New Generation Switching Power Manager with USB On-the-Go


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Introduction of the key features of the LTC3576, its basic operation and typical applications

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New Generation Switching Power Manager with USB On-the-Go

  1. 1. New Generation Switching Power Manager with USB On-the-Go <ul><li>Source: LINEAR TECHNOLOGY </li></ul>
  2. 2. Introduction <ul><li>Purpose </li></ul><ul><ul><li>This training module introduces the key features of the LTC3576, its basic operation and typical applications. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>Key features of the LTC3576 </li></ul></ul><ul><ul><li>Internal functional circuits </li></ul></ul><ul><ul><li>Typical applications </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>17 pages </li></ul></ul>
  3. 3. Design Challenges for USB-capable Charger <ul><li>USB-capable battery charging in many cases means more convenience to the user. </li></ul><ul><li>However, there are some limitations when the USB is used for charging the device’s batteries. </li></ul><ul><li>The main challenges for the system designer include: </li></ul><ul><ul><li>Maximizing current delivered from the USB port </li></ul></ul><ul><ul><li>Managing power flow between multiple input voltage sources, the battery and load </li></ul></ul><ul><ul><li>Minimizing heat </li></ul></ul><ul><ul><li>Maximizing charging efficiency </li></ul></ul><ul><ul><li>Minimizing solution footprint and profile </li></ul></ul>
  4. 4. A Solution for the Challenges - LTC3576 <ul><li>The LTC3576 is a member in a family of multifunction power management IC. It consists of: </li></ul><ul><ul><li>A bidirectional switching power manager with input overvoltage protection and USB On-The-Go (OTG) functionality </li></ul></ul><ul><ul><li>A stand-alone battery charger </li></ul></ul><ul><ul><li>Three high efficiency synchronous buck regulators </li></ul></ul><ul><ul><li>An ideal diode </li></ul></ul><ul><ul><li>I 2 C control </li></ul></ul><ul><ul><li>An always-on LDO </li></ul></ul><ul><li>The LTC3576 is available in a low profile 38-pin (4mm x 6mm x 0.75mm) QFN package. </li></ul><ul><li>The LTC3576 is designed to make optimal use of the power available from a variety of sources, while minimizing power dissipation and easing thermal budgeting constraints. </li></ul>
  5. 5. PowerPath Control <ul><li>Benefits: </li></ul><ul><ul><li>Bat-Track adaptive output control capability with an external high-voltage buck regulator </li></ul></ul><ul><ul><li>Improved thermal performance with power flowing to the system load </li></ul></ul><ul><ul><li>Improving power delivery efficiency to the system load and to the battery </li></ul></ul>USB Power in Power Out Step down regulator USB Current Limit Program & Monitor
  6. 6. USB On-the-Go (OTG) <ul><li>The bidirectional PowerPath switching regulator acts as a step-up converter to deliver power from V OUT to V BUS . </li></ul>
  7. 7. Input Current Limit Program <ul><li>The current limit value has 5 settings ranging from 500 µA to 1A. </li></ul><ul><li>The input current limit is programmed by </li></ul><ul><ul><li>I LIM0 & I LIM1 pins </li></ul></ul><ul><ul><li>I 2 C serial port </li></ul></ul>High Power Suspend (USB 2.5mA Limit) 0 1 1 X 0 X X D6 5x Mode (USB 100mA Limit) 1 1 Low Power Suspend (USB 500 µ A Limit) 0 1 10x Mode (Wall 1A Limit) 1 0 1x Mode (USB 100mA Limit) 0 0 USB Setting I LIM0 / C0 I LIM1 / C1
  8. 8. Bat-Track Control <ul><li>ACPR: indicates the external switching regulator is suitable for used by LT3576. </li></ul><ul><li>Wall: determine when power is applied to the external regulator. </li></ul><ul><li>V C : Bat-Track external switching regulator control output. </li></ul>When external power is detected, the USB input is automatically disabled.
  9. 9. Ideal Diode <ul><li>The ideal diode is always on and will respond quickly whenever V OUT drops below BAT. </li></ul><ul><li>The diode consists of a precision amplifier that controls the gate of an optional external ideal diode P-channel MOSFET. </li></ul>
  10. 10. Suspend LDO & Always-On LDO <ul><li>Suspend LDO </li></ul><ul><li>If the LTC3576 are configured for USB suspend mode, the bidirectional switching regulator is disabled and the suspend LDO provides power to the VOUT pin. </li></ul><ul><li>The suspend LDO will prevent the battery from running down when the portable product has access to a suspended USB port. </li></ul><ul><li>3.3V LDO Always-On LDO </li></ul><ul><li>This LDO is used to provide power to a system pushbutton controller, standby microcontroller or real time clock. </li></ul><ul><li>If the LDO3V3 output pin is not used, it should be disabled by connecting it to VOUT. </li></ul>
  11. 11. Battery Charge Control <ul><li>The constant-current/constant-voltage battery charger features: </li></ul><ul><ul><li>Automatic recharge </li></ul></ul><ul><ul><li>Automatic termination by safety timer </li></ul></ul><ul><ul><li>Low voltage trickle charging </li></ul></ul><ul><ul><li>Bad cell detection </li></ul></ul><ul><ul><li>Over-temperature charge pausing </li></ul></ul><ul><li>Depending on available input power and external load conditions, the battery charger may or may not be able to charge at the full programmed rate. </li></ul><ul><li>The CHRG pin indicates the status of the battery charger. </li></ul>
  12. 12. I 2 C Interface <ul><li>The LTC3576 may receive commands from a master device using 2-wire I 2 C interface. </li></ul><ul><li>The I 2 C port is designed to be operated at speeds of up to 400kHz. </li></ul><ul><li>The I 2 C serial port can be disabled by grounding the DVCC pin. </li></ul>Timing Diagram
  13. 13. General Purpose Step-down Regulators <ul><li>Three operating modes to meet the different noise / power needs. </li></ul><ul><ul><li>Pulse skip mode for moderate to heavy loads </li></ul></ul><ul><ul><li>Burst mode for light loads </li></ul></ul><ul><ul><li>LDO mode for light loads </li></ul></ul>
  14. 14. USB On-the-Go Application <ul><li>The LTC3576 as the host </li></ul><ul><li>The LTC3576 as the slave </li></ul>Fig 1 Fig 2
  15. 15. Typical Application 1
  16. 16. Typical Application 2 Same circuits to connect with the MCU, please refer to Application 1
  17. 17. Typical Application 3 Same circuits to connect with the MCU, please refer to Application 1
  18. 18. Additional Resource <ul><li>For ordering the LTC357 switching power manager, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For additional inquires contact our technical service hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li>,C1,C1003,C1037,C1773,P86476 </li></ul></ul>