SLOS985 June   2017 TLC2274M-MIL

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
    5. 6.5 TLC2274M-MIL Electrical Characteristics VDD = 5 V
    6. 6.6 TLC2274M-MIL Electrical Characteristics VDD± = ±5 V
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Macromodel Information
    2. 8.2 Typical Application
      1. 8.2.1 High-Side Current Monitor
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Differential Amplifier Equations
        3. 8.2.1.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 Macromodel Information

Macromodel information provided was derived using MicroSim Parts™, the model generation software used with MicroSim PSpice™. The Boyle macromodel , IEEE Journal of Solid-State Circuits, SC-9, 353 (1974). and subcircuit in Figure 53 were generated using the TLC2274M-MIL typical electrical and operating characteristics at TA = 25°C. Using this information, output simulations of the following key parameters can be generated to a tolerance of 20% (in most cases):

  • Maximum positive output voltage swing
  • Maximum negative output voltage swing
  • Slew rate
  • Quiescent power dissipation
  • Input bias current
  • Open-loop voltage amplification
  • Unity-gain frequency
  • Common-mode rejection ratio
  • Phase margin
  • DC output resistance
  • AC output resistance
  • Short-circuit output current limit

1. Macromodeling of Integrated Circuit Operational Amplifiers, IEEE Journal of Solid-State Circuits, SC-9, 353 (1974).
TLC2274M-MIL boyle_macromodel.gif Figure 53. Boyle Macromodel and Subcircuit

8.2 Typical Application

8.2.1 High-Side Current Monitor

TLC2274M-MIL app_sgls007.gif Figure 54. Equivalent Schematic (Each Amplifier)

8.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 3 as the input parameters.

Table 3. Design Parameters

PARAMETER VALUE
VBAT Battery voltage 12 V
RSENSE Sense resistor 0.1 Ω
ILOAD Load current 0 A to 10 A
Operational amplifier Set in differential configuration with gain = 10

8.2.1.2 Detailed Design Procedure

This circuit is designed for measuring the high-side current in automotive body control modules with a 12-V battery or similar applications. The operational amplifier is set as differential with an external resistor network.

8.2.1.2.1 Differential Amplifier Equations

Equation 1 and Equation 2 are used to calculate VOUT.

Equation 1. TLC2274M-MIL equation_01_sgls007.gif
Equation 2. TLC2274M-MIL equation_02_sgls007.gif

In an ideal case R1 = R and R2 = Rg, and VOUT can then be calculated using Equation 3:

Equation 3. TLC2274M-MIL equation_03_sgls007.gif

However, as the resistors have tolerances, they cannot be perfectly matched.

R1 = R ± ΔR1

R2 = R2 ± ΔR2

R = R ± ΔR

Rg = Rg ± ΔRg

Equation 4. TLC2274M-MIL equation_04_sgls007.gif

By developing the equations and neglecting the second order, the worst case is when the tolerances add up. This is shown by Equation 5.

Equation 5. TLC2274M-MIL equation_05_sgls007.gif

where

  • Tol = 0.01 for 1%
  • Tol = 0.001 for 0.1%

If the resistors are perfectly matched, then Tol = 0 and VOUT is calculated using Equation 6.

Equation 6. TLC2274M-MIL equation_06_sgls007.gif

The highest error is from the common mode, as shown in Equation 7.

Equation 7. TLC2274M-MIL equation_07_sgls007.gif

Gain of 10, Rg / R = 10, and Tol = 1%:

Common mode error = ((4 × 0.01) / 1.1) × 12 V = 0.436 V

Gain of 10 and Tol = 0.1%:

Common mode error = 43.6 mV

The resistors were chosen from 2% batches.

R1 and R 12 kΩ

R2 and Rg 120 kΩ

Ideal Gain = 120 / 12 = 10

The measured value of the resistors:

R1 = 11.835 kΩ

R = 11.85 kΩ

R2 = 117.92 kΩ

Rg = 118.07 kΩ

8.2.1.3 Application Curves

TLC2274M-MIL D001_SLOS190.gif Figure 55. Output Voltage Measured vs Ideal
(0 to 1 A)
TLC2274M-MIL D002_SLOS190.gif Figure 56. Output Voltage Measured vs Ideal
(0 to 10 A)