DS1857B-050 ,3.3 V or 5 V, dual temperature-controlled resistor with external temperature input and monitorApplications♦ SFF-8472 CompatibleOptical TransceiversOptical TranspondersOrdering InformationInstru ..
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DS1857B-050-DS1857E-050
3.3 V or 5 V, dual temperature-controlled resistor with external temperature input and monitor
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and Monitors
General DescriptionThe DS1857 dual temperature-controlled nonvolatile
(NV) variable resistors with external temperature input
and monitors consists of two 50kΩ256-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.
ApplicationsOptical Transceivers
Optical Transponders
Instrumentation and Industrial Controls
RF Power Amps
Diagnostic Monitoring
FeaturesFour Total Monitored Channels (Temperature,
VCC, MON1, MON2)Two External Analog Inputs (MON1, MON2)Interface to External Temperature Sensor (LM50)Two 50kΩ, Linear, 256-Position, Nonvolatile
Temperature-Controlled Variable ResistorsResistor Settings Changeable Every 2°CAccess to Monitoring and ID Information
Configurable with Separate Device AddressesResistor Disable (Open-Circuit) Function2-Wire Serial InterfaceThree Address Lines for Multiple DevicesOperates from a 3.3V or 5V SupplySFF-8472 Compatible
Ordering InformationRev 1; 6/04
Pin Configurations
Typical Operating Circuit
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and Monitors
ABSOLUTE MAXIMUM RATINGSStresses 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 VCCRelative to Ground.......................-0.5V to +6.0V
Voltage on Inputs Relative
to Ground*................................................-0.5V to VCC+ 0.5V
Voltage on Resistor Inputs Relative
to Ground*................................................-0.5V to VCC+ 0.5V
Current into Resistors............................................................5mA
Operating Temperature Range...........................-40°C to +95°C
Programming Temperature Range.........................0°C to +70°C
Storage Temperature Range.............................-55°C to +125°C
Soldering Temperature.......................................See IPC/JEDEC
J-STD-020A Specification
RECOMMENDED DC OPERATING CONDITIONS(TA= -40°C to +95°C, unless otherwise noted.)
DC ELECTRICAL CHARACTERISTICS(VCC= 3.0V to 5.5V, TA= -40°C to +95°C, unless otherwise noted.)
*Not to exceed 6.0V.
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and Monitors
EXTERNAL TEMPERATURE(VCC= 3.0V to 5.5V, TA= -40°C to +95°C, unless otherwise noted.)
ANALOG VOLTAGE MONITORING
ANALOGRESISTOR CHARACTERISTICS
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and MonitorsELECTRICAL CHARACTERISTICS
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 VCCis switched off. The address inputs should be
connected to either VCCor GND depending on the desired address setting.
Note 3:SDA and SCL are connected to VCCand 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 VCCvoltage.
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 tSU: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 tRMAX+ tSU:DAT= 1000ns + 250ns = 1250ns
before the SCL line is released.
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and MonitorsELECTRICAL CHARACTERISTICS (continued)(VCC= 3.0V to 5.5V, TA= -40°C to +95°C, unless otherwise noted.)
Note 11: After this period, the first clock pulse is generated.
Note 12: The maximum tHD:DATonly to has be met if the device does not stretch the LOW period (tLOW) of the SCL signal.
Note 13: A device must internally provide a hold time of at least 300ns for the SDA signal (see the VIH MIN of the SCL signal) in orderto bridge the undefined region of the falling edge of SCL.
Note 14: CB—total capacitance of one bus line, timing referenced to 0.9 x VCCand 0.1 x VCC.
Note 15: EEPROM write begins after a STOPcondition occurs.
Typical Operating Characteristics(VCC= 5.0V, TA= +25°C, unless otherwise noted.)
