There are many challenges when designing power systems for handheld and wearable devices. In each succeeding generation, power systems are becoming more complex, and yet the overall board area devoted to power components keeps getting smaller. To overcome these challenges, Silego has developed the concept of FPIs. Using FPIs, designers can divide their complex power system into some number of local power regions (or islands), each of which includes the power control, power sequencing and power regulation needed to support loads in the immediate vicinity. We believe this technique results in higher performance and a more efficient solution that can be flexibly tailored to the requirements of each individual system.

Benefits of GreenPAK with LDOs

• High Integration
  • Includes many components typically found in power systems
    • Power Control
    • Power Sequencing
    • Power Monitoring
    • Power Regulation
• Small Size
  • 2.0 x 3.0 STQFN packaging for small board area
• Tri-Mode 150 mA LDO Regulators:
  • Mode 0: 150mA output with Quiescent Current at ~60 μA
  • Mode 1: 100μA output with Quiescent Current at ~6 μA
  • Bypass Mode: Acts like a load switch
• Flexibility of GreenPAK Configurable Macro-cells
  • Analog Comparators
  • Combination Function Macro-cells
  • Asynchronous State Machine (ASM)
  • I²C Slave Protocol Interface

Using Asynchronous State Machine for Power Sequencing

The Asynchronous State Machine (ASM) macro-cell is perfect for driving a flexible power-sequencing architecture. The Graphic User Interface (GUI) based development tools allow the user to quickly define the operating states, the allowed transitions between states, and link to the signals that drive each state transition. Using other GreenPAK macro-cells allows the user to easily time based state transitions (using delay macro-cells) and logic functions (using Look-Up Tables). The example state machine shown below is the one used in the demo project to drive both the power sequencing signals for six power rails, as well as the signals to turn on the four LDOs in sequence.

Controlling LDOs with GreenPAK Resources

The LDOs included in these devices allow the user to control many aspects of the output dynamically during operation:

• Controlling Output Voltage: Each LDO can support two output voltages, which are user-selectable. There is an internal signal coming from the Connection Matrix that can switch the output voltage during operation.
• Controlling Power Consumption: Each LDO regulator can operate in MODE0 (standard active mode supporting full 150 mA output), as well as MODE1 (low power mode with maximum 100μ output with reduced quiescent current consumption.
• Load Switch Mode: Each LDO has a user-selectable option where regulator ceases to regulate and the power MOSFET is turned on as a power switch, passing the voltage applied to VIN directly to VOUT.
• Changing LDO Behavior Via I²C: All of the control features listed above can also be changed via I²C commands.