# Presentation: 213591

## Implementing Low Power Mode in Set Top Boxes

- STB International Stakeholder Meeting
- San Francisco, California
- Suzanne Foster
- Ecos Consulting
- 970.259.6801 x 302
- sfoster@ecosconsulting.com

## Possible Design Changes to Make Low Power Mode Possible

- Hardware enabling shut down of non critical systems
- Hardware build so that circuits not in use can be powered down and then “wake” easily and quickly when needed for service
- Analogous to “sleep” technology developed by Intel and others in PC world, sold in virtually all PCs on shelves today
- Memory solutions already found in desktops could store program guide, etc. when in low power mode
- Hardware reducing power use, regardless of mode** **
- “Power partitioning” chips
- Power supply

**Notes:**
Hardware that reduces power use in all modes will help with the 15W standby active level proposed by australia

AMD’s Cool and Quiet technology and Intel’s Demand Based Switching technology are two examples of proven strategies that could be translated to the STB platform; Other power partitioning technologies are available from Sun, Apple, and Transmeta.

## Power Partitioning Chips Save Energy in Desktops

*	**     **stock power supply*

- Power Partitioning Chips Save Energy in Desktops

**Notes:**
Between 15 and 20 percent savings in desktop computers when computer is asked to perform few computations

## Power Supply Possible Near Term Solution

- Power Supply Possible Near Term Solution

- Efficiencies between 68% and 82% measured, 85% efficiency achievable today

**Notes:**
 Costs computer manufacturer about $0.04 to $0.05 per watt Costs computer manufacturer about $0.04 to $0.05 per
in volume in volume – about $12 to $25 each about $12 to $25 each
operate it over its lifetime User pays about $100 to $150 to operate it over its lifetime

In the post regulator and the main converter, most energy savings to be had

 Lower circuit stresses Lower circuit
•
Temperature Temperature
•
Voltage Voltage
•
Current Current
    Improved reliability Improved reliability
    Reduced fan noise Reduced fan noise
    Reduced energy waste at electrical outlet and in Reduced energy waste at electrical outlet and in
building distribution wiring (lower I building distribution wiring (lower I2R losses) R losses)
    Operating cost savings large enough to pay back Operating cost savings large enough to pay back
less extra manufacturing costs in a year or less
 Add active PFC Add active
    Reduces voltage and current stress at line extremes Reduces voltage and current stress at line extremes
    Reduces EMI filtering Reduces EMI filtering
    Improves reliability of a good design Improves reliability of a good design
    Cost impact: ~ $1.50 @ 400W Cost impact: ~ $1.50 @ 400W
    Add active clamp to main converter Add active clamp to main converter
    Improves efficiency and increases parts integration Improves efficiency and increases parts integration
    Optimizes design to adjust for regulated input voltage Optimizes design to adjust for regulated input voltage
    Cost impact: ~ $0.75 @ 400W Cost impact: ~ $0.75 @ 400W
    Improve output regulators Improve output regulators
    Add synchronous regulators Add synchronous regulators
    Replace rectifiers with switches and add control IC Replace rectifiers with switches and add control IC
    Improves efficiency, especially at partial load Improves efficiency, especially at partial load
400W Cost Impact: ~ $0.75 @ 400W

In the near term, while hardware solutions, software solutions, and alternative communication protocols that allow lower power modes are being developed, power supply efficiency can be a way to reduce overall power use regardless of mode of operation or software employed.  Improving power supply efficiency reduces the energy use of STBs and the energy savings are readily available and automatic. In all of the boxes surveyed for this project, the STB power supply was located on a board separate from the rest of the circuitry and the two boards were connected with some type of wire connector. This suggests that the design and circuitry layout associated with the functionality of the STB does not have to be altered in order to introduce a more efficient power supply into future STB designs 

## Possible Design Changes to Make Low Power Mode Possible (cont.)

- Software changes to accommodate low power mode
- “Energy Saver” DVR options that allow hard drives to spin down if customer chooses not to record material
- Communication protocols
- enable proper security and downloads of content to customer from head end
- communication among multiple STBs in one home

## Goal: Energy Savings in Customer’s Homes

- Possible for low power mode to be technically achievable and measurable in the lab, but not implemented in the field
- Reasons for this could include:
- Needs of the service provider not fully taken into account when designing system, so low power mode is disabled in field
- Customer dissatisfaction with solution
- Lack of transparency to user
- Customer misunderstands important environmental impact and associated energy bill savings
- Poor communication protocols between head end and box and among boxes

**Notes:**
Equivalent of taking 3 larger power plants (500 MW) out of commission

## Test Method Implications

- IEC 62087 currently measures static power values for defined modes
- Alternate approach: measurement of STB energy over 24 hour period with standard duty cycle, allowing box to fall into low power as it would in the home
- Other considerations:
- Easy to conduct
- Reproducible
- Robust
- Representative

## Discussion