SNVS793D November   2011  – May 2015 LM3269

PRODUCTION DATA.  

  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 System Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 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 Dynamically Adjustable Output Voltage
      2. 7.3.2 Seamless Buck Transition
      3. 7.3.3 Thermal Overload Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable And Shutdown Mode
      2. 7.4.2 VCON,ON
      3. 7.4.3 Pulse Frequency Modulation (PFM) Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Setting The Output Voltage
      2. 8.1.2 Output Current Capacity
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Recommended External Components
          1. 8.2.2.1.1 Inductor Selection
          2. 8.2.2.1.2 Input Capacitor Selection
          3. 8.2.2.1.3 Output Capacitor Selection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Overview
        1. 10.1.1.1 PCB
          1. 10.1.1.1.1 Energy Efficiency
          2. 10.1.1.1.2 EMI
        2. 10.1.1.2 Manufacturing Considerations
        3. 10.1.1.3 LM3269 RF Evaluation Board
        4. 10.1.1.4 Component Placement
        5. 10.1.1.5 PCB Considerations By Layer
          1. 10.1.1.5.1 VBATT
    2. 10.2 Layout Examples
    3. 10.3 DSBGA Package Assembly And Use
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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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

8.1.1 Setting The Output Voltage

The LM3269 features a pin-controlled variable output voltage which eliminates the need for external feedback resistors. It can be programmed for an output voltage from 0.6 V to 4.2 V by setting the voltage on the VCON pin, as in Equation 1.

Equation 1. VOUT = 3 × VCON

When VCON is between 0.2 V and 1.4 V, the output voltage will follow the formula in Equation 1.

8.1.2 Output Current Capacity

The LM3269 load capability is as shown in Table 1.

Table 1. Output Voltage vs. Maximum Output Current Derating

VOUT VBATT MAXIMUM IOUT CAPABILITY
4.2 V > 3 V 650 mA
2.7 V to 3 V 500 mA
3.8 V > 3 V 750 mA
2.7 V to 3 V 600 mA
< 1.5 V 2.7 V to 5.5 V 120 mA (in PFM mode)

8.2 Typical Application

LM3269 30173201.gif

8.2.1 Design Requirements

DESIGN PARAMETER EXAMPLE VALUE
Minimum input voltage 2.7 V
Minimum output voltage 0.6 V
Output current 0 to 750 mA
Switching frequency 2.4 MHz (typical)

8.2.2 Detailed Design Procedure

8.2.2.1 Recommended External Components

8.2.2.1.1 Inductor Selection

A 2.2-μH inductor with a saturation current rating over 1500 mA and low inductance drop at the full DC bias condition is recommended for almost all applications. An inductor with a smaller DC resistance, such as 110 mΩ (depending on case size of resistor), should be used for good efficiency.

Table 2. Suggested 2.2-µH Inductors

VENDOR MODEL DIMENSIONS (mm) ISAT
(30% drop)		 IRATING
(Δ40°)		 DCR
FDK MIPSZ2520D2R2 2.5 x 2.0 x 1.0 1.5 A 1.1 A 110 mΩ
Murata LQH2HPN1R0NG0 2.5 x 2.0 x 1.2 2 A 1.2 A 112 mΩ
Samsung CIG22H2R2MNE 2.5 x 2.0 x 1.2 1.9 A 1.6 A 116 mΩ
TDK TFM201610A2R2M 2.0 x 1.6 x 1.0 1.7 A 1.3 A 180 mΩ
TOKO DFE201612C2R2N 2.0 x 1.6 x 1.2 2.1 A 1.3 A 155 mΩ

8.2.2.1.2 Input Capacitor Selection

A ceramic input capacitor of 10 µF, 6.3 V, 0603 (1608) is recommended for use in most applications. Place the input capacitor as close as possible to the PVIN pin and PGND pin of the device. A larger value of higher voltage rating may be used to improve input filtering. Use X7R, X5R, or B types; do not use Y5V or F. DC board characteristics of ceramic capacitors must be considered when selecting case sizes like 0402 (1005). The input filter capacitor supplies current to the PFET (high-side) switch in first half of each cycle and reduces voltage ripple imposed on the input power source. A ceramic capacitor’s low equivalent series resistance (ESR) provides the best noise filtering of the input voltage spikes due to this rapidly changing current.

8.2.2.1.3 Output Capacitor Selection

Use a 4.7 µF capacitor for the output capacitor. Use of capacitor types such as X5R, X7R are recommended for the filter. These provide an optimal balance between small size, cost, reliability, and performance for cell phones and similar applications. Table 3 lists suggested part numbers and suppliers. DC bias characteristics of the capacitors must be considered while selecting the voltage rating and case size of the capacitor. Smaller case sizes for the output capacitor mitigate piezo-electric vibrations of the capacitor when the output voltage is stepped up and down at fast rates. However, they have a bigger percentage drop in value with DC bias. A 0603 (1608) case size capacitor is recommended for output. For RF Power Amplifier applications, split the output capacitor between DC-DC converter and RF Power Amplifier(s). (4.7 μF (0402 (1005)) + PA input cap (0402(1005)/0201(0603)) is recommended.) The optimum capacitance split is application dependent. Place all the output capacitors very close to their respective device.

NOTE

If using a 4.7 µF, 0402 (1005) as the output capacitor, the total recommended actual capacitance on VOUT bus should be at least 7 µF (4.7 µF + PA decoupling caps) to take into account the 0402 (1005) DC bias degradation and other tolerances.

Table 3. Suggested Capacitors

MODEL VENDOR
10 µF for CIN
C1608X5R0J106K (0603) TDK
CL05A106MQ5NUN (0402) Samsung
4.7 µF for COUT
C1608X5R0J475M (0603) TDK
CL05A475MQ5NRN (0402) Samsung
C1005X5RR0J475M (0402) TDK

8.2.3 Application Curves

LM3269 30173218.png
PVIN = 3.7 V VOUT = 0.8 V↔ 2 V RLOAD = 20 Ω
Figure 9. VOUT Transient Response (PFM ↔ PWM)
LM3269 30173213.png
PVIN = 3.37 V VOUT = 3.45 V Load = 500 mA
Figure 11. Boost Mode Operation
LM3269 30173211.png
PVIN= 3.7 V VOUT = 3.2 V Load = 500 mA
Figure 10. Buck Mode Operation
LM3269 30173217.png
PVIN = 3.8 V VOUT = 3.6 V IOUT = 600 mA
Figure 12. Buck-Boost Operation
LM3269 30173214.png
PVIN = 3.6 V VOUT = 3.45 V Load = 350 mA
Figure 13. Start-Up
LM3269 30173215.png
PVIN = 3.8 V VOUT = 3.45 V
Figure 15. Load Transient DC-DC
LM3269 30173212.png
PVIN Step = 3.6 V ↔ 4.2 V VOUT = 3 V Load = 320 mA
Figure 14. Line Transient For DC-DC