LTC2157-12/ LTC2156-12/LTC2155-12 INTERNAL REFERENCE CHARACTERISTICSThe l denotes the specifications which apply over thefull operating temperature range, otherwise specifications are at TA = 25°C. (Note 5)PARAMETERCONDITIONSMINTYPMAXUNITS VCM Output Voltage IOUT = 0 0.435 • VDD – 18mV 0.435 • VDD 0.435 • VDD + 18mV V VCM Output Temperature Drift ±37 ppm/°C VCM Output Resistance –1mA < IOUT < 1mA 4 Ω VREF Output Voltage IOUT = 0 1.225 1.250 1.275 V VREF Output Temperature Drift ±30 ppm/°C VREF Output Resistance –400µA < IOUT < 1mA 7 Ω VREF Line Regulation 1.7V < VDD < 1.9V 0.6 mV/V POWER REQUIREMENTSThe l denotes the specifications which apply over the full operating temperaturerange, otherwise specifications are at TA = 25°C. (Note 5)LTC2157-12LTC2156-12LTC2155-12SYMBOL PARAMETERCONDITIONSMINTYPMAXMINTYPMAXMINTYPMAXUNITS VDD Analog Supply Voltage (Note 9) l 1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.9 V OVDD Output Supply Voltage (Note 9) l 1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.9 V IVDD Analog Supply Current l 309 345 291 320 266 295 mA IOVDD Digital Supply Current 1.75mA LVDS Mode l 40 46 38 45 37 42 mA 3.5mA LVDS Mode l 68 76 66 75 65 74 mA PDISS Power Dissipation 1.75mA LVDS Mode l 628 704 592 657 545 607 mW 3.5mA LVDS Mode l 679 758 643 711 596 665 mW PSLEEP Sleep Mode Power Clock Disabled <5 <5 <5 mW Clocked at fS(MAX) <5 <5 <5 mW PNAP Nap Mode Power Clocked at fS(MAX) 181 168 154 mW DIGITAL INPUTS AND OUTPUTSThe l denotes the specifications which apply over the full operatingtemperature range, otherwise specifications are at TA = 25°C. (Note 5)SYMBOL PARAMETERCONDITIONSMINTYPMAXUNITSENCODE INPUTS (ENC+, ENC– ) VID Differential Input Voltage (Note 8) l 0.2 V VICM Common Mode Input Voltage Internally Set 1.2 V Externally Set (Note 8) l 1.1 1.5 V RIN Input Resistance (See Figure 2) 10 kΩ CIN Input Capacitance (Note 8) 2 pF DIGITAL INPUTS (CS, SDI, SCK) VIH High Level Input Voltage VDD = 1.8V l 1.3 V VIL Low Level Input Voltage VDD = 1.8V l 0.6 V IIN Input Current VIN = 0V to 3.6V l –10 10 µA CIN Input Capacitance (Note 8) 3 pF SDO OUTPUT (Open-Drain Output. Requires 2k Pull-Up Resistor if SDO Is Used) ROL Logic Low Output Resistance to GND VDD = 1.8V, SDO = 0V 200 Ω IOH Logic High Output Leakage Current SDO = 0V to 3.6V l –10 10 µA COUT Output Capacitance (Note 8) 4 pF 21576512fb 4 For more information www.linear.com/LTC2157-12 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Converter Characteristics Analog Input Dynamic Accuracy Internal Reference Characteristics Power Requirements Digital Inputs And Outputs Timing Characteristics Timing Diagrams Typical Performance Characteristics Pin Functions Functional Block Diagram Applications Information Related Parts