Transcript Low Power Design - Renesas e

Low Power Design
Renesas Electronics America Inc.
© 2012 Renesas Electronics America Inc. All rights reserved.
Renesas Technology & Solution Portfolio
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© 2012 Renesas Electronics America Inc. All rights reserved.
Microcontroller and Microprocessor Line-up
2010
2012
1200 DMIPS, Superscalar
 Automotive & Industrial, 65nm
 600µA/MHz, 1.5µA standby
1200 DMIPS, Performance
 Automotive, 40nm
 500µA/MHz, 35µA deep standby
32-bit
500 DMIPS, Low Power
 Automotive & Industrial, 90nm
 600µA/MHz, 1.5µA standby
165 DMIPS, FPU, DSC
 Industrial, 40nm
 200µA/MHz, 0.3µA deep standby
165 DMIPS, FPU, DSC
 Industrial, 90nm
 200µA/MHz, 1.6µA deep standby
8/16-bit
25 DMIPS, Low Power
 Industrial & Automotive, 150nm
 190µA/MHz, 0.3µA standby
10 DMIPS, Capacitive Touch
 Industrial & Automotive, 130nm
Wide
Format1µA
LCDs
 350µA/MHz,
standby
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© 2012 Renesas Electronics America Inc. All rights reserved.
Embedded Security, ASSP
 Industrial, 90nm
 1mA/MHz, 100µA standby
44 DMIPS, True Low Power
 Industrial & Automotive, 130nm
 144µA/MHz, 0.2µA standby
‘Enabling The Smart Society’
 ‘Portable and eventually wearable electronics will be a
hallmark of the Smart Society and powerful, energy efficient
MCUs are a key component of this future’
 Challenge:
“The kind of electronics that would be pervasive in a Smart
Society demand both powerful and highly energy efficient
MCUs; unlike the low-current low-performance MCUs used in
the past”
 Solution:
“This class will show you how to determine the important
MCU parameters and model the application to determine the
best power vs performance tradeoff in choosing an MCU.”
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© 2012 Renesas Electronics America Inc. All rights reserved.
Agenda
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Introduction
Choosing an MCU for a low power application
Lab outline
Run lab section 1-2
Discussion
Run lab section 3
Summary
© 2012 Renesas Electronics America Inc. All rights reserved.
Choosing an MCU for a Low Power Application
RL78
Performance
(CPU core)
Operating
voltage
Power
consumption
6
50MHz/78DMIPS
32MHz/40.6DMIPS
20MHz/[email protected]
4MHz/[email protected]
1.56DMIPS/MHz
1.27DMIPS/MHz
1.62 to 5.5V
0.2mA/MHz
4uA in Sleep
© 2012 Renesas Electronics America Inc. All rights reserved.
1.6 to 5.5V
0.07mA/MHz
0.6uA in Sleep
Choosing an MCU for a Low Power Application
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Identify peripherals required in low power mode
Determine low power numbers from data sheet
Determine transition time and current draw
Model the application for current draw
Calculate battery lifetime for given battery capacity
Parameter
Wake Up
Current (RL78)
Time
3 mA
7
0.6uA
5uS (32 MHz)
Current (RX200)
Time
Low Power Mode
18 mA
150uS (50 MHz)
© 2012 Renesas Electronics America Inc. All rights reserved.
4uA
Lab Outline
MCU
Codec
SPI data
SPI
FFT
IIC
LCD data
LCD
Sleep
SPI
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FFT
I2C
Codec sends out data over SPI at periodic intervals
MCU performs 128 point FFT on data
Results are displayed on an LCD with a fixed refresh rate
Return to low power mode until next cycle
© 2012 Renesas Electronics America Inc. All rights reserved.
Lab Outline
 SPI
 Takes 6.4 ms to acquire 128 samples at 20KHz sample rate
128/20000 = 6.4ms
 Assume Codec has no buffer; thus MCU has to be reading each
sample as generated
 FFT
 Performed on pre-generated data
 I2C
 LCD refresh takes 58 ms over I2C
 Sleep
 Mode with RTC running chosen
Sleep
SPI
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© 2012 Renesas Electronics America Inc. All rights reserved.
FFT
I2C
Power Profile
Current
GPIO
External Trigger
Port toggle
indicating first
line of code
executed after
wake-up.
SW3 Wake-Up
Trigger
Start of SPI
stage
Start of FFT
stage.
End of SPI
stage
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© 2012 Renesas Electronics America Inc. All rights reserved.
Start of I2C
stage.
End of FFT stage.
End of I2C
stage.
Start of lowpower stage.
Measuring Transient Stage Current
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Low-ohm load resistor (1-2 Ohms)
Voltage drop across resistor using scope probe
Ammeter for steady state current
Combine of these two methods for an accurate picture
© 2012 Renesas Electronics America Inc. All rights reserved.
Measuring Transient Stage Current
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1 nA – 30 mA
200 mV – 5V
Continuous ranging
USB
$900-$1500
pocketpico.com
© 2012 Renesas Electronics America Inc. All rights reserved.
Lab Outline: Sections 1-2
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Measure current draw in each stage
Calculate transition times
Generate power profiles
Plot current vs update rate graph
Determine crossover point
© 2012 Renesas Electronics America Inc. All rights reserved.
Start the Lab: Section 1-2
 Please refer to the lab handout and let’s get started!
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Discussion
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Discussion
0.2 mA
0.4 Hz
MCU
RL78
RX200
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© 2012 Renesas Electronics America Inc. All rights reserved.
Maximum Update/Sec
6.4
14.8
RX210 Operating Modes
 Configured via the OPCCR register
 Module Stop, Software Standby, Deep Software Standby
Mode
ICLK
Max
Freq.
F/PCLK
Max
Freq.
BCLK
Max
Freq.
Flash VCC Range
Limitation
Read Op.
P/E Op.
High Speed Mode
50MHz
32MHz
12.5MHz
5.5-2.7V
Middle Speed Mode A
32MHz/
20MHz
32MHz/
20MHz
8MHz/
5MHz
5.5-1.8V/
1.8-1.62V
Middle Speed Mode B
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5.5-2.7V
Internal Voltage
Regulator Mode
High Power
Middle Power
3.6-1.62V
Low Speed Mode 1
1MHz
1MHz
250kHz
5.5-1.62V
Low Speed Mode 2
32kHz
32kHz
4kHz
5.5-1.62V
© 2012 Renesas Electronics America Inc. All rights reserved.
N.A.
Low Power
Ultra Low
Power
RX210 Wake-Up to HOCO @50MHz from S/W
Standby
 180 uA in S/W Standby
 Wakeup:150 uSec
 Flash powered ON
 HOCO powered ON
 RTC+SUBClk ON
 5uA in S/W Standby
 Wakeup: 580 uSec
 Flash powered OFF
 HOCO powered ON
 RTC+SUBClk ON
 Thus there is a time/power tradeoff choice involved that has
to be made depending on the application
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© 2012 Renesas Electronics America Inc. All rights reserved.
Lab Outline: Section 3
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Add an extra stage to the program
Account for power-down transition stage
Choose a different low power mode
Update graph to determine new crossover point
Use battery calculator to determine battery life
© 2012 Renesas Electronics America Inc. All rights reserved.
Start the Lab: Section 3
 Please refer to the Lab Handout and let’s get started!
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Discussion (0.01 Hz Update Rate)
1000 mAh Battery Life (days)
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RL78
RX210
6414
229
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Discussion (0.1 Hz Update Rate)
1000 mAh Battery Life (days)
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RL78
RX210
699
214
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Discussion (0.4 Hz Update Rate)
1000 mAh Battery Life (days)
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RL78
RX210
176
174
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Discussion (1 Hz Update Rate)
1000 mAh Battery Life (days)
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RL78
RX210
70
127
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Discussion (6 Hz Update Rate)
1000 mAh Battery Life (days)
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RL78
RX210
11
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Discussion
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© 2012 Renesas Electronics America Inc. All rights reserved.
Discussion
MCU – 0.009
RX200Hz
Maximum
Cycles/Sec
Power/Cycle
7 uA sleep and 550 usec wake-up
14.5
0.162mA
186 uA sleep and 150 usec wake-up
14.8
0.157mA
3 uA sleep and 3120 usec wake-up
14.0
0.192mA
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© 2012 Renesas Electronics America Inc. All rights reserved.
Discussion
 What other operational parameters are missing from this
discussion?
 Response time
 Overlapping stages
 Interrupt driven stages
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© 2012 Renesas Electronics America Inc. All rights reserved.
Summary
 How to decide which MCU is better suited to a low power
application
 How to model an application to determine its power profile
 The best low power MCU is the one that best fits the
application
 Low power comparison spreadsheet
 Identify relevant information in the datasheet
 This approach can be used to compare any number of MCUs
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© 2012 Renesas Electronics America Inc. All rights reserved.
Questions?
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© 2012 Renesas Electronics America Inc. All rights reserved.
‘Enabling The Smart Society’ in Review…
 ‘Portable and eventually wearable electronics will be a
hallmark of the Smart Society and powerful, energy efficient
MCUs are a key component of this future’
 Challenge:
“The kind of electronics that would be pervasive in a Smart
Society demand both powerful and highly energy efficient
MCUs; unlike the low-current low-performance MCUs used in
the past”
 Solution:
 “This class will show you how to determine the important
MCU parameters and model the application to determine the
best power vs performance tradeoff in choosing an MCU.”
32
© 2012 Renesas Electronics America Inc. All rights reserved.
Renesas Electronics America Inc.
© 2012 Renesas Electronics America Inc. All rights reserved.