SNVSAO6C September   2017  – March 2018 LMZM33603

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Simplified Schematic
  3. 3 Description
    1.     Safe Operating Area
  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 Switching Characteristics
    7. 6.7 Typical Characteristics (VIN = 5 V)
    8. 6.8 Typical Characteristics (VIN = 12 V)
    9. 6.9 Typical Characteristics (VIN = 24 V)
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Adjusting the Output Voltage
      2. 7.3.2  Feed-Forward Capacitor, CFF
      3. 7.3.3  Output Current vs Output Voltage
      4. 7.3.4  Voltage Dropout
      5. 7.3.5  Switching Frequency (RT)
      6. 7.3.6  Synchronization (SYNC)
      7. 7.3.7  Input Capacitors
      8. 7.3.8  Output Capacitors
      9. 7.3.9  Output On/Off Enable (EN)
      10. 7.3.10 Programmable Undervoltage Lockout (UVLO)
      11. 7.3.11 Power Good (PGOOD)
      12. 7.3.12 Overcurrent Protection (OCP)
      13. 7.3.13 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Shutdown Mode
  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 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Output Voltage Setpoint
        3. 8.2.2.3 Feed-Forward Capacitor (CFF)
        4. 8.2.2.4 Setting the Switching Frequency
        5. 8.2.2.5 Input Capacitors
        6. 8.2.2.6 Output Capacitor Selection
        7. 8.2.2.7 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 Theta JA vs PCB Area
    4. 10.4 EMI
      1. 10.4.1 EMI Plots
    5. 10.5 Package Specifications
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Custom Design With WEBENCH® Tools
    2. 11.2 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

7.3.5 Switching Frequency (RT)

The switching frequency range of the LMZM33603 is 200 kHz to 1.2 MHz. The switching frequency can easily be set by connecting a resistor (RRT) between the RT pin and AGND. Additionally, the RT pin can be left floating and the LMZM33603 will operate at 400 kHz default switching frequency. Use Equation 3 to calculate the RRT value for a desired frequency or simply select from Table 3 or Table 4.

The switching frequency must be selected based on the output voltage setting of the device. See Table 3 for RRT resistor values and the allowable output voltage range for a given switching frequency for three common input voltages. Additionally, if an application requires 2 A or less of output current, use Table 4 to determine the allowable output voltage range for a given switching frequency

Equation 3. LMZM33603 Rrt.gif

Table 3. Switching Frequency vs Output Voltage (IOUT = 3 A)

SWITCHING FREQUENCY (kHz) RRT RESISTOR (kΩ) VIN = 5 V (±5%) VIN = 12 V (±5%) VIN = 24 V (±5%)
VOUT RANGE (V) VOUT RANGE (V) VOUT RANGE (V)
MIN MAX MIN MAX MIN MAX
200 200 1 3 1 5.1 1 3.8
250 158 1 3.2 1 5.8 1 5.2
300 133 1 3.2 1 6.4 1 7.1
350 113 1 3.1 1 6.9 1 10.2
400 100 or
(RT pin open)		 1 3.1 1 7.5 1 10.9
450 88.7 1 3.1 1 7.9 1.2 11.5
500 78.7 1 3 1 8.4 1.3 12.2
550 71.5 1 3 1 8.8 1.4 12.8
600 66.5 1 3 1 9 1.6 13.4
650 60.4 1 2.9 1 8.9 1.7 13.5
700 56.2 1 2.9 1 8.9 1.8 13.5
750 52.3 1 2.9 1 8.8 2.0 13.5
800 49.9 1 2.8 1 8.7 2.1 13.5
850 46.4 1 2.8 1.1 8.6 2.2 13.5
900 44.2 1 2.8 1.2 8.5 2.3 13.5
950 41.2 1 2.7 1.2 8.4 2.5 13.5
1000 39.2 1 2.7 1.3 8.4 2.6 13.5
1050 37.4 1 2.7 1.4 8.3 2.7 13.5
1100 35.7 1 2.6 1.4 8.2 2.9 13.5
1150 34 1 2.6 1.5 8.1 3 13.5
1200 33.2 1 2.6 1.6 8 3.1 13.5

Table 4. Switching Frequency vs Output Voltage (IOUT ≤ 2A)

SWITCHING FREQUENCY (kHz) RRT RESISTOR (kΩ) VIN = 5 V (±5%) VIN = 12 V (±5%) VIN = 24 V (±5%)
VOUT RANGE (V) VOUT RANGE (V) VOUT RANGE (V)
MIN MAX MIN MAX MIN MAX
200 200 1 3.4 1 5.5 1 6.2
250 158 1 3.5 1 6.2 1 10.6
300 133 1 3.5 1 6.8 1 10.6
350 113 1 3.5 1 7.4 1 10.7
400 100 or
(RT pin open)		 1 3.5 1 7.9 1 11.4
450 88.7 1 3.5 1 8.4 1.2 12.1
500 78.7 1 3.5 1 8.9 1.3 12.8
550 71.5 1 3.4 1 9.3 1.4 13.4
600 66.5 1 3.4 1 9.5 1.6 14.1
650 60.4 1 3.4 1 9.4 1.7 14.6
700 56.2 1 3.3 1 9.3 1.8 15.2
750 52.3 1 3.3 1 9.2 2 15.8
800 49.9 1 3.3 1 9.1 2.1 16.3
850 46.4 1 3.2 1.1 9.0 2.2 16.8
900 44.2 1 3.2 1.2 9.0 2.3 17.3
950 41.2 1 3.2 1.2 8.9 2.5 17.8
1000 39.2 1 3.1 1.3 8.8 2.6 18
1050 37.4 1 3.1 1.4 8.7 2.7 18
1100 35.7 1 3.1 1.4 8.6 2.9 18
1150 34 1 3 1.5 8.5 3 18
1200 33.2 1 3 1.6 8.5 3.1 18