SLVSCQ8A December   2015  – April 2016 TPS54A20

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 Timing Requirements
    7. 6.7 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  Frequency Selection
      2. 7.3.2  External Clock Syncronization
      3. 7.3.3  Adjusting the Output Voltage
      4. 7.3.4  Soft Start
      5. 7.3.5  Startup into Pre-biased Outputs
      6. 7.3.6  Power Good (PGOOD)
      7. 7.3.7  Overcurrent Protection
      8. 7.3.8  Light Load Operation
      9. 7.3.9  Output Undervoltage/Overvoltage Protection
      10. 7.3.10 Input Undervoltage/Overvoltage Lockout
      11. 7.3.11 Enable and Adjusting Undervoltage Lockout
      12. 7.3.12 Series Capacitor Monitoring
        1. 7.3.12.1 Dropping Below 35% Threshold
        2. 7.3.12.2 Rising Above 65% Threshold
      13. 7.3.13 Thermal Shutdown
      14. 7.3.14 Phase A Power Stage
      15. 7.3.15 Phase B Power Stage
      16. 7.3.16 Internal Gate Drive Regulator
      17. 7.3.17 Voltage Feed Forward
      18. 7.3.18 Internal Oscillator
      19. 7.3.19 Pulse Frequency Detector
      20. 7.3.20 On-Time Generator
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Two-Phase Series Capacitor Buck Converter Topology
      2. 8.1.2 Converter Switch Configurations
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Output Voltage
        2. 8.2.2.2  Switching Frequency
        3. 8.2.2.3  On-Time
        4. 8.2.2.4  Inductor Selection
        5. 8.2.2.5  Output Capacitor Selection
        6. 8.2.2.6  Input Capacitor Selection
        7. 8.2.2.7  Series Capacitor Selection
        8. 8.2.2.8  Soft-Start Time Selection
        9. 8.2.2.9  Bootstrap Capacitor Selection
        10. 8.2.2.10 Gate Drive Capacitor Selection
        11. 8.2.2.11 Under Voltage Lockout Set Point
        12. 8.2.2.12 Current Limit Selection
      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
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RNJ|20
Thermal pad, mechanical data (Package|Pins)
Orderable Information

5 Pin Configuration and Functions

RNJ Package
VQFN (20 Pin)
Top View
TPS54A20 PackageTopView2.gif

Pin Functions

PIN I/O(1) DESCRIPTION
NAME NO.
AGND 1 G Analog signal ground of the IC. AGND should be connected to PGND and VG- at a single point on PCB (e.g. underneath the IC).
BOOTA 8 S Bootstrap capacitor node for phase A high-side MOSFET gate driver. Connect the bootstrap capacitor from this pin to the SCAP pin (pin 9).
BOOTB 10 S Bootstrap capacitor node for phase B high-side MOSFET gate driver. Connect the bootstrap capacitor from this pin to the SWB pin.
EN 4 I Enable pin. Floating this pin will enable the IC. Pull below 1.23V to enter shutdown mode. Can also be used to adjust the input undervoltage lockout above 8 V with two resistors.
FB 18 I Feedback pin for voltage regulation. Connect this pin to the center tap of a resistor divider to set the output voltage.
ILIM 5 I Current limit programming pin. A resistor between this pin and ground sets the current limit. If no resistor is included, the default load current limit is 15 A.
NC 11 No connect. This pin is not electrically connected to the IC and is included for board level reliability (BLR) purposes. Connect this pin to the SCAP trace.
PGND 2 G Power ground of the IC. PGND should be connected to AGND and VG- at a single point on PCB (e.g. underneath the IC). Thermal vias to internal ground planes should be added beneath this pin.
PGOOD 15 O Power good indicator. This pin is an open-drain output and will assert low if the output voltage is greater than ±5% away from the desired value or due to thermal shutdown, over-voltage/under-voltage, EN shutdown, or during soft start. A pull-up resistor can be connected between PGOOD and VG+ or an external logic supply pin.
SCAP 9,20 O Series capacitor pin. Connect a ceramic capacitor from pin 20 to the SWA pin.
SS/FSEL 6 I Soft start/frequency select pin. Connect a resistor from this pin to ground to set the soft-start time and the switching frequency. If no resistor is provided, the default setting of 4MHz oscillator frequency and 512µs soft start time is used.
SWA 13 O Switching node for phase A. Connect an inductor from this pin to the output capacitors.
SWB 12 O Switching node for phase B. Connect an inductor from this pin to the output capacitors.
SYNC 14 I External clock synchronization pin. An external clock signal can be connected to this pin to synchronize the oscillator frequency (within ±10% of the nominal frequency set via SS/FSEL).
TON 19 I On-time selection. An external resistor from this pin to the AGND pin programs the nominal on-time of the high side switches.
VG+ 16 S Gate driver positive supply pin. Connect a bypass capacitor from this pin to VG-. To improve converter efficiency, the internal regulator can be overridden by connecting an external 5V supply to this pin. This supply rail also provides power to the control circuitry.
VG- 17 G Gate driver supply return pin. VG- should be connected to PGND and AGND at a single point on PCB (e.g. underneath the IC).
VGA 7 S High side phase A gate driver supply pin. Connect a bypass capacitor from this pin to ground.
VIN 3 I The power input pin to the IC. Connect VIN to a supply voltage between 8 V and 14 V.
(1) I = Input, O = Output, S = Supply, G = Ground Return