SLVS279D March   2000  – August 2015 TPS61000 , TPS61002 , TPS61005 , TPS61006 , TPS61007

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Available Options
  6. Pin Configuration and Functions
  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 Typical Characteristics
  8. Parameter Measurement Information
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagrams
    3. 9.3 Feature Description
      1. 9.3.1 Controller Circuit
      2. 9.3.2 Device Enable
      3. 9.3.3 Undervoltage Lockout
      4. 9.3.4 Low-Battery Detector Circuit (LBI and LBO)
      5. 9.3.5 Low-EMI Switch
      6. 9.3.6 Adjustable Output Voltage (TPS61000 and TPS61007 Only)
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power Save Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Schematic of TPS6100x Evaluation Modules (TPS6100XEVM156)
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Programming the TPS61000 and TPS61007 Adjustable Output Voltage Devices
        2. 10.2.2.2 Programming the Low Battery Comparator Threshold Voltage
        3. 10.2.2.3 Inductor Selection
        4. 10.2.2.4 Capacitor Selection
        5. 10.2.2.5 Rectifier Selection
        6. 10.2.2.6 Compensation of the Control Loop
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
    2. 13.2 Related Links
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • DGS|10
散热焊盘机械数据 (封装 | 引脚)

10 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.

10.1 Application Information

The TPS6100x boost converter family is intended for systems that are powered by a single-cell NiCd or NiMH battery with a typical terminal voltage between 0.9 V to 1.6 V. It can also be used in systems that are powered by two-cell NiCd or NiMH batteries with a typical stack voltage between 1.8 V and 3.2 V. Additionally, singleor dual-cell, primary and secondary alkaline battery cells can be the power source in systems where the TPS6100x is used.

10.1.1 Schematic of TPS6100x Evaluation Modules (TPS6100XEVM156)

TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 ai_sch_lvs279.gifFigure 16. Schematic of TPS6100x Evaluation Modules

Evaluation modules are available for device types TPS61000, TPS61002, TPS61003, and TPS61006.

10.2 Typical Application

TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 ai_adj_cir_lvs279.gifFigure 17. Typical Application Circuit for Adjustable Output Voltage Option

10.2.1 Design Requirements

See Table 2 for design parameters.

Table 2. TPS6100x Output Design Parameters

DESIGN PARAMETERS VALUES
Input voltage range 1.8 V to 3.3 V
Output voltage 3.3 V
Output voltage ripple ±3% VOUT

10.2.2 Detailed Design Procedure

10.2.2.1 Programming the TPS61000 and TPS61007 Adjustable Output Voltage Devices

The output voltage of the TPS61000 and TPS61007 can be adjusted with an external resistor divider. The typical value of the voltage on the FB pin is 500 mV in fixed-frequency operation and 485 mV in the power-save operation mode. The maximum allowed value for the output voltage is 3.3 V. The current through the resistive divider should be about 100 times greater than the current into the FB pin. The typical current into the FB pin is 0.01 µA, and the voltage across R4 is typically 500 mV. Based on those two values, the recommended value for R4 is in the range of 500 kΩ in order to set the divider current at 1 µA. From that, the value of resistor R3, depending on the needed output voltage VOUT, can be calculated using the following equation:

Equation 1. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q1_r3r4_lvs279.gif

If, as an example, an output voltage of 2.5 V is needed, a 2-MΩ resistor should be chosen for R3.

The TPS61007 is an improved version of the TPS61000 adjustable output voltage device. The FBGND pin is internally connected to GND.

10.2.2.2 Programming the Low Battery Comparator Threshold Voltage

The current through the resistive divider should be about 100 times greater than the current into the LBI pin. The typical current into the LBI pin is 0.01 µA. The voltage across R2 is equal to the reference voltage that is generated on-chip, which has a value of 500 mV ±15 mV. The recommended value for R2 is therefore in the range of 500 kΩ. From that, the value of resistor R1, depending on the desired minimum battery voltage (VBAT), can be calculated using the following equation:

Equation 2. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q2_r1r2_lvs279.gif

For example, if the low-battery detection circuit should flag an error condition on the LBO output pin at a battery voltage of 1 V, a resistor in the range of 500 kΩ should be chosen for R1.

The output of the low battery comparator is a simple open-drain output that goes active low if the battery voltage drops below the programmed threshold voltage on LBI. The output requires a pullup resistor with a recommended value of 1MΩ, and should only be pulled up to the VOUT. If not used, the LBO pin can be left floating.

10.2.2.3 Inductor Selection

The output filter of inductive switching regulators is a low pass filter of second order. It consists of an inductor and a capacitor, often referred to as storage inductor and output capacitor.

To select an inductor, keep the possible peak inductor current below the current limit threshold of the power switch in your chosen configuration. For example, the current limit threshold of the TPS61006’s switch is 1100 mA at an output voltage of 3.3 V. The highest peak current through the inductor and the switch depends on the output load, the input (VBAT), and the output voltage (VOUT). Estimation of the maximum average inductor current can be done using the following equation:

Equation 3. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q3_il_lvs279.gif

For example, for an output current of 100 mA at 3.3 V, at least 515-mA current flows through the inductor at a minimum input voltage of 0.8 V.

The second parameter for choosing the inductor is the desired current ripple in the inductor. Normally it is advisable to work with a ripple of less than 20% of the average inductor current. A smaller ripple reduces the magnetic hysteresis losses in the inductor as well as output voltage ripple and EMI. But in the same way, the regulation time at load change rises. In addition, a larger inductor increases the total system cost.

With those parameters it is possible to calculate the value for the inductor:

Equation 4. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q4_l_lvs279.gif

where

  • f is the switching frequency
  • ΔIL is the ripple current in the inductor, that is 20% x IL

In this example, the desired inductor has the value of 12 µH. With this calculated value and the calculated currents, it is possible to chose a suitable inductor. Care has to be taken that load transients and losses in the circuit can lead to higher currents as estimated in equation 3. Also, the losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for total circuit efficiency.

The following inductors from different suppliers were tested. All work with the TPS6100x converter within their specified parameters:

Table 3. Recommended Inductors

VENDOR PART NUMBER
Coilcraft DO1608P Series
DS1608P Series
DO3308 Series
Coiltronics UP1B Series
UP2B Series
Murata LQH3N Series
Sumida CD43 Series
CD54 Series
CDR74B Series
TDK NLC453232T Series

10.2.2.4 Capacitor Selection

The major parameter necessary to define the output capacitor is the maximum allowed output voltage ripple of the converter. This ripple is determined by two parameters of the capacitor, the capacitance and the ESR. It is possible to calculate the minimum capacitance needed for the defined ripple, supposing that the ESR is zero.

Equation 5. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q5_cmin_lvs279.gif

where

  • f is the switching frequency
  • ΔV is the maximum allowed ripple.

With a chosen ripple voltage of 15 mV, a minimum capacitance of 10 µF is needed. The total ripple will be larger due to the ESR of the output capacitor. This additional component of the ripple can be calculated using the following equation:

Equation 6. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q6_deltav_lvs279.gif

An additional ripple of 30 mV is the result of using a tantalum capacitor with a low ESR of 300 mΩ. The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the capacitor. In this example, the total ripple is 45 mV. It is possible to improve the design by enlarging the capacitor or using smaller capacitors in parallel to reduce the ESR or by using better capacitors with lower ESR, like ceramics. For example, a 10-µF ceramic capacitor with an ESR of 50 mΩ is used on the evaluation module (EVM). Tradeoffs have to be made between performance and costs of the converter circuit.

A 10-µF input capacitor is recommended to improve transient behavior of the regulator. A ceramic capacitor or a tantalum capacitor with a 100-nF ceramic capacitor in parallel placed close to the IC is recommended.

10.2.2.5 Rectifier Selection

The rectifier diode has a major impact on the overall converter efficiency. Standard diodes are not suitable for low-voltage switched mode power supplies. A Schottky diode with low forward voltage and fast reverse recovery should be used as a rectifier to minimize overall losses of the dc-dc converter. The maximum current rating of the diode must be high enough for the application. The maximum diode current is equal to the maximum current in the inductor that was calculated in equation 3. The maximum reverse voltage is the output voltage. The chosen diode should therefore have a reverse voltage rating higher than the output voltage.

Table 4. Recommended Diodes

VENDOR PART NUMBER
Motorola Surface Mount MBRM120LT3
MBR0520LT1
Motorola Axial Lead 1N1517
RB520S-30
ROHM RB160L–40

The typical forward voltage of those diodes is in the range of 0.35 to 0.45 V assuming a peak diode current of 600 mA.

10.2.2.6 Compensation of the Control Loop

An R/C/C network must be connected to the COMP pin in order to stabilize the control loop of the converter. Both the pole generated by the inductor L1 and the zero caused by the ESR and capacitance of the output capacitor must be compensated. The network shown in Figure 18 satisfies these requirements.

TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 ai_loop_ctl_lvs279.gifFigure 18. Compensation of the Control Loop

Resistor RC and capacitor CC2 depend on the chosen inductance. For a 33-µH inductor, the capacitance of CC2 should be chosen to 33 nF, or in other words, if the inductor is xx µH, the chosen compensation capacitor should be xx nF, the same number value. The value of the compensation resistor is then chosen based on the requirement to have a time constant of 0.3 ms for the R/C network of RC and CC2; hence for a 33-nF capacitor, a 10-kΩ resistor should be chosen for RC.

Capacitor CC1 is depending on the ESR and capacitance value of the output capacitor, and on the value chosen for RC. Its value is calculated using following equation:

Equation 7. TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 q7_cc1_lvs279.gif

For a selected output capacitor of 22 µF with an ESR of 0.2 Ω, and RC of 33 kΩ, the value of CC1 is in the range of 100 pF.

Table 5. Recommended Compensation Components

INDUCTOR
[µH]
OUTPUT CAPACITOR RC
[kΩ]
CC1
[pF]
CC2
[nF]
CAPACITANCE
[µF]
ESR
[Ω]
33 22 0.2 10 100 33
22 22 0.3 15 100 22
10 22 0.4 33 100 10
10 10 0.1 33 100 10

10.2.3 Application Curves

TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 tc_vo_t_lvs279.gifFigure 19. TPS61006 Output Voltage Ripple Amplitude
TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 tc_io_t_lvs279.gifFigure 21. TPS61006 Load Transient Response
TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 tc_vo_io_t_lvs279.gifFigure 23. TPS61006 Start-up Timing Into 33-Ω Load
TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 tc_vsw_t_lvs279.gifFigure 20. TPS61006 Output Voltage Ripple Amplitude
TPS61000 TPS61001 TPS61002 TPS61003 TPS61004 TPS61005 TPS61006 TPS61007 tc_io2_t_lvs279.gifFigure 22. TPS61006 Line Transient Response