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DS1857B-050+-DS1857E-050+
Dual Temperature-Controlled Resistors with External Temperature Input and Monitors
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
PARTTEMP RANGEPIN-PACKAGEDS1857E-050-40°C to +95°C16 TSSOP
DS1857E-050/T&R-40°C to +95°C16 TSSOP
(Tape-and-Reel)
DS1857B-050-40°C to +95°C16 Ball CSBGA
TOP VIEW
16-BALL CSBGA (4mm x 4mm)
1.0mm PITCH
16 TSSOP24
EXTTMPA0WPENRHIZ
MON2MON1L0GNDVCCSCLA1H0SDAA2
DS1857
SDA1
SCL
WPEN
RHIZ
GND
VCC
EXTTMP
MON2
MON1
Pin ConfigurationsDS1857
SDA1
0.1µF
SCL
A0**
A1**
A2**
WPEN
RHIZ
GND
VCC
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.
VCC
VCC
VCC = 3.3V
4.7kΩ4.7kΩ
2-WIRE
INTERFACE
GROUND TO
DISABLE WRITE
PROTECT
Typical Operating Circuit
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and Monitors
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSupply VoltageVCC(Note 1)+3.05.5V
Input Logic 1 (SDA, SCL, A2, A1, A0,
WPEN, RHIZ)VIH(Note 2)0.7 x VccVCC + 0.3V
Input Logic 0 (SDA, SCL, A2, A1, A0,
WPEN, RHIZ)VIL(Note 2)-0.30.3 x VCCV
Resistor Inputs (L0, L1, H0, H1)-0.3VCC + 0.3V
Resistor CurrentIRES-3+3mA
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.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSupply CurrentICC(Note 3)12mA
Input LeakageIIL-1+1µA
Input Current each I/O Pin0.4 x VCC < VI/O < 0.9 x VCC-10+10µA
VOL13mA sink current00.4Low-Level Output Voltage (SDA)VOL26mA sink current00.6V
Full-Scale Input (MON1, MON2)(Note 4)2.48752.50002.5125V
Full-Scale VCC Monitor(Note 5)6.52086.55366.5864V
I/O CapacitanceCI/O10pF
WPEN Pullup ResistorRWPEN4065100kΩ
RHIZ Pullup ResistorRRHIZ4065100kΩ
Digital Power-On ResetPOD1.02.2V
Analog Power-On ResetPOA2.02.6V
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
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSEXTTMP Input VoltageVEXTTMP1.779V
Conversion ResolutionΔVEXTTMP625µV
Conversion AccuracyVEXTTMP(Note 9)12.8mV
EXTERNAL TEMPERATURE(VCC= 3.0V to 5.5V, TA= -40°C to +95°C, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSInput ResolutionΔVMON610µV
Supply ResolutionΔVCC1.6mV
Input/Supply AccuracyACC0.250.5% FS
(full scale)
Update Rate for MON1, MON2,
Temp, or VCCtframe2030ms
ANALOG VOLTAGE MONITORING (VCC= 3.0V to 5.5V, TA= -40°C to +95°C, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSPosition 00h ResistanceTA = +25°C0.701.01.25kΩ
Position FFh ResistanceTA = +25°C405060kΩ
Absolute Linearity(Note 6)-2+2LSB
Relative Linearity(Note 7)-1+1LSB
Temperature Coefficient(Note 8)50ppm/°C
High-Z Resistor CurrentIRHIZRHIZ = VCC0.1µA
ANALOGRESISTOR CHARACTERISTICS(VCC= 3.0V to 5.5V, TA= -40°C to +95°C, unless otherwise noted.)
DS1857
Dual Temperature-Controlled Resistors withExternal Temperature Input and Monitors
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSFast mode (Note 10)0400SCL Clock FrequencyfSCLStandard mode (Note 10)0100kHz
Fast mode (Note 10)1.3Bus Free Time Between STOP and
START ConditiontBUFStandard mode (Note 10)4.7µs
Fast mode (Notes 10, 11)0.6Hold Time (Repeated)
START ConditiontHD:STAStandard mode (Notes 10, 11)4.0µs
Fast mode (Note 10)1.3Low Period of SCL ClocktLOWStandard mode (Note 10)4.7µs
Fast mode (Note 10)0.6High Period of SCL ClocktHIGHStandard mode (Note 10)4.0µs
Fast mode (Notes 10, 12, 13)00.9Data Hold TimetHD:DATStandard mode (Notes 10, 12, 13)0µs
Fast mode (Note 10)100Data Setup TimetSU:DATStandard mode (Note 10)250ns
Fast mode (Note 10)0.6Start Setup TimetSU:STAStandard mode (Note 10)4.7µs
Fast mode (Note 13)20 + 0.1CB300Rise Time of Both SDA and SCL
SignalstFStandard mode (Note 13)20 + 0.1CB1000ns
Fast mode (Note 13)20 + 0.1CB300Fall Time of Both SDA and SCL
SignalstRStandard mode (Note 13)20 + 0.1CB300ns
Fast mode0.6Setup Time for STOP ConditiontSU:STOStandard mode4.0µs
Capacitive Load for Each Bus LineCB(Note 13)400pF
EEPROM Write TimetW(Note 14)10ms
ELECTRICAL CHARACTERISTICS(VCC= 3.0V to 5.5V, TA= -40°C to +95°C, 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 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.)
SUPPLY CURRENT vs. TEMPERATUREDS1857 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (6040200-20
SUPPLY CURRENT vs. VOLTAGE
DS1857 toc02
VOLTAGE (V)
SUPPLY CURRENT (
RESISTANCE vs. SETTING
DS1857 toc03
SETTING
RESISTANCE (k
ACTIVE SUPPLY CURRENT
vs. SCL FREQUENCY
DS1857 toc04
SCL FREQUENCY (kHz)
ACTIVE SUPPLY CURRENT (
SDA = 5V
