SLUS525A March   2007  – September 2015 TPS61050 , TPS61052

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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 I2C Interface Timing Characteristics
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Efficiency
      2. 7.3.2 Soft-Start
      3. 7.3.3 Shutdown
      4. 7.3.4 LED Failure Modes
      5. 7.3.5 Undervoltage Lockout
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operating Modes: Torch and Flash
      2. 7.4.2 Mode of Operation: Flash Blanking (TPS61050)
      3. 7.4.3 Hardware Voltage Mode Selection (TPS61052)
      4. 7.4.4 Low Light Dimming Mode
    5. 7.5 Programming
      1. 7.5.1 3-Bit ADC
      2. 7.5.2 Serial Interface Description
      3. 7.5.3 F/S-Mode Protocol
      4. 7.5.4 TPS6105X I2C Update Sequence
    6. 7.6 Register Maps
      1. 7.6.1 Register Description
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application Schematic
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selecton
          2. 8.2.1.2.2 Capacitor Selection
            1. 8.2.1.2.2.1 Input Capacitor
            2. 8.2.1.2.2.2 Output Capacitor
          3. 8.2.1.2.3 Checking Loop Stability
        3. 8.2.1.3 Application Curves
      2. 8.2.2 High-Power White LED Solution Featuring Privacy Indicator
      3. 8.2.3 High-Power White LED Solution Featuring No-Latency Turn-Down Through PA TX Signal
      4. 8.2.4 High-Power White LED Flash Driver And AF/Zoom Motor Drive Supply
      5. 8.2.5 White LED Flash Driver and Audio Amplifier Power Supply Exclusive Operation
      6. 8.2.6 White LED Flash Driver and Audio Amplifier Power Supply Operating Simultaneously
      7. 8.2.7 White LED Flash Driver and Auxiliary Lighting Zone Power Supply
      8. 8.2.8 2 × 300 mA Dual LED Camera Flash
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Related Links
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Package Summary

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

The TPS6105x device is based on a high-frequency synchronous-boost topology with constant current sink to drive single white LEDs. The TPS6105x device not only operates as a regulated current source but also as a standard voltage-boost regulator. This additional operating mode can be useful to supply other high-power devices in the system, such as a hands-free audio power amplifier, or any other component requiring a supply voltage higher than the battery voltage.

8.2 Typical Applications

8.2.1 Typical Application Schematic

TPS61050 TPS61052 pmi_lus525.gif Figure 40. Typical Application Schematic

8.2.1.1 Design Requirements

This example illustrates how to use the TPS6105x to drive high power white LED. Table 3 shows the design parameters and example values.

Table 3. Design Parameters

DESIGN PARAMETERS EXAMPLE VALUES
Input voltage range 3.3 V to 4.2 V
Output voltage 5 V
Flash current 500 mA

8.2.1.2 Detailed Design Procedure

8.2.1.2.1 Inductor Selecton

A boost converter requires two main passive components for storing energy during the conversion. A boost inductor and a storage capacitor at the output are required. The TPS6105x device integrates a current limit protection circuitry. The peak current of the NMOS switch is sensed to limit the maximum current flowing through the switch and the inductor. The typical peak current limit (1000 mA / 1500 mA / 2000 mA) is user selectable through the I2C interface.

To optimize solution size the TPS6105x device has been designed to operate with inductance values from a minimum of 1.3 μH to a maximum of 2.9 μH. In typical high-current white LED applications, TI recommends an inductance of 2.2 μH.

To select the boost inductor, TI recommends keeping the possible peak inductor current below the current limit threshold of the power switch in the chosen configuration. The highest peak current through the inductor and the power switch depends on the output load, the input and output voltages. Estimation of the maximum average inductor current and the maximum inductor peak current can be done using Equation 1 and Equation 2:

Equation 1. TPS61050 TPS61052 eq1_il_lus525.gif
Equation 2. TPS61050 TPS61052 eq2_ilpeak_lus525.gif

with:

f = switching frequency (2 MHz)
L = inductance value (2.2 μH)
η = estimated efficiency (85%)

For example, for an output current of 500 mA at 5 V, the TPS6105x device must be set for a 1000 mA current limit operation together with an inductor supporting this peak current.

The losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for total circuit efficiency.

Table 4. List of Inductors

MANUFACTURER SERIES DIMENSIONS ILIM SETTINGS
TDK VLF3010AT 2.6 mm × 2.8 mm × 1 mm maximum height 1000 mA (typical)
TAIYO YUDEN NR3010 3 mm × 3 mm × 1 mm maximum height
TDK VLF3014AT 2.6 mm × 2.8 mm × 1.4 mm maximum height 1500 mA (typical)
COILCRAFT LPS3015 3 mm × 3 mm × 1.5 mm maximum height
MURATA LQH3NP 3 mm × 3 mm × 1.5 mm maximum height
TOKO FDSE0312 3 mm × 3 mm × 1.2 mm maximum height 2000 mA (typical)

8.2.1.2.2 Capacitor Selection

8.2.1.2.2.1 Input Capacitor

For good input voltage filtering low ESR ceramic capacitors are recommended. A 10-μF input capacitor is recommended to improve transient behavior of the regulator and EMI behavior of the total power supply circuit. The input capacitor should be placed as close as possible to the input pin of the converter.

8.2.1.2.2.2 Output Capacitor

The primary 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, by using Equation 3:

Equation 3. TPS61050 TPS61052 eq3_cmin_lus525.gif

Parameter f is the switching frequency and ΔV is the maximum allowed ripple.

With a chosen ripple voltage of 10mV, a minimum capacitance of 10 μF is needed. The total ripple is larger due to the ESR of the output capacitor. This additional component of the ripple can be calculated using Equation 4:

Equation 4. ΔVESR = IOUT × RESR

The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the capacitor. Additional ripple is caused by load transients. This means that the output capacitor must completely supply the load during the charging phase of the inductor. A reasonable value of the output capacitance depends on the speed of the load transients and the load current during the load change.

For the high current white LED application, a minimum of 3-μF effective output capacitance is usually required when operating with 2.2-μH (typical) inductors. For solution size reasons, this is usually one or more X5R/X7R ceramic capacitors. For stable operation of the internally compensated control loop, a maximum of 50 μF effective output capacitance is tolerable.

Depending on the material, size and margin to the rated voltage of the used output capacitor, degradation on the effective capacitance can be observed. This loss of capacitance is related to the DC bias voltage applied. It is therefore always recommended to check that the selected capacitors are showing enough effective capacitance under real operating conditions.

8.2.1.2.3 Checking Loop Stability

The first step of circuit and stability evaluation is to look from a steady-state perspective at the following signals:

  • Switching node, SW
  • Inductor current, IL
  • Output ripple voltage, VOUT(AC)

These are the basic signals that must be measured when evaluating a switching converter. When the switching waveform shows large duty cycle jitter or the output voltage or inductor current shows oscillations the regulation loop may be unstable. This is often a result of board layout and/or L-C combination.

The next step in regulation loop evaluation is to perform a load transient test. Output voltage settling time after the load transient event is a good estimate of the control loop bandwidth. The amount of overshoot and subsequent oscillations (ringing) indicates the stability of the control loop. Without any ringing, the loop has usually more than 45° of phase margin.

Because the damping factor of the circuitry is directly related to several resistive parameters (for example, MOSFET rDS(on)) that are temperature dependant, the loop stability analysis must be done over the input voltage range, output current range, and temperature range.

8.2.1.3 Application Curves

TPS61050 TPS61052 pwm_oper_lus525.gif Figure 41. PWM Operation
TPS61050 TPS61052 dwn_mode_lus525.gif Figure 42. Down-Mode Operation
TPS61050 TPS61052 v_trns_res_lus525.gif Figure 43. Voltage Mode Load Transient Response
TPS61050 TPS61052 duty_cyc_lus525.gif Figure 45. Duty Cycle Jitter
TPS61050 TPS61052 low_light_lus525.gif Figure 47. Low-Light Dimming Mode Operation
TPS61050 TPS61052 tx_msk_lus525.gif Figure 49. TX-Masking Operation
TPS61050 TPS61052 tx3_msk_lus525.gif Figure 51. TX-Masking Operation
TPS61050 TPS61052 startup_lus525.gif Figure 53. Start-Up in Torch Operation
TPS61050 TPS61052 dwn2_mode_lus525.gif Figure 44. Down-Mode Line Transient Response
TPS61050 TPS61052 in_ripp_lus525.gif Figure 46. Input Ripple Voltage
TPS61050 TPS61052 torch_fls_lus525.gif Figure 48. Torch/Flash Sequence
TPS61050 TPS61052 tx2_msk_lus525.gif Figure 50. TX-Masking Operation
TPS61050 TPS61052 tj_mont_lus525.gif Figure 52. Junction Temperature Monitoring
TPS61050 TPS61052 startup2_lus525.gif Figure 54. Start-Up in Torch Operation

8.2.2 High-Power White LED Solution Featuring Privacy Indicator

Figure 55 shows the typical application where TPS61050 is used to drive high-power white LED with a privacy indicator feature.

TPS61050 TPS61052 wht_led_pvt_lus525.gif Figure 55. High-Power White LED Solution Featuring Privacy Indicator

8.2.3 High-Power White LED Solution Featuring No-Latency Turn-Down Through PA TX Signal

Figure 56 shows the typical application where TPS61050 is used to drive high-power white LED, and the RF PA TX signal is used to realize the no-latency turn down function.

TPS61050 TPS61052 wht_led_tx_lus525.gif Figure 56. High-Power White LED Solution Featuring No-Latency Turn-Down Through PA TX Signal

8.2.4 High-Power White LED Flash Driver And AF/Zoom Motor Drive Supply

Figure 57 shows the typical application where TPS61052 is used as high-power white LED flash driver and meantime to provide the power supply to the AF/Zoom motor driver.

TPS61050 TPS61052 motor_drv_lus525.gif Figure 57. High-Power White LED Flash Driver And AF/Zoom Motor Drive Supply

8.2.5 White LED Flash Driver and Audio Amplifier Power Supply Exclusive Operation

Figure 58 shows the typical application where TPS61052 is used as white LED flash driver and it can also be used to provide the power supply to the audio amplifier exclusively by using a logic gate 1G97.

TPS61050 TPS61052 pwr_sup_lus525.gif Figure 58. White LED Flash Driver and Audio Amplifier Power Supply Exclusive Operation

8.2.6 White LED Flash Driver and Audio Amplifier Power Supply Operating Simultaneously

Figure 59 shows the typical application where TPS61052 is used as white LED flash driver and meantime to provide the power supply to the audio amplifier simultaneously.

TPS61050 TPS61052 flashlit_lus525.gif Figure 59. White LED Flash Driver and Audio Amplifier Power Supply Operating Simultaneously

8.2.7 White LED Flash Driver and Auxiliary Lighting Zone Power Supply

Figure 60 shows the typical application where TPS61052 is used as white LED flash driver and meantime to provide the supply to the auxiliary lighting zone (TCA6507 in this example).

TPS61050 TPS61052 zone_pwr_lus525.gif Figure 60. White LED Flash Driver and Auxiliary Lighting Zone Power Supply

8.2.8 2 × 300 mA Dual LED Camera Flash

Figure 61 shows the typical application where TPS61050 is used to drive dual LED camera flash (2 × 300 mA).

TPS61050 TPS61052 flash_led_lus525.gif Figure 61. 2 × 300 mA Dual LED Camera Flash