SLVS821E May   2008  – May 2019 TPS61087

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Soft-Start
      2. 7.3.2 Frequency Select Pin (FREQ)
      3. 7.3.3 Undervoltage Lockout (UVLO)
      4. 7.3.4 Thermal Shutdown
      5. 7.3.5 Overvoltage Prevention
    4. 7.4 Device Functional Modes
  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 Inductor Selection
        2. 8.2.2.2 Rectifier Diode Selection
        3. 8.2.2.3 Setting the Output Voltage
        4. 8.2.2.4 Compensation (COMP)
        5. 8.2.2.5 Input Capacitor Selection
        6. 8.2.2.6 Output Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 General Boost Application Circuits
      2. 8.3.2 TFT LCD Application
      3. 8.3.3 White LED Applications
  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 Third-Party Products Disclaimer
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2.4 Compensation (COMP)

The regulator loop can be compensated by adjusting the external components connected to the COMP pin. The COMP pin is the output of the internal transconductance error amplifier.

Standard values of RCOMP = 16 kΩ and CCOMP = 2.7 nF will work for the majority of the applications.

See Table 5 for dedicated compensation networks giving an improved load transient response. The following equations can be used to calculate RCOMP and CCOMP:

Equation 9. TPS61087 q3_1_lvs821.gif

with

VIN Minimum input voltage
VS Output voltage
Cout Output capacitance
L Inductor value, for example, 3.3 μH or 6.8 μH
Iout Maximum output current in the application

Make sure that RCOMP < 120 kΩ and CCOMP> 820 pF, independent of the results of the above formulas.

Table 5. Recommended Compensation Network Values at High/Low Frequency

FREQUENCY L VS VIN ± 20% RCOMP CCOMP
High (1.2 MHz) 3.3 μH 15 V 5 V 100 kΩ 820 pF
3.3 V 91 kΩ 1.2 nF
12 V 5 V 68 kΩ 820 pF
3.3 V 68 kΩ 1.2 nF
9 V 5 V 39 kΩ 820 pF
3.3 V 39 kΩ 1.2 nF
Low (650 kHz) 6.8 μH 15 V 5 V 51 kΩ 1.5 nF
3.3 V 47 kΩ 2.7 nF
12 V 5 V 33 kΩ 1.5 nF
3.3 V 33 kΩ 2.7 nF
9 V 5 V 18 kΩ 1.5 nF
3.3 V 18 kΩ 2.7 nF

Table 5 gives conservative RCOMP and CCOMP values for certain inductors, input and output voltages providing a very stable system. For a faster response time, a higher RCOMP value can be used to enlarge the bandwidth, as well as a slightly lower value of CCOMP to keep enough phase margin. These adjustments should be performed in parallel with the load transient response monitoring of TPS61087.