SNAS648C October   2014  – February 2023 TDC1000

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information (1)
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Transmitter Signal Path
      2. 8.3.2 Receiver Signal Path
      3. 8.3.3 Low Noise Amplifier (LNA)
      4. 8.3.4 Programmable Gain Amplifier (PGA)
      5. 8.3.5 Receiver Filters
      6. 8.3.6 Comparators for STOP Pulse Generation
        1. 8.3.6.1 Threshold Detector and DAC
        2. 8.3.6.2 Zero-Cross Detect Comparator
        3. 8.3.6.3 Event Manager
      7. 8.3.7 Common-Mode Buffer (VCOM)
      8. 8.3.8 Temperature Sensor
        1. 8.3.8.1 Temperature Measurement With Multiple RTDs
        2. 8.3.8.2 Temperature Measurement With a Single RTD
    4. 8.4 Device Functional Modes
      1. 8.4.1 Time-of-Flight Measurement Mode
        1. 8.4.1.1 Mode 0
        2. 8.4.1.2 Mode 1
        3. 8.4.1.3 Mode 2
      2. 8.4.2 State Machine
      3. 8.4.3 TRANSMIT Operation
        1. 8.4.3.1 Transmission Pulse Count
        2. 8.4.3.2 TX 180° Pulse Shift
        3. 8.4.3.3 Transmitter Damping
      4. 8.4.4 RECEIVE Operation
        1. 8.4.4.1 Single Echo Receive Mode
        2. 8.4.4.2 Multiple Echo Receive Mode
      5. 8.4.5 Timing
        1. 8.4.5.1 Timing Control and Frequency Scaling (CLKIN)
        2. 8.4.5.2 TX/RX Measurement Sequencing and Timing
      6. 8.4.6 Time-of-Flight (TOF) Control
        1. 8.4.6.1 Short TOF Measurement
        2. 8.4.6.2 Standard TOF Measurement
        3. 8.4.6.3 Standard TOF Measurement With Power Blanking
        4. 8.4.6.4 Common-Mode Reference Settling Time
        5. 8.4.6.5 TOF Measurement Interval
      7. 8.4.7 Averaging and Channel Selection
      8. 8.4.8 Error Reporting
    5. 8.5 Programming
      1. 8.5.1 Serial Peripheral Interface (SPI)
        1. 8.5.1.1 Chip Select Bar (CSB)
        2. 8.5.1.2 Serial Clock (SCLK)
        3. 8.5.1.3 Serial Data Input (SDI)
        4. 8.5.1.4 Serial Data Output (SDO)
    6. 8.6 Register Maps
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Level and Fluid Identification Measurements
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Level Measurements
          2. 9.2.1.2.2 Fluid Identification
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Water Flow Metering
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Regulations and Accuracy
          2. 9.2.2.2.2 Transit-Time in Ultrasonic Flow Meters
          3. 9.2.2.2.3 ΔTOF Accuracy Requirement Calculation
          4. 9.2.2.2.4 Operation
        3. 9.2.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

6.5 Electrical Characteristics

The electrical ratings specified in this section apply to all specifications in this document, unless otherwise noted. These specifications are interpreted as conditions that do not degrade the device parametric or functional specifications for the life of the product containing it. TA = 25°C, VDD = VIO = 3.7 V, VCOM = VCM = VDD / 2, CVCOM = 10 nF (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
TRANSMITTER SIGNAL PATH (TX)
VOUT(TX) Output voltage swing ƒout = 1 MHz, RL = 75 Ω to VCM HIGH VDD – 0.32 V
LOW 0.32 V
IOUT(TX) Output drive current ƒout = 1 MHz, RL = 75 Ω to VCM 22 mARMS
ƒOUT(TX) Output TX frequency ƒCLKIN = 8 MHz, divide-by-2 (programmable; see GUID-CA8C83E2-9C78-4A74-B4F4-8B498F851ABD.html#TITLE-SNAS648SNAS6482450) 4 MHz
RECEIVER SIGNAL PATH (RX)
ΔtSTOP STOP cycle-to-cycle jitter LNA capacitive feedback, GPGA = 6 dB, ƒIN = 1 MHz, VIN = 100 mVPP, CVCOM = 1 µF and GUID-72D520D8-3AB2-4ABC-B20F-282E41D31FC0.html#SNAS6485768 50 psRMS
LNA
GLNA LNA gain Capacitive feedback, CIN = 300 pF, ƒIN = 1 MHz, RL = 100 kΩ to VCM, CVCOM = 1 µF 20 dB
enLNA LNA input referred noise density Capacitive feedback, CIN = 300 pF, ƒ = 1 MHz, VDD = 3.1 V, VIN = VCM, RL = ∞, CVCOM = 1 µF 2 nV/√Hz
VIN(LNA) Input voltage range Resistive feedback, RL = 1 kΩ to VCM, CVCOM = 1 µF HIGH VCM + (VCM – 0.24) / (GLNA) V
LOW VCM – (VCM – 0.24) / (GLNA) V
VOUT(LNA) Output voltage range Resistive feedback, RL = 1 kΩ to VCM, CVCOM = 1 µF HIGH VDD – 0.24 V
LOW GND + 0.24 V
SRLNA Slew rate#SNAS6485249 Resistive feedback, RL = 1 kΩ to VCM, 100mV step, CVCOM = 1 µF 9 V/μs
XTK MUX ch-to-ch crosstalk Capacitive feedback, ƒ = 1 MHz, RL = 100 kΩ to VCM, CVCOM = 1 µF –57 dB
BWLNA –3-dB bandwidth Capacitive feedback, CIN = 300 pF, RL= 100 kΩ to VCM, CVCOM = 1 µF 5 MHz
VOS(LNA) LNA input offset voltage Resistive mode, VIN = VCM, RL = ∞ ±320 µV
VCOM
VCOM VCOM output voltage CVCOM = 1 µF VCM V
VCOM output error 0.5%
PGA
VIN(PGA) PGA input range  RL = 100 kΩ to VCM, CL = 10 pF to GND HIGH VCM + (VCM – 0.06) / (GPGA) V
LOW VCM – (VCM – 0.06) / (GPGA) V
GPGAMIN PGA min gain DC, RL = ∞, CL = 10 pF 0 dB
GPGAMAX PGA max gain 21 dB
ΔGPGA PGA gain step size 3 dB
GE(PGA) PGA gain error DC, GPGA = 0 dB, RL = ∞, CL = 10 pF 5%
TCGPGA PGA gain temperature coefficient DC, GPGA = 0 dB, RL = ∞, CL = 10 pF 170 ppm/°C
enPGA PGA input referred noise density GPGA = 21 dB, ƒ = 1 MHz, VDD = 3.1V, VIN = VCM, RL = ∞, CVCOM = 1 µF 3.1 nV/√Hz
VOUT(PGA) Output range RL = 100 kΩ to VCM, CL = 10 pF to GND HIGH VDD – 0.06 V
LOW 60 mV
BWPGA –3-db bandwidth GPGA = 21 dB, RL = 100 kΩ to VCM, CL = 10 pF, CVCOM = 1 µF 5 MHz
SRPGA Slew rate#SNAS6485249 GPGA = 21 dB, RL = 100 kΩ to VCM, CL = 10 pF, CVCOM = 1 µF 12.5 V/µs
ZERO CROSS COMPARATOR
VOS(COMP) Input offset voltage#SNAS6487393 Referred to VCOM ±115 µV
enCOMP Zero crossing comparator input referred noise#SNAS6487393  1 MHz 5 nV/√Hz
HYSTCOMP Hysteresis #SNAS6487393 Referred to VCOM -10 mV
THRESHOLD DETECTOR
VTHDET Threshold level ECHO_QUAL_THLD = 0h, VCOM referred –35 mV
ECHO_QUAL_THLD = 7h, VCOM referred –1.5 V
TEMPERATURE SENSOR INTERFACE#SNAS6488572
TERROR Temperature measurement accuracy RREF = 1 kΩ, PT1000 range: –40 to 125°C#SNAS6484309 1 °C
RREF = 1 kΩ, PT1000 range: –15°C to 85°C#SNAS6484309 0.5 °C
Relative accuracy RREF = 1 kΩ, RRTD1 = RRTD2 = 1.1 kΩ 0.02  °CRMS
TGE Gain error 5.8 m°C/°C 
POWER SUPPLY
IDD VDD supply current Sleep (EN = CLKIN = TRIGGER = low) 0.61 µA
Continuous receive mode, LNA and PGA bypassed 2.8 3 mA
Continuous receive mode, LNA and PGA active 6.2 7.5 mA
Temp. measurement only (PT1000 mode)#SNAS6489855 370 400 µA
Temp. measurement (PT500 mode)#SNAS6486279 500 540 µA
IIO VIO supply sleep current#SNAS6487393 Sleep (EN = CLKIN = TRIGGER = low) 2 nA
DIGITAL INPUT/OUTPUT CHARACTERISTICS
VIL Input logic low threshold 0.2 × VIO V
VIH Input logic high threshold 0.8 × VIO V
VOL Output logic low threshold SDO pin, 100-μA current 0.2 V
SDO pin, 1.85-mA current 0.4 V
START and STOP pins, 100-μA current 0.5 V
START and STOP pins, 1.85-mA current 0.6 V
ERRB pin, 100-μA current 0.2 V
ERRB pin, 1.85-mA current 0.4 V
VOH Output logic high threshold SDO pin, 100-μA current VIO – 0.2 V
SDO pin, 1.85-mA current VIO – 0.6 V
START and STOP pins, 100-μA current VIO – 0.5 V
START and STOP pins, 1.85-mA current VIO – 0.6 V
ERRB pin, 0-µA current VIO – 0.2 V
IOMAX Maximum output current for SDO, START and STOP 1.85 mA
(1) With ideal external components. For more detail see Temp Sensor Measurement section.
(2) PT1000 RTD approximate resistance: 800 Ω ≡ –52°C, 931 Ω ≡ –18°C, 1.10 kΩ ≡ 26°C, 1.33 kΩ ≡ 86°C and 1.48 kΩ ≡ 125°C.
(3) Specified currents include 120μA which flows through the RTD sensor in PT1000 mode (TEMP_RTD_SEL = 0).
(4) Specified currents include 240μA which flows through the RTD sensor in PT500 mode (TEMP_RTD_SEL = 1).
(5) Specified by design.
(6) The slew rate is measured from 10% to 90% and is represented by the average of the rising and falling slew rates.