• Fully programmable LP3971 Power Management Unit
• Freescale MC9S08 8-bit microcontroller to manage the voltage setting and sequencing
• Visual Basic PC application to interact with the board and its settings

Design Description

The LP3971 Smart Power Board provides a complete, multi-rail solution for FPGAs, Microprocessors, or any other systems requiring multiple voltages, special power sequencing, and boot management. This solution utilizes the National Semiconductor LP3971 Power Management Unit and an 8 bit microcontroller to manage the features of the PMU. There are more then billion combinations of initial voltage values for the output voltages, this solution can provide them all regardless the chip hard-coded startup values.

An RS-232 port and Windows application are also provided to simplify evaluation of the solution using a PC; however, this is not required for a final system implementation.

LP3971 Key Specifications:

Three Buck Regulators

Programmable V _OUT from 0.8 to 3.3V
Up to 95% efficiency
Up to 1.6A output current

 Six Accurate LDOs
Programmable V_OUT of 1.0V-3.3V
±3% output voltage accuracy
150/300/370mA output currents
100mV (typ) dropout
      LDO 1 300 mA
      LDO 2 150mA
      LDO 3 150mA
      LDO 4 150mA
      LDO 5 370mA
      LDO RTC 30mA 

•	RD-139 Reference Design Document
•	Design Files (Schematic, Board Layout, Gerber, BOM, firmware and VB application)

Additional Resources

Board Photo

LP3971 Smart Power Board Key Features

• Utilizes the National Semiconductor LP3971 Power Management Unit and the low cost Freescale 8-bit microcontroller
• Solution provides user control over all default voltage startup values, boot control (reset lines, enable lines, etc), order and time sequencing of rails. Power down sequencing is also possible with modifications to the firmware.
• Utilizes LP3971 GPIOs and / or MCU GPIO for boot control.
  - Power-on Reset
  - Peripheral Reset
  - Control of reset polarity and drive type (“open drain” like, push-pull)
• Board also provides jumpers to allow insertion for current monitoring of loads or input.
• The control values stored in the MCU flash can be easily modified for FPGAs, DSPs, other processors, and any other multi-rail devices without changing the firmware which speeds time to market.

LP3971 Device Special Features

• Compatible with advanced applications processors requiring DVM (Dynamic Voltage Management)
• Three buck regulators for powering high current processor functions or I/O’s
• 6 LDO’s for powering RTC, peripherals, and I/O’s
• Backup battery charger with automatic switch for lithium manganese coin cell batteries and Super capacitors
• I ² C compatible high speed serial interface
• Software control of regulator functions and settings
• Precision internal reference
• Thermal overload protection
• Current overload protection
• Tiny 40-pin 5 x 5 mm LLP package
  

Designed for National by: