Portable Power Management

Market: Power (Handheld/Portable Electronics)
Target Platform: VCA-2
Application: Power Management +Plus
Figure 1 – Power management Application Space
Figure 1 – Power management Application Space

Portable Power Management Market

Handheld electronics such as PDAs, GPS receivers, games, and medical devices integrate a wide variety of logic, memory, and analog functions into a small battery powered unit. Efficiently providing power to all of the mixed signal components in such devices is a challenging proposition. A given product may have a wide number of voltage domains from 1.8V up to 40V. The core system processor may be a 1.8V or 3.3V device, the USB interface is running at 5V, LED and LED back lighting may require up to 40V supplies.

Power Sequencing

Power sequencing turns on the various voltage regulators in the correct order for power on, reset, sleep-modes, and power off states. Some voltages may require soft turn on where the voltage ramps to a requested voltage at a pre-programmed rate. This power sequencing requires digital timers and analog voltage sensing to control the sequencing and to detect over-voltage and fault conditions.

Regulator Topology Options

The power regulation topology options include linear regulators, switching regulators and low drop out (LDO) regulators. Buck regulators are used to reduce a high battery voltage down to 3.3V or 1.8V to power digital and low-voltage analog circuitry. Boost regulators are used to increase the battery voltage to provide higher voltages from 6V to 40V to such features as LED-based display
back lighting where a string of 10 LEDs can require voltages from 36 to 40V. A portable system can easily require 5 to 8 different regulators and the cost of the regulators and required support circuitry along with wasted PCB space can quickly add expense to a product.

Rechargeable Battery Management

Many portable systems contain rechargeable batteries and the power management solution has the responsibility of safely and quickly recharging the battery, monitoring of the battery’s capacity, and switching power from the battery to an external supply when connected to USB or an external transformer.

Power Management Building Blocks

Integrating the multiple power regulation components into a Triad Semiconductor via configurable array (VCA) saves on board area, component cost and manufacturing cost. Triad’s high voltage VCAs have an extensive set of mixed signal IP optimized for creating integrated power management controllers. The integrated controller saves cost and enables precise control of power sequencing, reset control, sleep-mode control, and brown-out sequencing. Triad’s power management building blocks include:

Analog Building Blocks
  • Linear Regulators
  • Switching Regulators
  • Low Drop Out (LDO) Regulators
  • Power On Reset Generator
  • Brown Out Detector
  • Lithium-Ion, Lithium-Polymer Battery Manager
  • Battery Charger
  • LED Boost Converter 3.3V to 50V output
  • LCD Backlighting Boost Regulator
  • Battery Fuel Gauge
  • Monitoring ADCs
  • Reference DACs
  • On-board Temperature Sensor
  • Remote Temperature Sensor Processing
  • General Sensor Input Processing
  • H-Bridge
  • General Filtering
  • Comparators
Digital Building Blocks
  • Power Sequencing State Machine
  • Embedded Processor for Power Management and General-Purpose Programming
  • Non-Volatile Memory for program storage, unique ID, voltage, timing,
    and
  • temperature settings and calibration data.
  • SPI or IIC “Smart-Power” Interface and Control from a remote
  • processor
  • SMBus™ Power Management Bus
Audio Processing
  • I2S Digital Audio Receiver
  • Digital & Analog Filtering
  • Audio Mixing
  • Audio DAC & Class D Amplifier
Human Interface
  • LCD Bias Generators
  • Capacitive Touch Sensor Controller
  • Touch Screen Controller

Power Management +Plus Triad VCA ASIC

Consider a typical portable application containing a microprocessor, back-lit LCD, audio, and capacitive button interfaces with the unit being powered by a lithium ion battery that is rechargeable via USB or an external power connection. This type of system has the following power management needs:

  • 4.2 to 3.3V Regulation
  • 4.2 to 3.3V Sleep-mode LDO Regulation
  • 4.2 to 1.8V Regulation
  • 5V to 4.2 Lithium-ion Battery Charging
  • Battery Fuel Gauge
  • Brown-Out Detector
  • 36V Boost Regulator for LED-based LCD back-lighting
  • Coordinated Power Sequencing for the individual Regulators

All of these functions can be integrated onto a Triad VCA. Triad’s high-voltage power management optimized VCA-2 platform is ideal for this type of application. The VCA-2 contains the following resources:

Digital Resources
  • 9,000 Logic Gates
  • 12 64×16 SRAM (12Kbits total SRAM)
  • 1Kx8 EEPROM

Supports multiple power regions from 2.6V to 50V

Analog Resources
  • 6 High Voltage General-Purpose Analog Tiles
    • Each Tile has 2 op-amps plus arrays of: Capacitors, Resistors,
      Switches, Transistors
  • 4 General-Purpose Analog Tiles
    • Each Tile has 2 op-amps plus arrays of: Capacitors, Resistors,
      Switches, Transistors
  • 1 High Voltage Reference Tile
    • Boost-strapping band-gap to regulate high voltage down to 3.3V
      to start the power sequencing of the array
  • 6 High Voltage Power Management Tiles
  • 1 Reference Tile containing: Band-gap, 2 op-amps, Transistor Array
    for supplying bias currents
  • 2 Wideband Amplifiers
  • 2 Low Noise Amplifiers
  • Analog to Digital Converter

Figure 2 - VCA-2 High Voltage Platform
Figure 2 – VCA-2 High Voltage Platform

The VCA-2 building blocks also enable the integration of non-power management features such as:

  • Touch Screen Controller
  • Capacitive Touch Button Interface
  • Audio I2S Receiver
  • Audio Class D Amplifier
  • Audio H-Bridge
  • General-Purpose Analog to Digital Converter

These functions can be combined into a single cost effect solution as shown in the ASIC block diagram in Figure 3.

Figure 3 – Power Management +Plus ASIC on Triad VCA-2
Figure 3 – Power Management +Plus ASIC on Triad VCA-2