Edward Brorein
Applications Specialist
Optimize Your Mobile Device Run-time using
Innovative Battery Drain Analysis Techniques
Copyright © 2008 Agilent Technologies
A Growing Need for Battery Drain Analysis in R&D
• In Development, optimize battery operating time:
• Evaluate and optimize overall device and its sub circuits
• Validate and optimize battery power management system
• Identify high peak drain anomalies and their root causes
• In Software Development, validate new code builds:
• Run application code regression test suites, impact on battery drain
• In Design Integration and Validation: run suites of benchmark tests:
• Current drain for channels & transmit (TX) power level combinations, & main op modes
• Validate operating time with product’s battery (run-down test)
• Check HW, L1/L2/L3, OS & application interactions on battery drain (stress test)
Benefits:
• Bring smaller, longer running, more competitive products to market
• Faster time-to-market and at lower expense by reducing development time
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
Page 2
1
Typical System for Battery Drain Measurement & Analysis
Challenges:
• Sourcing power with
characteristics of a battery
• Accurate current measurements
• Digitizing and data streaming &
management
• Effective software for analyzing
long-term battery drain data
• Software development effort
that yields a flexible & capable
system
Representative System Platform for Battery Drain Measurement & Analysis
Page 3
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery and DUT Real World Characteristics
DUT Electrical Model
Contact & protector resistance
IL(Vbattery)
+
V-bat (V)
4.5
Vbattery(IL)
* LDO regulators
Cell voltage
Power Amp
V2
Display
Vn
Non-ideal voltage source:
•Charge-dependent resistance
•Charge-dependent voltage
Resistance
mOhms
I - DUT
(mA)
600
120
400
110
200
100
. . .
+
* DC/DC
converters
V1
. . .
Cell internal
resistance
Power
management IC
Audio Amp
Voltage-dependent current
drain characteristic
4.0
V-mp
3.5
3.0
R-mp
0%
50%
100%
% Discharged
3.0
3.5
4.0
4.5
V-bat (V)
• DUT current, battery voltage, and battery resistance are interdependent
•Two types of testing: Fixed battery mid-point and battery run-down
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
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Fixed Mid-point Test; Importance of Emulating a Battery
Response to a GSM Handset in TX Mode
General Purpose
Power Supply Response
Actual Battery Voltage
Response
Battery Voltage
GP-PS Voltage
Instability
Agilent 66319 DC Source
Response
BE-PS Voltage
Unloading
Overshoot
Battery Current
GP-PS Current
Battery mid-point
resistance: 150 milliohms
Resultant current drain does
not match the battery
• 10% higher drain
• Instability & overshoot
BE-PS Current
Battery Emulator output
set to 150 milliohms
• Performance comparable
to a battery
• Unlike a battery
parameters are controlled
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Page 5
Specialized Solution for Measurement Challenges
High Speed, high crest factor pulsed current drain signals and micro ampere to
ampere levels of digital wireless devices pose measurement challenges
Agilent 66319D DC Source simplifies battery drain measurements by eliminating
separate instruments with integrated, specialized current measurement system:
• Accurate Integrated Current Measurement
• Multiple current ranges (5 A, 1 A, and 0.02 A)
• Can source full current while in low measurement ranges
• High-Speed Digitizing System
• High-speed DSP, 16-Bit, 64 kHz ADC and 4,096 byte buffer for waveform digitization
with flexible triggering and data processing
• Works with the 14565B software to continuously process and stream current drain
measurement data for long term data logging
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
Page 6
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Specialized Solution for Analysis Challenges
Creating a solution for effective visualization and detailed analysis of
long-term, high speed sampled current drain data is a large and
challenging software effort
The Agilent 14565B battery drain analysis software is a easy-to-use
graphical interface that works with the Agilent 663xxB/D Mobile
Communications dc Sources:
•
Source, measure, data log, visualize, and analyze current drain
•
Three modes of operation
1. Waveform Capture and Analysis (short-term capture)
2. Data Logging and Analysis (long-term capture)
3. CCDF Statistical Distribution Capture and Analysis (longterm capture)
•
Automation: Control the 14565B from other programs to automate
and synchronize DUT activity with its current drain measurements
Page 7
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Setup for RF and DC Stimulus and Measurement
PC running E6568C Wireless Test Manager
(WTM) SW which is controlling the E5515C
and 14565B SW, and the 14565B SW in turn
controlling the 66319D
GPGP-IB
RF
antenna
cable
8960 Wireless Communications
Test Set emulates base station
and sets up mobile device test
conditions
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
DC power
Device
Under
Test
66319D Mobile Communications
DC Source with high speed
digitizer measures the battery
current drain
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Agilent 14565B Waveform Capture and Analysis of a GSM
TX Pulsed Current
• Oscilloscope-like
view of battery
current drain
• Measurements
permit estimating
operating time and
current drain
• Measurements
include average,
pulse high and peak
levels, and timing
values
• Zoom and markers
for analysis
14565B software displaying a GSM TX current waveform
Page 9
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Insightful Real World Battery Run-down Testing
Output set to 0 volts
Iload
Zero-burden active shunt concept
- out
- out
+ out
+
ILOAD
- in
Vin =
Vbattery
+ in
Iload
VDROP =
ZERO
RSHUNT
DVM in
B+
DUT battery
VSHUNT
-
+ out
ILOAD
+
(1 x VSHUNT)
-
B-
Agilent 66319B DC source output set to zero volts and connected in series
becomes zero burden (zero ohm) active shunt:
• Use actual DUT battery, real world results
• No shunt V drop, DUT sees full battery voltage
• DUT sees actual battery impedance only
• DC source output logs actual battery run-down current
• DVM input (D-suffix option) logs actual battery run-down voltage
• See application note AN 1427 (5988-8157EN) for details
• Gain insight through measuring DUT together with its battery as a system
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
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Battery Run-down Test, Data Logging and Analysis
• 10 ms integration
reduces data while
maintaining accurate
avg. (esp. for zoom)
battery voltage
• Capturing battery
voltage & current gives
greater insights beyond
run time:
peak current
•Tracking peak
current identifies
anomalies
•Achieved capacities
in application vs.
battery spec
average current
minimum current
•Low voltage
shutdown details
GSM handset battery run-down test data log
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Page 11
Battery Run-down Test, Analyzing Low Battery Shutdown
• Zoom to final minutes
of operation
• Shutdown at max
current but not
anomalously high
• 3.50 V shutdown
point appears high
• 3.67V after shutdown
indicates battery
resistance is OK
• Voltage and current
trajectories indicate
near end of battery
capacity
GSM handset battery run-down test, low battery shutdown
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
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Integrating Feature Reduces Data in Real Time
Normal Digitizing
Current
Agilent Data Integration/reduction
Current
Up to 64,000 points Æ 1 data set
Max
Avg
Min
Up to 64,000 data points
time
15.6 μs
0.005 to 1 sec
Sampled
at 64 KHz during
0.005 to 1 sec
time
• 0.005 to 1 second programmable integration period provides a minimum,
maximum, and average value for each period of 64 kHz sampled data.
• Manageable data files for post analysis and export (5 MB per 100 hours)
• Logs data to the disk to reduce loss of test data if test is interrupted
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Page 13
Agilent 14565B Complementary Cumulative
Distribution Function CCDF Capture and Analysis
• CCDF is an alternate
form of a histogram
useful for visualization
and analysis of complex
signals
• Displays current or
voltage on x-axis versus
% occurrence on y-axis
• Horizontal shifts indicate
amplitude related
changes
• Vertical shifts indicate
time related changes
• Zoom, markers, save,
recall and compare for
analysis
• Accumulates from 10
seconds to 1000 hours
• Captures details with
sampling at 64 kHz
CCDF graph of a Bluetoothtm headset talk mode current drain
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
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A CCDF Graph Analysis Example: GSM DTX Operation
• Comparing DTX-off
(red trace) to DTXon (blue trace)
• The time-related
difference is
quickly observed
and quantified
DTX off
12.5%
DTX on
1.5%
• Transmit burst
occurrence drops
from 12.5% to
1.5%
• Overall average
current drain drops
from 319mA to
94mA (71% drop!)
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Page 15
Why Automate Current Drain Measurements?
Some Examples of Where Automation is Useful:
• In Design Validation:
• Test suite of current drain vs. transmit (TX) power levels & channels
• In Software Development:
• Validate against current drain with regression test suites
• Timestamp current drain behavior synchronized to specific DUT activity
• In Integration and Verification :
• Stress testing designs to find issues early in the design cycle
• Perform realistic network testing before network drive tests
• Ensure Product’s meet published specifications & industry benchmarks
• Ensure Product’s meet Service provider sourcing requirement specification
Benefits:
• Reduce Time-to-market - Get product out more quickly and with less resources
• Test early and more thoroughly - Perform tests previously not practical to do
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
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Agilent 14565B Automation Interface Highlights
• Full set of commands implemented using Component Object Model (COM)
automates the 14565B functionality from a client environment
• Client languages include:
Client programs include:
• Visual C++ using MFC
Agilent VEE
• Visual Basic for Apps.
National Instruments Lab View
• Visual Basic 6.0
Agilent Wireless Test Manager (WTM)
• Visual C# (.NET)
• Visual Basic (.NET)
• WTM Driver and integration guide
• Complete programmer’s development folder includes;
• Programming guides, starter programs, automation examples, automation
help file, C++ wrapper, WTM driver and test steps, and more
Page 17
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
SW for Current Drain vs. Channel & TX Level Automation Example
E6568C Define
Test Plan
Test Steps
• RF parameters
• Current Drain
• Custom
Test Plan
• Build RF & Battery Drain
test steps into a test plan
E6568C Run Test Plan
• Sets TX level & Channel
• Measures TX level & battery drain
• Increments & repeats
Program calls automate
battery drain measurements
Benefit: Days/weeks of manually setting & running
tests reduced to a couple of hours for setup
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
Battery drain
data returned
14565B Battery Drain
Measurements
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9
Summary: A Growing Need for Battery Drain Analysis
• In Development, optimize battery operating time:
• Evaluate and optimize overall device and its sub circuits
• Validate and optimize battery power management system
• Identify high peak drain anomalies and their root causes
• In Software Development, validate new code builds:
• Run application code regression test suites, impact on battery drain
• In Design Integration and Validation: run suites of benchmark tests:
• Current drain for channels & power level combinations, & main op modes
• Validate operating time with product’s battery (run-down test)
• Check impact of HW, L1/L2/L3, OS & application interactions on battery drain
Benefits:
• Bring smaller, longer running, more competitive products to market
• Faster time-to-market and at lower expense by reducing development time
HSDS, Battery Drain Copyright © 2008 Agilent Technologies
Battery Drain Analysis
Page 19
10