SLCS160 June   2017 LM139-MIL

 

  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 Electrical Characteristics
    6. 6.6 Switching Characteristics
    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
      1. 7.4.1 Voltage Comparison
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Voltage Range
        2. 8.2.2.2 Minimum Overdrive Voltage
        3. 8.2.2.3 Output and Drive Current
        4. 8.2.2.4 Response Time
      3. 8.2.3 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. Validate and test the design implementation to confirm system functionality.

8.1 Application Information

Typically, a comparator compares either a single signal to a reference, or to two different signals. Many users take advantage of the open-drain output to drive the comparison logic output to a logic voltage level to an MCU or logic device. The wide supply range and high voltage capability makes the LM139-MIL device optimal for level shifting to a higher or lower voltage.

8.2 Typical Application

LM139-MIL LM139-MIL_typ_app.gif Figure 7. Single-Ended and Differential Comparator Configurations

8.2.1 Design Requirements

For this design example, use the parameters listed in Table 1 as the input parameters.

Table 1. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input Voltage Range 0 V to Vsup-1.5 V
Supply Voltage 4.5 V to VCC maximum
Logic Supply Voltage 0 V to VCC maximum
Output Current (RPULLUP) 1 µA to 4 mA
Input Overdrive Voltage 100 mV
Reference Voltage 2.5 V
Load Capacitance (CL) 15 pF

8.2.2 Detailed Design Procedure

When using the LM139-MIL in a general comparator application, determine the following:

  • Input voltage range
  • Minimum overdrive voltage
  • Output and drive current
  • Response time

8.2.2.1 Input Voltage Range

When choosing the input voltage range, the input common-mode voltage range (VICR) must be taken in to account. If temperature operation is above or below 25°C the VICR can range from 0 V to VCC– 2 V. This limits the input voltage range to as high as VCC– 2 V and as low as 0 V. Operation outside of this range can yield incorrect comparisons.

The following list describes the outcomes of some input voltage situations.

  • When both IN– and IN+ are both within the common-mode range:
    • If IN– is higher than IN+ and the offset voltage, the output is low and the output transistor is sinking current
    • If IN– is lower than IN+ and the offset voltage, the output is high impedance and the output transistor is not conducting
  • When IN– is higher than common mode and IN+ is within common mode, the output is low and the output transistor is sinking current
  • When IN+ is higher than common mode and IN– is within common mode, the output is high impedance and the output transistor is not conducting
  • When IN– and IN+ are both higher than common mode, the output is low and the output transistor is sinking current

8.2.2.2 Minimum Overdrive Voltage

Overdrive voltage is the differential voltage produced between the positive and negative inputs of the comparator over the offset voltage (VIO). To make an accurate comparison, the overdrive voltage (VOD) must be higher than the input offset voltage (VIO). Overdrive voltage can also determine the response time of the comparator, with the response time decreasing with increasing overdrive. Figure 8 and Figure 9 show positive and negative response times with respect to overdrive voltage.

8.2.2.3 Output and Drive Current

Output current is determined by the load and pullup resistance and logic and pullup voltage. The output current produces a low-level output voltage (VOL) from the comparator, where VOL is proportional to the output current.

The output current can also effect the transient response.

8.2.2.4 Response Time

Response time is a function of input over-drive. See the Typical Characteristics graphs for typical response times. The rise and fall times can be determined by the load capacitance (CL), load/pull-up resistance (RPULLUP) and equivalent collector-emitter resistance (RCE).

  • The rise time (τR) is approximately τR~ RPULLUP × CL
  • The fall time (τF) is approximately τF ~ RCE × CL
    • RCE can be determined by taking the slope of Figure 3 in its linear region at the desired temperature, or by dividing the VOL by IOUT

8.2.3 Application Curves

Figure 8 and Figure 9 were generated with scope probe parasitic capacitance of 50 pF.

LM139-MIL LM139-MIL_C004.png
VCC = 5 V VLogic = 5 V RPULLUP = 5.1 kΩ
Figure 8. Response Time vs Output Voltage
(Positive Transition)
LM139-MIL LM139-MIL_C006.png
VCC = 5 V VLogic = 5 V RPULLUP = 5.1 kΩ
Figure 9. Response Time vs Output Voltage
(Negative Transition)