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  • TPS51120 Dual, Synchronous Step-Down Controller With 100-mA Standby Regulators for Notebook System Power

    • SLUS670C JULY   2005  – January 2015 TPS51120

      PRODUCTION DATA.  

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  • TPS51120 Dual, Synchronous Step-Down Controller With 100-mA Standby Regulators for Notebook System Power
  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 Recommended Operating Conditions
    3. 6.3 Thermal Information
    4. 6.4 Electrical Characteristics
    5. 6.5 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  PWM Operation
      2. 7.3.2  Adaptive On-Time Control
      3. 7.3.3  Light Load Operation
      4. 7.3.4  Forced PWM Operation
      5. 7.3.5  5-V, 100-mA, LDO and Switchover (VREG5)
      6. 7.3.6  3.3-V, 100-mA, LDO and Switchover (VREG3)
      7. 7.3.7  2-V, 50-uA Sink - Source Reference (VREF2)
      8. 7.3.8  Low-Side Driver
      9. 7.3.9  High-Side Driver
      10. 7.3.10 Soft-Start
      11. 7.3.11 Soft-Stop
      12. 7.3.12 Powergood
      13. 7.3.13 Current Sensing and Overcurrent Protection
      14. 7.3.14 Overvoltage Protection
      15. 7.3.15 Undervoltage Protection
      16. 7.3.16 5-V Supply and UVLO Protection
      17. 7.3.17 VIN Line Sag Protection (Dynamic UVP)
      18. 7.3.18 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Current Mode
        1. 7.4.1.1 Current Mode Operation
      2. 7.4.2 D-Cap Mode
        1. 7.4.2.1 D-Cap Mode Operation
    5. 7.5 Programming
  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
      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 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
  13. IMPORTANT NOTICE
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DATA SHEET

TPS51120 Dual, Synchronous Step-Down Controller With 100-mA Standby Regulators for Notebook System Power

1 Features

  • 3.3-V and 5-V 100-mA Bootstrapped Standby Regulators with Independent Enables
  • Selectable D-CAP™ Mode Enables Fast Transient Response Less than 100 ns
  • Selectable Low Ripple Current Mode
  • Less than 1% Internal Reference Accuracy
  • Selectable PWM-only/Auto-skip Modes
  • Low-side RDS(on) Loss-less Current Sensing
  • RSENSE Accurate Current Sense Option
  • Internal Soft-Start and Integrated VOUT Discharge Transistors
  • Integrated 2-V Reference
  • Adaptive Gate Drivers with Integrated Boost Diode
  • Powergood for Each Channel with Delay Timer
  • Fault Disable Mode
  • Supply Input Voltage Range: 4.5 V to 28 V

2 Applications

    Notebook Computers System Bus and I/O

3 Description

The TPS51120 is a highly sophisticated dual, synchronous step-down controller. It is a full featured controller designed to run directly off a three- or four-cell Li-ion battery and provide high-power and 5-V and/or 3.3-V standby regulation for all the downstream circuitry in a notebook computer system. High-current, 100-mA, 5-V or 3.3-V on-board linear regulators have glitch-free switch over function to SMPS and can be kept alive independently during standby state. The pseudo-constant frequency adaptive on-time control scheme supports full range of current mode operation including simplified loop compensation, ceramic output capacitors as well as seamless transition to reduced frequency operation at light-load condition. Optional D-CAP mode operation optimized for SP-CAP or POSCAP output capacitors allows further reduction of external compensation parts. Dynamic UVP supports VIN line sag without latch off by hitting 5-V UVP. No negative voltage appears at output voltage node during UVLO, UVP, and OCP, OTP or loss of VIN.

The TPS51120 32-pin QFN package is specified from –40°C to 85°C ambient temperature.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
TPS51120 VQFN (32) 5.00 mm × 5.00 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Reference Design for D-CAP Mode Converter

v05074_lus670.gif

4 Revision History

Changes from B Revision (Feburary 2007) to C Revision

  • Added Pin Configuration and Functions section, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go

5 Pin Configuration and Functions

RHB Package
32-Pin VQFN
Bottom View
po_lus670.gif

Pin Functions

PIN I/O DESCRIPTION
NAME NO.
COMP1 2 O Loop compensation pin (error amplifier output). Connect RC from this pin to GND for proper loop compensation with current mode operation. Tie this pin to V5FILT for D-CAP mode operation.
COMP2 7 O
CS1 23 I Current sense comparator input (-) for resistor sensing scheme. Or, overcurrent trip setting input for RDS(on) current sense scheme if connected to V5FILT through the threshold setting resistor.
CS2 18 I
DRVH1 27 O High-side MOSFET gate drive output. Source 3.5 Ω, sink 1.5 Ω, LL-node referenced floating driver. Drive voltage corresponds to VBST to LL voltage.
DRVH2 14 O
DRVL1 25 O Rectifying (low-side) MOSFET gate drive output. Source 3.5 Ω, sink 1.5 Ω, PGND referenced driver. Drive voltage is VREG5 voltage.
DRVL2 16 O
EN1 29 I Channel 1 and Channel 2 SMPS enable pins. Connect to 5 V to turn on with internal 3-ms soft-start. Slower soft-start is possible by applying an external capacitor from each of these pins to ground to program ramp rate.
EN2 12 I
EN3 10 I VREG3, 3.3-V low dropout linear regulator enable pin. Connect to GND to disable. Float or tie to enabled VREG5 to turn on the regulator.
EN5 9 I VREG5, 5-V low dropout linear regulator enable pin. Connect to GND to disable. Float or tie to VBAT to turn on the regulator.
GND 5 I Signal ground pin.
LL1 26 I/O High-side MOSFET gate driver return. Also serve as current sense comparator input (-) for RDS(on) sensing, and input voltage monitor for on-time control circuitry
LL2 15 I/O
PGND1 24 I/O Ground return for rectifying MOSFET gate driver. Connect PGND2, PGND1 and GND strongly together near the source of the rectifying FET or the GND connection of the current sense resistor. Also serve as current sense comparator input (+).
PGND2 17 I/O
PGOOD1 30 O Power-good window comparator open drain output. Pull up with resistor to V5FILT or appropriate signal voltage. Current capability is 5-mA. PGOOD goes high 1-ms after VFB is within specified limits. Power bad (terminal goes low) is within 10 μs.
PGOOD2 11 O
SKIPSEL 32 I Skip and fault mode selection pin. Refer to Table 5
TONSEL 31 I On-time selection pin. Refer to Table 1 and Table 5.
V5FILT 20 I 5-V supply input for the entire control circuit. Should be provided from VREG5 via RC filter.
VBST1 28 I Supply Input for High-side MOSFET Driver. Connect capacitor from this pin to respective LL terminal. An internal PN diode is connected between VREG5 to each of these pins. User can add external schottky diode if forward drop is critical to drive the power MOSFET.
VBST2 13 I
VFB1 3 I SMPS feedback input. Connect the feedback resistor divider here for adjustable outputs. Tie these pins to V5FILT or for fixed output option. Refer to Table 5
VFB2 6 I
VIN 22 I Supply Input for 5-V and 3.3-V linear regulator. Typically connected to VBAT.
VO1 1 I These terminals serve four functions: on-time adjustment, output discharge, VREG5, VREG3 switchover input and feedback inputs for 5-V, 3.3-V fixed-output option. Connect to positive terminal of respective switch mode power supply’s output capacitor.
VO2 8 I
VREF2 4 O 2-V reference output. Capable of ±50-μA, ±2% over 0 - 85°C temperature range. Bypass to GND by 1-nF ceramic capacitor. Tie this pin to GND disables both SMPS.
VREG3 19 O 3.3-V, 100-mA low dropout linear regulator output. Bypass to PGND by 10-μF ceramic capacitor. Runs from VIN supply. Shuts off with EN3. Switches over to VO2 when 3.1 V or above is provided.
VREG5 21 O 5-V, 100-mA low dropout linear regulator output. Bypass to PGND by 10-μF ceramic capacitor. Runs from VIN supply. Internally connected to VBST and DRVL. Shuts off with EN5. Switches over to VO1 when 4.8 V or above is provided.

 
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