPEN, RHIZ)
V
IH
(Note 2)
0.7 x Vcc
V
CC
+ 0.3
V
Input Logic 0 (SDA, SCL, A2, A1, A0,
WPEN, RHIZ)
V
IL
(Note 2)
-0.3
0.3 x V
CC
V
Resistor Inputs (L0, L1, H0, H1)
-0.3
V
CC
+ 0.3
V
Resistor Current
I
RES
-3
+3
mA
ABSOLUTE MAXIMUM RATINGS
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 on V
CC
Relative to Ground.......................-0.5V to +6.0V
Voltage on Inputs Relative
to Ground* ................................................-0.5V to V
CC
+ 0.5V
Voltage on Resistor Inputs Relative
to Ground* ................................................-0.5V to V
CC
+ 0.5V
Current into Resistors............................................................5mA
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
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40C to +95C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current
I
CC
(Note 3)
1
2
mA
Input Leakage
I
IL
-1
+1
A
Input Current each I/O Pin
0.4 x V
CC
< V
I/O
< 0.9 x V
CC
-10
+10
A
V
OL1
3mA sink current
0
0.4
Low-Level Output Voltage (SDA)
V
OL2
6mA sink current
0
0.6
V
Full-Scale Input (MON1, MON2)
(Note 4)
2.4875
2.5000
2.5125
V
Full-Scale V
CC
Monitor
(Note 5)
6.5208
6.5536
6.5864
V
I/O Capacitance
C
I/O
10
pF
WPEN Pullup Resistor
R
WPEN
40
65
100
k
RHIZ Pullup Resistor
R
RHIZ
40
65
100
k
Digital Power-On Reset
POD
1.0
2.2
V
Analog Power-On Reset
POA
2.0
2.6
V
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 3.0V to 5.5V, T
A
= -40C to +95C, unless otherwise noted.)
*Not to exceed 6.0V.
DS1857
Dual Temperature-Controlled Resistors with
External Temperature Input and Monitors
_____________________________________________________________________
3
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
EXTTMP Input Voltage
V
EXTTMP
1.779
V
Conversion Resolution
V
EXTTMP
625
V
Conversion Accuracy
V
EXTTMP
(Note 9)
12.8
mV
EXTERNAL TEMPERATURE
(V
CC
= 3.0V to 5.5V, T
A
= -40C to +95C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Resolution
VMON
610
V
Supply Resolution
V
CC
1.6
mV
Input/Supply Accuracy
A
CC
0.25
0.5
% FS
(full scale)
Update Rate for MON1, MON2,
Temp, or V
CC
t
frame
20
30
ms
ANALOG VOLTAGE MONITORING
(V
CC
= 3.0V to 5.5V, T
A
= -40C to +95C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Position 00h Resistance
T
A
= +25C
0.70
1.0
1.25
k
Position FFh Resistance
T
A
= +25C
40
50
60
k
Absolute Linearity
(Note 6)
-2
+2
LSB
Relative Linearity
(Note 7)
-1
+1
LSB
Temperature Coefficient
(Note 8)
50
ppm/C
High-Z Resistor Current
I
RHIZ
R
HIZ
= V
CC
0.1
A
ANALOG RESISTOR CHARACTERISTICS
(V
CC
= 3.0V to 5.5V, T
A
= -40C to +95C, unless otherwise noted.)
DS1857
Dual Temperature-Controlled Resistors with
External Temperature Input and Monitors
4
_____________________________________________________________________
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Fast mode (Note 10)
0
400
SCL Clock Frequency
f
SCL
Standard mode (Note 10)
0
100
kHz
Fast mode (Note 10)
1.3
Bus Free Time Between STOP and
START Condition
t
BUF
Standard mode (Note 10)
4.7
s
Fast mode (Notes 10, 11)
0.6
Hold Time (Repeated)
START Condition
t
HD:STA
Standard mode (Notes 10, 11)
4.0
s
Fast mode (Note 10)
1.3
Low Period of SCL Clock
t
LOW
Standard mode (Note 10)
4.7
s
Fast mode (Note 10)
0.6
High Period of SCL Clock
t
HIGH
Standard mode (Note 10)
4.0
s
Fast mode (Notes 10, 12, 13)
0
0.9
Data Hold Time
t
HD:DAT
Standard mode (Notes 10, 12, 13)
0
s
Fast mode (Note 10)
100
Data Setup Time
t
SU:DAT
Standard mode (Note 10)
250
ns
Fast mode (Note 10)
0.6
Start Setup Time
t
SU:STA
Standard mode (Note 10)
4.7
s
Fast mode (Note 13)
20 + 0.1C
B
300
Rise Time of Both SDA and SCL
Signals
t
F
Standard mode (Note 13)
20 + 0.1C
B
1000
ns
Fast mode (Note 13)
20 + 0.1C
B
300
Fall Time of Both SDA and SCL
Signals
t
R
Standard mode (Note 13)
20 + 0.1C
B
300
ns
Fast mode
0.6
Setup Time for STOP Condition
t
SU:STO
Standard mode
4.0
s
Capacitive Load for Each Bus Line
C
B
(Note 13)
400
pF
EEPROM Write Time
t
W
(Note 14)
10
ms
AC ELECTRICAL CHARACTERISTICS
(V
CC
= 3.0V to 5.5V, T
A
= -40C to +95C, unless otherwise noted.)
Note 1: All voltages are referenced to ground.
Note 2: I/O pins of fast-mode devices must not obstruct the SDA and SCL lines if V
CC
is switched off. The address inputs should be
connected to either V
CC
or GND depending on the desired address setting.
Note 3: SDA and SCL are connected to V
CC
and all other input signals are connected to well-defined logic levels.
Note 4: The maximum voltage the MON inputs will read is approximately 2.5V, even if the voltage on the inputs is greater than 2.5V.
Note 5: This voltage is defining the maximum range of the analog-to-digital converter and not the maximum V
CC
voltage.
Note 6: Absolute linearity is the difference of measured value from expected value at DAC position. The expected value is a
straight line from measured minimum position to measured maximum position.
Note 7: Relative linearity is the deviation of an LSB DAC setting change vs. the expected LSB change. The expected LSB change
is the slope of the straight line from measured minimum position to measured maximum position.
Note 8: See the Typical Operating Characteristics.
Note 9: The conversion accuracy does not include any error from the LM50.
Note 10: A fast-mode device can be used in a standard-mode system, but the requirement t
SU:DAT
> 250ns must then be met. This
is automatically the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the
LOW period of the SCL signal, it must output the next data bit to the SDA line t
RMAX
+ t
SU:DAT
= 1000ns + 250ns = 1250ns
before the SCL line is released.
DS1857
Dual Temperature-Controlled Resistors with
External Temperature Input and Monitors
_____________________________________________________________________
5
AC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 3.0V to 5.5V, T
A
= -40C to +95C, unless otherwise noted.)
Note 11: After this period, the first clock pulse is generated.
Note 12: The maximum t
HD:DAT
only to has be met if the device does not stretch the LOW period (t
LOW
) of the SCL signal.
Note 13: A device must internally provide a hold time of at least 300ns for the SDA signal (see the V
IH MIN
of the SCL signal) in order
to bridge the undefined region of the falling edge of SCL.
Note 14: C
B
--total capacitance of one bus line, timing referenced to 0.9 x V
CC
and 0.1 x V
CC
.
Note 15: EEPROM write begins after a STOP condition occurs.
Typical Operating Characteristics
(V
CC
= 5.0V, T
A
= +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
DS1857 toc01
TEMPERATURE (C)
SUPPLY CURRENT (
A)
80
60
40
20
0
-20
540
580
620
660
700
500
-40
100
SUPPLY CURRENT vs. VOLTAGE
DS1857 toc02
VOLTAGE (V)
SUPPLY CURRENT (
A)
5.0
4.5
4.0
3.5
450
500
550
600
650
700
400
3.0
5.5
RESISTANCE vs. SETTING
DS1857 toc03
SETTING
RESISTANCE (k
)
250
200
150
100
50
10
20
30
40
50
60
0
0
300
ACTIVE SUPPLY CURRENT
vs. SCL FREQUENCY
DS1857 toc04
SCL FREQUENCY (kHz)
ACTIVE SUPPLY CURRENT (
A)
300
200
100
540
580
620
660
700
500
0
400
SDA = 5V
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