SNVSCS6 March   2026 TPS7H1301-SP

ADVMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Options Table
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Quality Conformance Inspection
    7. 7.7 Typical Characteristics
  9. 8 Parameter Measurement Information
  10. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Enable
      2. 9.3.2  Charge Pump
        1. 9.3.2.1 Charge Pump Operation
        2. 9.3.2.2 Foldback Switching
      3. 9.3.3  Startup
      4. 9.3.4  Power Good
      5. 9.3.5  Output Voltage
      6. 9.3.6  Dropout
      7. 9.3.7  Output Voltage Accuracy
      8. 9.3.8  Output Noise
      9. 9.3.9  Power Supply Rejection Ratio
      10. 9.3.10 Stability
        1. 9.3.10.1 Stability of the TPS7H1301
        2. 9.3.10.2 Stability of the TPS7H1302
      11. 9.3.11 Thermal Shutdown
    4. 9.4 Device Functional Modes
      1. 9.4.1 Enable Disable
  11. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Capacitor Selection
          1. 10.2.2.1.1 Input Capacitor (CIN) Selection
          2. 10.2.2.1.2 CFLY
          3. 10.2.2.1.3 CPOUT Capacitor
          4. 10.2.2.1.4 Bypass Capacitors
          5. 10.2.2.1.5 Output Capacitor
        2. 10.2.2.2 Charge Pump Output Resistance
        3. 10.2.2.3 Output Noise
        4. 10.2.2.4 PSRR Design Implications
        5. 10.2.2.5 Stability Design Considerations
      3. 10.2.3 Application Curves
    3. 10.3 Power Supply Recommendations
    4. 10.4 Layout
      1. 10.4.1 Layout Guidelines
      2. 10.4.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information
    1.     69
10.2.2.1.2 CFLY

CFLY is the charge pump capacitor that transfers charge from the input to the charge pump output (CPOUT pin).

For typical high-current applications, TI recommends a nominally rated 1μF or two in parallel 0.680μF ceramic output capacitors for stable operation. Polarized capacitors (tantalum, aluminum, electrolytic, and so forth) must not be used for the flying capacitor, as polarized capacitors can become reverse-biased during operation.

If CFLY is sized too small, the charge pump is unable to support high current applications; conversely if CFLY is too large, the charge pump can overwhelm CIN and CCPOUT capacitors, resulting in increased input and output voltage ripple.

Dropout Current is reliant on the charge pump resistance and voltage droop, which is directly affected by the choice of CFLY; selecting a capacitor that is too small or too high ESR increases charge pump output resistance, such that the resulting voltage droop lowers the available headroom for the integrated LDO.

Consideration of CFLY capacitor characteristics, such as DC bias, temperature coefficient are essential in assessing the contribution of the capacitor to charge pump resistance; Equation 8 calculates the fly capacitors contribution to the overall charge pump output resistance and VDROOP. Note, that the min switching frequency (fSW) from the Electrical Characteristics table is the more conservative esitimation parameter; as min fSW results in a higher charge pump resistance..

Equation 8. RCFLY=1fSW×CCFLYmin+4×RESRCFLY

As Equation 8 shows, a typical reduction in output capacitance due to DC Bias and temperature typically reduces overall CFLY capacitance by 15% to 25% and thus increases charge pump output resistance.

To calculate CFLY(min) consult the capacitor manufacturer data and apply the overall tolerance, DC Bias, and temperature derating: For example, a 25V 1μF X7R capacitor with the following parameters:

  • Case Size: 0805
  • Tolerance: -5%
  • DC Bias @ 5V: -4.56%
  • Temperature derating @ 125ºC: -14.56%
  • RESR @ 400kHz: 10mΩ

Table 10-2 is an example tradeoff for selecting either a solitary 1μF (nom.) capacitor or two 0.68μF (nom) capacitors; the overall contribution of CFLY to the resistance of the charge pump is compared against component count (additional board area).

Table 10-2 CFLY Comparison
Attribute 1μF 2x 0.68μF
QTY 1 2 (parallel)
Case Size 0805 0805
Voltage Rating 25V 25V
Dielectric X7R X7R
Derating Parameters
Tolerance -5% -5%
DC Bias @ 5V -4.56% -2.6%
Tempco. @ 125ºC -14.56% -13.47%
Results
Effective Capacitance 0.775μF 1.073μF
ESR 10mΩ 6.9mΩ (effective res.)
RCFLY 3.45Ω 2.55Ω

To calculate the minimum capacitance for CFLY use :

Equation 9. C F L Y ( m i n ) =   C F L Y ( n o m ) × T o l . × D C   B i a s × T e m p

Applying Equation 9 for the 1μF (nom.) capacitor:

Equation 10. C F L Y ( m i n ) = 1 µ F × 1 - 0.05 × 1 - 0.0456 × 1 - 0.1456 = 0.775 µ F

The worst case contribution of CFLY is calculated by applying Equation 8 (1μF (nom.) example)

Equation 11. RCFLY= 1400kHz×0.775µF+4×10mΩ=3.45Ω

Table 10-2 shows that the additional component count of the two 0.68μF capacitors offers a significant reduction in the contribution of CFLY to overall charge pump output resistance. Applications at higher operating temperatures, operating currents, or lower VIN benefit from more from overall lower charge pump output resistance. This design examples uses a VIN of 5V and a ILOAD of 250mA is sufficiently served by the 1μF CFLY capacitor.