SNVS697E January   2011  – December 2016 SM72485

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 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 Control Circuit Overview
      2. 7.3.2 Current Limit
      3. 7.3.3 N-Channel Buck Switch and Driver
      4. 7.3.4 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Start-Up Regulator (VCC)
      2. 7.4.2 Regulation Comparator
      3. 7.4.3 Overvoltage Comparator
      4. 7.4.4 ON-Time Generator and Shutdown
  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 Selection of External Components
          1. 8.2.2.1.1  RFB1 and RFB2
          2. 8.2.2.1.2  Fs and RT
          3. 8.2.2.1.3  L1
          4. 8.2.2.1.4  C3
          5. 8.2.2.1.5  C2 and R3
          6. 8.2.2.1.6  ESR and R3
          7. 8.2.2.1.7  RCL
          8. 8.2.2.1.8  D1
          9. 8.2.2.1.9  C1
          10. 8.2.2.1.10 C4
          11. 8.2.2.1.11 C5
        2. 8.2.2.2 Low Output Ripple Configurations
          1. 8.2.2.2.1 Reduced Ripple Configuration
          2. 8.2.2.2.2 Minimum Ripple Configuration
          3. 8.2.2.2.3 Alternate Minimum Ripple Configuration
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

5 Pin Configuration and Functions

DGK Package
8-Pin VSSOP
Top View
SM72485 30142303.gif
NGU Package
8-Pin WSON
Top View
SM72485 30142302.gif

Pin Functions

PIN TYPE(1) DESCRIPTION
NAME VSSOP WSON
BST 2 2 I An external capacitor is required between the BST and the SW pins. TI recommends a 0.01-µF ceramic capacitor. An internal diode charges the capacitor from VCC during each off-time.
FB 5 5 I This pin is connected to the inverting input of the internal regulation comparator. The regulation threshold is 2.5 V.
RCL 3 3 I A resistor between this pin and RTN sets the off-time when current limit is detected. The off-time is preset to 35 µs if FB = 0 V.
RT/SD 6 6 I A resistor between this pin and VIN sets the switch on-time as a function of VIN. The minimum recommended on-time is 400 ns at the maximum input voltage. This pin can be used for remote shutdown.
RTN 4 4 G Ground for the entire circuit.
SW 1 1 O Power switching node. Connect to the output inductor, re-circulating diode, and bootstrap capacitor.
VCC 7 7 I This regulated voltage provides gate drive power for the internal Buck switch. An internal diode is provided between this pin and the BST pin. A local 0.47-µF decoupling capacitor is required. The series pass regulator is current limited to 9 mA.
VIN 8 8 I Input operating voltage: 6 V to 95 V.
Exposed Pad — Thermal Pad NC The exposed pad has no electrical contact. Connect to system ground plane for reduced thermal resistance.
(1) G = Ground, I = Input, O = Output, NC = No Contact