SLVSCH2 July   2014 TPS2105-EP

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1. 5.1 Function Table
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling 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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Power Switches
        1. 7.3.1.1 N-Channel MOSFET
        2. 7.3.1.2 P-Channel MOSFET
        3. 7.3.1.3 Charge Pump
        4. 7.3.1.4 Driver
        5. 7.3.1.5 Enable
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With EN Control
  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 Step-by-Step Design Procedure
        2. 8.2.2.2 Power-Supply Considerations
        3. 8.2.2.3 Switch Transition
        4. 8.2.2.4 Thermal Protection
        5. 8.2.2.5 Undervoltage Lockout
        6. 8.2.2.6 Power Dissipation and Junction Temperature
        7. 8.2.2.7 ESD Protection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  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

Package Options

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

7 Detailed Description

7.1 Overview

The TPS2105 is a dual-input, single-output power switch designed to provide uninterrupted output voltage when transitioning between two independent power supplies.

The device combines one N-channel (250-m) MOSFET with a single output. The P-channel MOSFET (IN2) is used with auxiliary power supplies that deliver lower current for standby modes. The N-channel MOSFET (IN1) is used with a main power supply that delivers higher current required for normal operation.

The low on-resistance makes the N-channel the ideal path for higher main supply current when power-supply regulation and system voltage drops are critical. When using the P-channel MOSFET, quiescent current is reduced to 0.75 µA to decrease the demand on the standby power supply.

The MOSFETs in the device do not have the parasitic diodes, typically found in discrete MOSFETs, thereby preventing back-flow current when the switch is off.

7.2 Functional Block Diagram

fbd_TPS2105_slvsch2.gif

7.3 Feature Description

7.3.1 Power Switches

7.3.1.1 N-Channel MOSFET

The IN1-OUT N-channel MOSFET power switch has a typical on-resistance of 250 mΩ at 5-V input voltage and is configured as a high-side switch.

7.3.1.2 P-Channel MOSFET

The IN2-OUT P-channel MOSFET power switch has a typical on-resistance of 1.3 Ω at 5-V input voltage and is configured as a high-side switch. When operating, the P-channel MOSFET quiescent current is reduced to typically 0.75 µA.

7.3.1.3 Charge Pump

An internal charge pump supplies power to the driver circuit and provides the necessary voltage to pull the gate of the MOSFET above the source. The charge pump operates from input voltages as low as 2.7 V and requires very little supply current.

7.3.1.4 Driver

The driver controls the gate voltage of the IN1-OUT and IN2-OUT power switches. To limit large current surges and reduce the associated electromagnetic interference (EMI) produced, the drivers incorporate circuitry that controls the rise times and fall times of the output voltage.

7.3.1.5 Enable

The logic enable turns on the IN2-OUT power switch when a logic low is present on EN. A logic high on EN restores bias to the drive and control circuits and turns on the IN1-OUT power switch. The enable input is compatible with both TTL and CMOS logic levels.

7.4 Device Functional Modes

7.4.1 Operation With EN Control

The logic enable turns on the IN1-OUT power switch when a logic high is present on EN. Also, a logic low present on EN turns off the IN1-OUT and turns on the IN2-OUT power switch.