SLOS190H February   1997  – March 2016 TLC2272 , TLC2272A , TLC2272AM , TLC2272M , TLC2274 , TLC2274A , TLC2274AM , TLC2274M

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 TLC2272 and TLC2272A Electrical Characteristics VDD = 5 V
    6. 6.6 TLC2272 and TLC2272A Electrical Characteristics VDD± = ±5 V
    7. 6.7 TLC2274 and TLC2274A Electrical Characteristics VDD = 5 V
    8. 6.8 TLC2274 and TLC2274A Electrical Characteristics VDD± = ±5 V
    9. 6.9 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 Related Links
    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 (1) and subcircuit in Figure 59 were generated using the TLC227x 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).
TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM boyle_macromodel.gif Figure 59. Boyle Macromodel and Subcircuit

8.2 Typical Application

8.2.1 High-Side Current Monitor

TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM app_sgls007.gif Figure 60. 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 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. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM equation_01_sgls007.gif
Equation 2. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM equation_02_sgls007.gif

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

Equation 3. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM 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. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM 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. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM 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. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM equation_06_sgls007.gif

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

Equation 7. TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM 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

TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM D001_SLOS190.gif Figure 61. Output Voltage Measured vs Ideal
(0 to 1 A)
TLC2272 TLC2272A TLC2272M TLC2272AM TLC2274 TLC2274A TLC2274M TLC2274AM D002_SLOS190.gif Figure 62. Output Voltage Measured vs Ideal
(0 to 10 A)