SNVSAO4D December   2017  – August 2020 LMZM33602

PRODUCTION DATA  

  1. 1Features
  2. 2Applications
  3. 3Description
  4. 4Revision History
  5. 5Pin Configuration and Functions
    1.     Pin Functions
  6. 6Specifications
    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. 7Detailed 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  Feedforward Capacitor, CFF
      3. 7.3.3  Voltage Dropout
      4. 7.3.4  Switching Frequency (RT)
      5. 7.3.5  Synchronization (SYNC)
      6. 7.3.6  Input Capacitors
      7. 7.3.7  Output Capacitors
      8. 7.3.8  Output On/Off Enable (EN)
      9. 7.3.9  Programmable Undervoltage Lockout (UVLO)
      10. 7.3.10 Power Good (PGOOD)
      11. 7.3.11 Overcurrent Protection (OCP)
      12. 7.3.12 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Shutdown Mode
  8. 8Application 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 Feedforward 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. 9Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary

7.3.1 Adjusting the Output Voltage

A resistor divider connected to the FB pin (pin 16) programs the output voltage of the LMZM33602. The output voltage adjustment range is from 1 V to 18 V. Figure 7-1 shows the feedback resistor connections for setting the output voltage. The recommended value of RFBB is 10 kΩ. The value for RFBT can be calculated using Equation 1. Depending on the output voltage, a feedforward capacitor, CFF, can be required for optimum transient performance. Table 7-1 lists the standard external RFBT and CFF values for several output voltages between 2.5 V and 18 V. Table 7-2 lists the values for output voltages below 2.5 V. Additionally, Table 7-1 and Table 7-2 include the recommended switching frequency (FSW), the frequency setting resistor (RRT), and the minimum and maximum output capacitance for each of the output voltages listed.

For designs with RFBB other than 10 kΩ, adjust CFF and RFBT such that (CFF × RFBT) is unchanged and adjust RFBT such that (RFBT / RFBB) is unchanged.

Equation 1. GUID-D5C60D6C-9662-4827-AF50-9A6693AC105C-low.gif
GUID-3CD78330-03D9-4F10-AB66-3D80BACCF109-low.gifFigure 7-1 Setting the Output Voltage
Table 7-1 Required Component Values (VOUT ≥ 2.5 V)
VOUT (V)RFBT (kΩ)(3)CFF (pF)fSW (kHz)RRT (kΩ)COUT(min) (µF)(1)COUT(max) (µF)(2)
2.515.0220250162150400
3.323.215030013388300
540.210045088.766200
649.96855071.554160
7.564.94765060.440130
980.64770056.236110
12110open90044.22280
13.5124open100039.22275
15140open110035.72065
18169open120033.21655
(1) For output voltages ≥ 2.5 V, the minimum required output capactiance must be comprised of ceramic type and account for DC bias and temperature derating.
(2) The maximum output capactiance must include the required ceramic COUT(min). Additional capacitance, may be ceramic type, low-ESR polymer type, or a combination of the two.
(3) RFBB = 10.0 kΩ
Table 7-2 Required Component Values (VOUT < 2.5 V)
VOUT (V)RFBT (kΩ)(1)CFF (pF)FSW (kHz)RRT (kΩ)COUT
1 to 2.5See Equation 1open250162150-µF ceramic +
470-µF polymer
(1) RFBB = 10 kΩ. For VOUT = 1 V, RFBB= open and RFBT = 0 Ω.