SBOS301C May   2004  – December 2025 LOG114

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics (±5V)
    6. 5.6 Electrical Characteristics (5V)
    7. 5.7 Typical Characteristics: VS = ±5V
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Logarithmic and Difference Amplifier
      2. 6.3.2 COM Voltage Range
      3. 6.3.3 VCM IN
      4. 6.3.4 Auxiliary Operational Amplifier
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Applications Information
      1. 7.1.1 Transfer Function
      2. 7.1.2 Input Current Range
      3. 7.1.3 Setting the Reference Current
      4. 7.1.4 Negative Input Currents
      5. 7.1.5 Voltage Inputs
      6. 7.1.6 High-Current Linearity Correction
      7. 7.1.7 Error Sources
        1. 7.1.7.1 Accuracy
        2. 7.1.7.2 Total Error
        3. 7.1.7.3 Errors RTO and RTI
        4. 7.1.7.4 Log Conformity
        5. 7.1.7.5 Individual Error Components
    2. 7.2 Typical Applications
      1. 7.2.1 Design Example for Dual-Supply Configuration
      2. 7.2.2 Design Example for Single-Supply Configuration
      3. 7.2.3 Advantages of Dual−Supply Operation
      4. 7.2.4 Log Ratio
      5. 7.2.5 Data Compression
      6. 7.2.6 3.3V Operation
      7. 7.2.7 Erbium-Doped Fiber Optic Amplifier (EDFA)
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Device Nomenclature
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
      2. 8.2.2 PSpice® for TI
      3. 8.2.3 TINA-TI™ (Free Software Download)
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

5.6 Electrical Characteristics (5V)

at TA = 25°C, VS = 5V, VLOGOUT RL = 10kΩ, VCM = GND, all chips site origins (CSO), unless otherwise noted.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
CORE LOG FUNCTION
Core log function IIN/VOUT Equation  VO = (0.375) log (I1/I2)+VCM V
LOG CONFORMITY ERROR
Log conformity error(1) 1nA to 100µA (5 decades) 0.1 0.3 %
0.009 0.026 dB
TA = -5℃ to 75℃ 0.1 0.4 %
100pA to 3.5mA (7.5 decades) 2.2 %
0.19 dB
TA = -5℃ to 75℃ 2.3 %
1mA to 10mA See typical characteristics
TA = -5℃ to 75℃ See typical characteristics
TRANSFER FUNCTION (GAIN)
Initial scaling factor 100pA to 10mA 0.375 V/decade
Scaling factor error(2) 1nA to 100µA 0.4 ±2.5 %
0.035 0.21 dB
TA = –5°C to 75°C 1.5 ±3.5 %
TA = 15°C to 50°C 0.7 ±3 %
INPUT, A1 and A2
VOS Offset voltage   ±1 ±7 mV
dVOS/dT Offset voltage vs temperature TA = -5℃ to 75℃ ±30 µV/℃
PSRR Offset voltage vs power supply VS = 4.5V to 5.5V 300 µV/V
IB Input bias current ±5 pA
TA = -5℃ to 75℃ Doubles every 10℃
VCM Input common-mode range (V–) + 1.5V (V+) – 1.5 V
en Voltage noise f = 0.1Hz to 10kHz 3 µVrms
f = 1kHz 30 nV/√Hz
in Current noise f = 1kHz 4 fA/√Hz
OUTPUT, A3 (VLOGOUT)
VOSO Output offset voltage ±14 ±65 mV
TA = -5℃ to 75℃ ±18 ±80 mV
FSO Full-scale output(3) (V–) + 0.6 (V+) – 0.6 V
GBW Gain bandwidth product IIN = 1µA 50 MHz
ISC Short-circuit current ±18 mA
Capacitive load 100 pF
OP AMP, A4 and A5
VOS Input offset voltage ±250 ±4000 µV
dVOS/dT Input offset voltage vs temperature TA = -5℃ to 75℃   ±2 µV/℃
PSRR Input offset voltage vs supply Vs = 4.8V to 5.5V   30 µV/V
CMRR Input offset voltage vs common-mode voltage 70 dB
IB Input bias current –1 µA
IOS Input offset current ±0.05 µA
Input voltage range (V–) (V+) – 1.5V V
Input voltage noise f = 0.1Hz to 10kHz 1 µVpp
f = 1kHz   28   nV/√Hz
in Current noise f = 1kHz   2   pA/√Hz
AOL Open-loop voltage gain 100 dB
GBW Gain-bandwidth product  CSO: SHE 15 MHz
CSO:TID 60
SR Slew rate  CSO: SHE 5 V/μs
CSO:TID 22
tS Settling time 0.01% G = -1, 3V step, CL = 100pF 1.5 µs
Rated output (V–) + 0.5V (V+) – 0.5V V
ISC Short-circuit current  Sourcing  CSO: SHE +4 mA
CSO: TID +20
Sinking CSO: SHE –10
CSO: TID -20
TOTAL ERROR
Total error(4)(5) See typical characteristics
FREQUENCY RESPONSE, Core Log
BW, 3 dB, I1 or I2(6) IAC = 10% of IDC value, IREF = 1µA 1nA 5 kHz
10nA 12
100nA 120
1µA 2.3 MHz
10µA to 10mA (ratio 1:1k) > 5
Step response, I1 or I2(6)  8nA to 240nA (ratio 1:30)   Increasing, IREF = 1µA 0.8 µs
Decreasing, IREF = 1µA CSO: SHE 4
CSO: TID 7.6
10nA to 100nA (ratio 1:10)   Increasing, IREF = 1µA 1.5
Decreasing, IREF = 1µA CSO: SHE 4
CSO: TID 5
10nA to 1µA (ratio 1:100)   Increasing, IREF = 1µA 0.25
Decreasing, IREF = 1µA CSO: SHE 4
CSO: TID 6
1mA to 10mA (ratio 1:10)  Increasing, IREF = 1µA 1
Decreasing, IREF = 1µA 1
VOLTAGE REFERENCE
Bandgap voltage 2.5 V
Error ±0.15 ±1 %
TA = -5℃ to 75℃ ±25 ppm/℃
VS = 4.8V to 11V ±30 ppm/V
IO = ±2mA ±200 ppm/mA
ISC Short-circuit current ±10 mA
POWER SUPPLY
IQ Quiescent current  IO = 0 CSO: SHE ±10 ±15 mA
CSO: TID ±6.3 ±15
(1) Log conformity error is peak deviation from the best-fit straight line of VO vs Log (I1/I2) curve expressed as a percent of peak-to-peak full-scale output. Scale factor, K, equals 0.375V output per decade of input current.
(2) Scale factor of core log function is trimmed to 0.375V output per decade change of input current.
(3) Specified by design.
(4) Worst-case total error for any ratio of I1/I2, as the largest of the two errors, when I, and I2 are considered separately
(5) Total error includes offset voltage, bias current, gain, and log conformity.
(6) Small signal bandwidth (3dB) and transient response are a function of the level of input current. Smaller input current amplitude results in lower bandwidth.