Cymbet EnerChip User Guide

Cymbet EnerChip™ Smart
Solid State Batteries
Product Overview and
User Guide
AN-72-1026
Version 9.0
AN-72-1026 v9.0
© Copyright 2008-2012 Cymbet Corporation. All rights reserved.
Cymbet Corporation
18326 Joplin St. NW
Elk River, MN 55330
Phone 763-633-1780
www.cymbet.com
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Table of Contents
Table of Contents
ENERCHIP PRODUCT FAMILY OVERVIEW
4
EnerChip CC with integrated battery management
5
DESIGNING WITH ENERCHIPS
6
Circuit Design Techniques
Designing EnerChip Charging Circuits
EnerChip PCB Layout Rules
PCB Layout & Board Contamination EnerChip PCB Package Layouts
Prototyping with the EVAL-05
6
6
8
8
8
9
HANDLING, CHARGING AND STORING ENERCHIPS
10
Guidelines for Handling EnerChips
EnerChip Charging Overview
EnerChip Charging Guidelines
Charging Profile Discharge Cutoff
10
11
12
13
13
PACKAGED ENERCHIP ASSEMBLY TECHNIQUES
14
Chip delivery options
SMT Process Reflow Soldering
Hand Soldering Techniques
14
14
14
15
ENERCHIP BARE DIE HANDLING AND ASSEMBLY 16
Bare Die Delivery Options
Bare Die Handling Guidelines
Die Bumping and Wirebonding
Bare die Temperature guidelines
Bare Die Encapsulation and Underfill Guidelines
16
16
16
17
17
ENERCHIP BARE DIE HANDLING AND ASSEMBLY 17
FACTORY TESTING AND REPAIR AFTER ASSEMBLY
18
In-Circuit Testing of EnerChips EnerChip Assembly Repair Techniques Battery Performance Considerations 18
22
23
ENERCHIP PERFORMANCE CONSIDERATIONS
23
CONTACT INFO
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Chapter One
EnerChip Product
Family Overview
ENERCHIP THIN FILM BATTERIES
Cymbet EnerChip™ smart solid state rechargeable batteries having unique
characteristics relative to conventional rechargeable batteries. EnerChips have a high
charge/discharge cycle life; low self-discharge; simple voltage controlled charging
requirement; flat voltage profile; have no flammable solvents to leak or catch fire; are
solder reflow tolerant; and are offered in low profile surface mount packages.
EnerChips are used in applications requiring backup, bridging, or transition power to
maintain real-time clock operation or SRAM data retention in the event of main power
interruption; wireless sensing as the main power source when energy can be harvested
from the ambient power and used to constantly trickle charge the EnerChip; and as a
power source used to perform housekeeping for microcontrollers and peripherals when
main power is interrupted, to ensure an orderly shutdown or transition to low power
modes.
This User Guide provides the system designer, manufacturing engineer, and end user
with important information on operating characteristics, design guidelines, handling,
storage, assembly, and testing of the EnerChip Smart Solid State Batteries.
To ensure specification integrity across Cymbet EnerChip documentation, detailed
product specifications for each EnerChip or Evaluation kit are contained in the products
associated Data Sheet. The Data Sheets are either on www.cymbet.com or available
directly from Cymbet. Using EnerChips in various applications in conjunction with other
vendor's devices can be found on the Application Notes page http://www.cymbet.com/
design-center/application-notes.php
EnerChips are offered in a variety of sizes and packages ranging from 1uAh to 50uAh
with features and options available to serve a range of applications. Standard products
include:
Figure 1: EnerChip CBC050
and CBC012 Front
CBC012
EnerChip 12µAh Battery
The EnerChip CBC012 is a solid state thin film rechargeable battery. It is designed to
be surface mounted (SMT) and is reflow tolerant. The EnerChip provides thousands of
recharge cycles and has a fast recharge time. The CBC012 is Eco-friendly and has no
harmful gasses, liquids or special handling procedures. It is packaged in a 5 x 5 mm 6-pin
DFN package. Operating temperature is -20°C to +70°C.
Data Sheet: DS-72-02
CBC050
Figure 2: EnerChip CBC050
and CBC012 Back
EnerChip 50µAh Battery
The EnerChip CBC050 is a solid state thin film rechargeable battery. It is designed to
be surface mounted (SMT) and is reflow tolerant. The EnerChip provides thousands of
recharge cycles and has a fast recharge time. The CBC050 is Eco-friendly and has no
harmful gasses, liquids or special handling procedures. It is packaged in an 8 x 8 mm
16-pin QFN package. Operating temperature is -20°C to +70°C.
Data Sheet: DS-72-01
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ENERCHIP CC WITH INTEGRATED BATTERY MANAGEMENT
The EnerChip CC is the world’s first Intelligent Solid State Battery. It is an integrated solution that provides battery backup and power management for systems requiring power
bridging and/or secondary power. A single EnerChip CC can charge up to 10 additional
EnerChips connected in parallel. The EnerChip CC block diagram:
Figure 3: EnerChip
CBC3112 and CBC3150
CBC3112
EnerChip CC 12µAh with Integrated Battery Management
The EnerChip CC is the world’s first Intelligent Thin Film Battery. It is an integrated solution
that provides battery backup and power management in systems requiring power bridging
and/or secondary power. A single EnerChip CC CBC3112 can charge up to 10 additional
EnerChips connected in parallel. It is packaged in a 20-pin 7 x 7 mm DFN package for
SMT and is reflow tolerant.
Figure 4: EnerChip CBC3112
and CBC3150 Back
Data Sheet: DS-72-04
CBC3150
EnerChip CC 50µAh with Integrated Battery Management
The EnerChip CC is the world’s first Intelligent Thin Film Battery. It is an integrated solution
that provides battery backup and power management in systems requiring power bridging
and/or secondary power. A single EnerChip CC CBC3150 can charge up to 10 additional
EnerChips connected in parallel. It is packaged in a 20-pin 9 x 9 mm DFN package for
SMT and is reflow tolerant.
Data Sheet: DS-72-03
CBC-EVAL-05
EnerChip CC Evaluation Kit
The EnerChip CC EVAL-05 evaluation kit contains both an EnerChip CC CBC3112 and
an EnerChip CC CBC3150. Either Enerchip CC can be tested standalone, either internal
Enerchip battery may be tested alone, or either EnerChip CC can control itself and the
thin film battery in the other EnerChip CC. The EVAL-05 is packaged as a 24-pin DIP that
can be socketed on a test board.
Figure 5: CBC-EVAL-05
Evaluation Kit
Data Sheet: DS-72-09
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Chapter Two
Designing with
EnerChips
CIRCUIT DESIGN TECHNIQUES
EnerChips are used much in the same way as legacy storage devices such as capacitors and coin cells. The EnerChip CBC012 and CBC050 have a Positive Terminal
and Negative Terminal (normally tied to a Ground Potential) similar to these other
devices.
DESIGNING ENERCHIP CHARGING CIRCUITS
EnerChip thin film rechargeable batteries are conducive to a variety of charge
control circuits. The recommended charging voltage is a constant 4.1V. The range
from 4.1V to 4.3V is acceptable, but the number of life charge cycles will be reduced
toward the top of the range. The range from 4.0V to 4.1V is also acceptable, but the
full charge will be reduced toward the bottom of the range. The range of acceptable
charging voltages is illustrated in Figure 14.
Circuits consisting of one or more diodes and a fixed power supply may be used;
however, fluctuations in the power supply voltage and part-to-part variability in the
diode voltage drop will affect the voltage across the battery terminals.
CIRCUIT SCHEMATIC EXAMPLES
The following three figures present examples of how the EnerChip CC is used in
conjunction with microcontrollers and real-time clocks. These designs are fairly
straight forward due to the highly integrated capabilities of the EnerChip CC. For
applications requiring high pulse current outputs, please refer to Application
Note AN-72-1025. For applications using the "brown-out" feature of several
microcontrollers, please refer to Application Note AN-72-1027.
Figure 6: Typical EnerChip CC Microcontroller Backup
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Figure 7: EnerChip CC Providing Real-Time Clock Power Backup
Figure 8: EnerChip CC Providing Power Management for Multiple EnerChips
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ENERCHIP PCB LAYOUT RULES
There are several PCB layout considerations that must be taken into account when
using the EnerChip:
1. All capacitors should be placed as close as possible to the EnerChip.
2. Power connections should be routed on the layer the EnerChip is placed.
3. The flying capacitor connections must be as short as possible and routed on
the same layer the EnerChip is placed.
4. A ground (GND) plane in the PCB should be used for optimal performance of
the EnerChip.
5. Very low parasitic leakage currents from the VBAT pin to power, signal, and
ground connections, can result in unexpected drain of charge form the
integrated power source. Maintain sufficient spacing of traces and vias from
the VBAT pin and any traces connected to the VBAT pin in order to eliminate
parasitic leakage currents that can arise from solder flux or contaminants on
the PCB.
6. On the EnerChip CC, Pin 1 VBAT and Pin 4 VCHG must be tied together for
proper operation.
PCB LAYOUT & BOARD CONTAMINATION
•
•
•
Figure 9: CBC012 PCB traces
resulting in a low resistance
leakage path.
•
•
Electrical resistance of solder flux residue can be low enough to discharge the
cell at a much higher rate than in the normal backup mode. Therefore, solder
flux must be thoroughly washed from the board following soldering.
The PCB layout can make this problem worse if the cell’s positive and negative
terminals are routed near each other and under the package, where it is
difficult to wash the flux residue away.
In the example in Figure 9, the negative connection is routed from the negative
pad to a via placed under the package near the positive pad. In this scenario,
solder flux residue can wick from the positive solder pad, covering both the
positive pad and the via, resulting in a high resistance current path. This
current path will make the cell appear to be defective or make the application
circuit appear to be drawing too much current. Avoid placing vias beneath the
EnerChip package.
Make sure positive and negative traces are routed outside of the package
footprint to ensure that flux residue will not cause a discharge path between
the positive and negative pads.
See the section on assembly repair techniques for additional information on
board layout guidelines.
ENERCHIP PCB PACKAGE LAYOUTS
Each EnerChip data sheet shows the details of each chip package. Refer to the data
sheet for the EnerChip you are using for PCB layout guidelines specific to that device
and package. Note that although some of the EnerChip packages have an exposed
center die pad on the bottom of the package, it is strongly recommended that the PCB
NOT have a corresponding solder pad to align with the center pad on the package.
Again, this is to reduce the number and severity of leakage paths between the battery
terminals.
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PROTOTYPING WITH THE EVAL-05
The first step in using the CBC-EVAL-05 evaluation kit is to read the data sheet DS-72-09
for all the technical specifications and interface descriptions.
To connect the EVAL-05 to a power source and a target load, insert the 24-pin DIP EVAL05 as shown in Figure 10 into a socket or proto-board. Connect the other devices as
shown in the EVAL-05 data sheet.
The EVAL-05 can be used in 7 different modes. Please refer to the EVAL-05 data sheet
for the connections for the other 6 modes.
The EVAL-05 EnerChip CC CBC3112 and CBC3150 devices are charged at the factory,
so there should be about a 50% state of charge on both devices. Any charging time
required to enable the application should be minimal.
VBAT
VOUT
VDD
1
24
2
23
3
22
VCHRG
ENABLE
VMODE
GND
RESET
CP
CN
NC
NC
4
21
5
20
6
19
7
18
8
17
9
16
10
15
11
14
12
13
NC
NC
CN
CP
RESET
GND
VMODE
ENABLE
VCHRG
VDD
VOUT
VBAT
24-Pin DIP Module
Figure 10: Pin configuration of
EVAL-05 24-pin DIP Board.
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Chapter Three
Handling, Charging
and Storing
EnerChips
GUIDELINES FOR HANDLING ENERCHIPS
Cymbet™ EnerChip™ thin film, solid state batteries feature all solid state
construction, are packaged in standard integrated circuit packages, and can be
reflow soldered for high volume PCB assembly. They are ideal as rechargeable
backup power sources for clocks, memories, microcontrollers and other low-power
circuits where data or timing information must be retained in the absence of
primary power.
This document provides general handling guidelines and precautions for
the batteries. These include device handling and storage, protection against
electrostatic discharge (ESD), reflow solder, and in-circuit use.
Device Handling & Storage
• EnerChip batteries are packaged and shipped in moisture barrier bags, and
are sensitive to moisture absorption. They must be kept in the sealed bag
until ready for board mounting and reflow soldering.
• If the batteries are removed from the sealed bag more than 168 hours prior
to board mounting, they must be baked at 125°C for a minimum of 24
hours prior to board mounting and reflow soldering.
• Store the batteries in an environment where the temperature and humidity
do not undergo large fluctuations. Store at 10°C to 30°C and at less than
60% relative humidity.
Electrostatic Discharge (ESD)
• Similar to integrated circuits, the batteries are sensitive to ESD damage
prior to receiving a charge cycle. Therefore, adherence to ESD prevention
guidelines is required.
• Remove devices from protective shipping and storage containers at
approved ESD workstations only.
• All equipment used to process the devices must be configured to minimize
the generation of static charges. This includes soldering and de-soldering
equipment and tools, pick-and-place equipment, test equipment, and all
other tools and equipment used to handle or process the devices.
• Failure to observe these precautions can lead to premature failure and
shall void product warranty.
In-circuit Use Guidelines
• Do not connect these batteries to other types of batteries except through an
approved charging circuit.
• To increase battery life, avoid installing near devices that would generate
heat exceeding the 70°C operating limit.
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ENERCHIP CHARGING OVERVIEW
Cymbet™ EnerChip™ thin film, solid state batteries feature all solid state construction,
are packaged in standard integrated circuit packages, and can be reflow soldered for
high volume PCB assembly. They are ideal as rechargeable backup power sources for
clocks, memories, microcontrollers and other low-power circuits where data or timing
information must be retained in the absence of primary power.
The charging time of EnerChip batteries is short compared to that of conventional
rechargeable batteries.
Figure 11 shows the typical percentage of full charge vs. time during constant voltage
charging. Figure 12 shows the EnerChip allowable charging voltage range.
120
Percent Charged
100
80
60
40
20
0
0
10
20
30
40
50
60
Time (minutes)
Figure 11: Typical Battery Charging Profile; Vc = 4.1V
Figure 12: Allowable Charging Voltage Range
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ENERCHIP CHARGING GUIDELINES
As with other rechargeable batteries, discharge capacity and cycle life are a function
of charge voltage, discharge cutoff voltage, depth-of-discharge, temperature, and
other factors. The system designer must understand the effect of these factors
when designing the charge control circuit.
•
Never apply more than 4.3V across the battery terminals. There is no need
to externally limit the charging current of small surface-mount batteries.
The intrinsic cell resistance is sufficient to limit the current to an acceptable
level as long as the applied voltage does not exceed 4.3V.
The charging voltage and charge time determine the amount of charge
delivered to, and accessible from, the battery. A higher charging voltage
will deliver more charge, but will also result in greater long-term capacity
fade as a function of charge/discharge cycling. Figure 13 shows trade-offs
between charging voltage, charge capacity and cycle fade.
The batteries may be charged at a constant current (CC) followed by a
constant voltage (CV). During the CC phase, the current may be set to any
value that results in an acceptable charging time and does not cause the
battery voltage to exceed 4.3V.
CV charging will normally result in faster charging times than the combined
CC-CV approach. The latter may become necessary with future, larger
batteries with lower intrinsic cell resistance. Please refer to the data sheets
of these batteries.
•
•
•
60
Achieved Capacity (µAh)
50
40
4.3V
4.2V
4.15V
4.1V
4.0V
30
20
10
0
0
10
20
30
40
50
60
70
80
90
100
Cycles
Figure 13: Effect of Charging Voltage on Battery Charge and
Cycle Fade
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CHARGING PROFILE
Figure 14 shows the charging current input in microamperes divided by the EnerChip
capacity in microampere-hours. As indicated, the EnerChip is at 80% charge in about 30
minutes.
Current in µA / Capacity in µAh
4.0
3.0
2.0
1.0
0.0
0
10
20
30
40
50
60
Time (minutes)
Figure 14: Charging Circuit with a Linear Regulator
DISCHARGE CUTOFF
In order to preserve the cycle life and other performance characteristics of the EnerChip,
it is important to terminate the battery discharge when the battery voltage reaches 3V.
This is particularly important when discharging at very low current – for example, below
a few microAmperes. Although > 90% of the battery capacity will have been depleted
when the battery voltage reaches 3V at low drain current, the battery will nevertheless
continue to supply current below 3V. If discharged continuously below that voltage, the
battery will be damaged.
Simple circuits utilizing a discrete or MCU-embedded reference voltage to control a
series FET switch, for example, could be used to disconnect the load when the battery
voltage reaches 3V.
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Chapter Four
Packaged
EnerChip Assembly
Techniques
CHIP DELIVERY OPTIONS
EnerChips are delivered from the factory in one of three package types:
•
•
•
Tube - EnerChips are packaged in anti-static tubes that are compatible with
automated assembly equipment using surface mount technology.
Tape and Reel - EnerChips are packaged in 1000 piece lots on a tape and
reel for use with automated assembly equipment using surface mount
technology.
Waffle Pack - EnerChips are placed in individual chambers in a waffle pack
tray for manual assembly or automated pick and place assembly.
SMT PROCESS
The EnerChips are packaged in standard surface mount packages. Refer to the
solder paste material data sheets for attachment of the package to a PCB using
solder reflow processes. Ensure that the solder reflow oven is programmed to the
correct temperature profile prior to assembling the EnerChip on the PCB.
REFLOW SOLDERING
•
•
•
The maximum number of times the battery may be reflow soldered is three
times.
The surface temperature of the battery must not exceed 260°C.
The recommended solder reflow profile is shown in Figure 15 below; refer to
Figure 16 for time and temperature requirements. Whenever possible, use
lower temperature solder reflow profiles.
Figure 15: EnerChip Solder Reflow Profile
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Parameter
Sn/Pb
Pb-free
6°C/sec
6°C/sec
Soak temperature, min, TSMIN
135°C
150°C
Soak temperature, max, TSMAX
155°C
200°C
Soak time, max, tS
2 min
3 min
Liquid temperature, TL
183°C
220°C
Max time above tL
150 sec
150 sec
Max peak temperature, TP
220°C
260°C
Max time at peak, tP
225°C
260°C
Max ramp-down rate
10°C/sec
10°C/sec
Max ramp-up rate
Figure 16: Solder Reflow Parameters
HAND SOLDERING TECHNIQUES
When soldering the EnerChip using by hand at a soldering station, adhere to the following guidelines:
•
•
•
•
•
•
Observe the ESD precautions outlined in this document.
Never solder an EnerChip that has been partially or fully charged, even if the
EnerChip is in a discharged state. This includes wave soldering and reflow
soldering.
Minimize the amount of time that heat is applied to the EnerChip. Using a
tweezer-type soldering iron tip that applies heat to two opposite sides or the
entire perimeter of the device simultaneously will result in more uniform
heating of the package and for a shorter period of time than when soldering
one pin or package edge at a time.
If possible, apply solder paste to the solder pads on the PCB prior to placing the
EnerChip on the board; this will promote wetting of the solder and reduce the
amount of time the soldering iron is applied to the component and solder pads.
Place the EnerChip onto the PCB by hand and solder in place rather than
grabbing the EnerChip with a heated tweezer-type tip and placing the EnerChip
on the board with the iron. This will minimize the amount of time the EnerChip
is exposed to heat.
Most surface mount packages have metal leadframe tie points that do not
extend to the bottom surface of the package but are exposed on two more of
the package sidewalls. When soldering, ensure that solder does not cover these
tie points, as this situation could result in package pins being shorted to one
another through the metal leadframe.
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Chapter Five
EnerChip Bare
Die Handling and
Assembly
BARE DIE DELIVERY OPTIONS
EnerChip bare die applications often require custom procedures and significant
variation exists among package vendors and assembly equipment, making specific
guidelines difficult. Contact Cymbet Application Engineering to review handling,
wirebonding, bumping, and assembly guidelines.
Bare die undergo the following screening procedures prior to leaving the manufacturing facility:
•
•
Electrical test to ensure the cell is not shorted, open, and is within the
specification limits of cell resistance.
MIL-STD-883 optical inspection.
BARE DIE HANDLING GUIDELINES
•
•
•
•
•
•
When unpacking, storing, inspecting, or handling bare die Enerchips, all
operations should be performed in a Class-1,000 (or better) clean room - ISO 6
equivalent.
When removing die from waffle packs, use the minimum downward force
possible with the handling mechanism.
Handling and insertion forces need to be kept to a minimum to reduce damage
to the device materials.
Tool recommendations: Use pick-and-place tool having a “soft” tip, e.g., rubber
or other pliable material.
EnerChips are sensitive to electrostatic discharge (ESD) and should always be
handled in an ESD-controlled environment and in accordance with the ESD
guidelines set forth in Chapter 3.
EnerChips should be stored in a humidity-controlled environment to prevent
excess moisture from penetrating the EnerChip.
DIE BUMPING AND WIREBONDING
EnerChip bare die have bond pads that are suitable for either wirebonding or bumping. The pad structure is typically designed for one or the other attachment methods, but not both. Pads are made of aluminum with a small amount of silicon and
copper and therefore either gold or aluminum wires may be attached to the bond
pad. Pads designed for bumping can be stud bumped or solder bumped.
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Standard wirebond machine and process settings are generally applicable when
wirebonding to EnerChip die. When placing EnerChip die onto the die attach material,
use the minimum downward force possible. Ensure there is a uniform coating of die
attach material on the substrate (i.e., no voids or gaps) and that the die attach material
extends to the edge of the EnerChip die during die placement.
Chapter Five
EnerChip Bare
Die Handling and
Assembly
Recommended wirebond process time and temperatures are as follows:
Die Attach Epoxy Cure
190°C +/- 10°C for 1.5 hours
Wirebond
Pre-heat: 190°C
Wirebond: 200°C
Post-heat: 190°C
Package Epoxy Cure
175°C +/- 10°C
BARE DIE TEMPERATURE GUIDELINES
Temperature Guidelines:
• Operating temperature: -20°C to +70°C.
• Storage temperature (uncharged): -40°C to +125°C.
• Bare die assembly process temperatures: Do not exceed +200°C for duration
consistent with die attach, wire bond & mold compound cure periods.
BARE DIE ENCAPSULATION AND UNDERFILL GUIDELINES
EnerChip die undergo a minute amount of expansion and contraction when being
charged and discharged. Consequently, it is important to not encapsulate the die with
overly compressive or rigid materials. Similarly, application of rigid epoxy underfill
compounds between a flip-chipped die and printed circuit board material is discouraged.
Contact Cymbet to discuss any encapsulation or underfill requirements and a joint
evaluation will be conducted.
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Chapter Six
Factory Testing
and Repair After
Assembly
IN-CIRCUIT TESTING OF ENERCHIPS
Once the EnerChip has been soldered to a circuit board, it may be charged. If
in-circuit testing is to be done for purposes of testing the EnerChip itself or other
circuitry on the board, the following guidelines should be observed:
•
•
•
Never apply a voltage outside the rated charge or discharge voltage range as
specified in the respective EnerChip data sheet.
As with all batteries, the EnerChip has an inherent internal resistance. Never
force a current into or out of the EnerChip that would result in the battery
voltage rising above or falling below a voltage outside the rated charge or
discharge voltage range as specified in the data sheet.
Once the EnerChip has been charged - partially or fully - do not store or operate
the EnerChip outside of the operating temperature range as specified in the
data sheet.
GUIDELINES FOR IN-CIRCUIT TESTING OF ENERCHIPS
Objective: Verify EnerChip device connectivity after reflow solder process. It is
important to read and understand the proper test flow for the EnerChip devices.
Following the proper test method will ensure reworkability of boards.
Due to the chemistry and construction of the EnerChip products, reflow soldering
of EnerChip components must only be done prior to an initial charge. After the
EnerChip device has been charged – even if subsequently discharged – care must
be given to not expose the device to temperatures in excess of the rated operating
temperature, such as temperatures reached during reflow solder assembly. Often,
components and their connections to the printed circuit board must be tested before
the product is shipped. Moreover, accommodation must be made for post-assembly
rework of components on the board. Localized heating during removal of nearby
components - such as can occur from solder pencils and localized SMT reflow tools
and techniques - can destroy the EnerChip. Rework processes usually include one
or more additional passes through the reflow solder process. Consequently, an incircuit test method for the EnerChip must meet the following criteria:
1. Must be performed relatively quickly so as not to impede product assembly
throughput.
2. Must be testable with standard automated test equipment and instruments.
3. Must provide results indicating that the EnerChip device is functional and
properly connected to the circuit.
4. Must permit the EnerChip device to meet the rated electrical specifications
after being subjected to additional reflow solder processes such as might be
required when other components on the board are being reworked.
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EnerChip devices are tested at the factory using proprietary test to ensure a very low
field failure rate. However, as with any energy storage or semiconductor device, failures
do occur as a result of any number of causes, including improper handling, electrostatic
discharge (ESD), operating beyond rated specifications, etc.
If the board under test is to be reworked and reflowed due to a failure of any device on
this board other than the EnerChip device it is important to follow the test flow exactly.
The EnerChip device may be reflowed up to three times as with most semiconductor
devices. However, once the EnerChip device is charged, the user may not reflow the
part again without replacing it.
EnerChips fall into one of two general categories:
1. Those with integrated power management – typically designated as CBC31xx
products (e.g., CBC3112, CBC3150).
2. Those without integrated power management – typically designated CBCxxx
products (e.g., CBC012, CBC050).
The procedures shown in Figure 18 address all products in both categories and are
intended to provide the test engineer with sufficient responses to declare that the
EnerChip is connected to the circuit and that it is behaving as an energy storage
device. The test procedures described herein do not include the test characterization
necessary to ensure that the EnerChip device conforms to the electrical specifications
as described in the respective data sheets.
The EnerChip test methods described herein are designed to provide the test engineer
with flexibility with respect to charge time, discharge time, and selection of test limits
in order to accommodate various types of test equipment, resolution of measuring
instruments, and the allowable test time. The following graph depicts the timedependent and temperature-dependent voltage of the EnerChip after applying a 4.1VDC
charging voltage for approximately one second, followed by a brief discharge at a
specific load resistance. Using this graph as a guide, the test engineer can develop a
simple test that is feasible with the available test equipment and fixtures and meets the
production throughput needs.
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The chart in Figure 17 should be referenced to determine the voltage on the VCHG/
VBAT pin to be expected after driving the ENABLE pin high for one second. The decay
curves in the chart represent specific load impedances as might be encountered
with Automated Test Equipment (ATE). Additionally, the decay curves represent the
span of EnerChip cell impedances as specified in the respective data sheets. The
test engineer has the freedom to choose a point on the discharge curve that falls
within the parameters of test throughput and equipment measurement capability.
In order for the EnerChip to be considered as meeting the gross functional test
specification, the voltage on the VCHG/VBAT pin must be above the value indicated
by whichever line is chosen as the reference line. Data at two temperatures is
shown in order to encompass the anticipated factory test floors. Note the influence
of temperature on the EnerChip test discharge voltage when setting the test
specification pass/fail limits.
EnerChip Charge-Discharge Profiles for Setting Post-Assembly Test Limits
4.5
75K Ohm Load, 20 Degrees C
75K Ohm Load, 30 Degrees C
806K Ohm Load, 30 Degrees C
EnerChip Voltage (VDC)
4.0
806K Ohm Load, 20 Degrees C
3.5
3.0
2.5
2.0
0.0
0.5
1.0
1.5
2.0
2.5
Charge-Discharge Time (seconds)
Figure 17: Voltage Determination on the VCHG/VBAT Pin
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Figure 18: Factory In-circuit EnerChip Post Assembly Test Steps
1.0
1.1
Precautions
Follow ESD safe handling protocol.
2.0
CBC31xx In-Circuit Test Procedure
2.1.
Apply 4.1VDC to the positive EnerChip terminal, with respect to the negative terminal (i.e., ground), for one second.
2.2.
To ensure that the battery cell inside the CBC31xx is not charged during test it is important that the user force the EN pin on the CBC3150 to a logic low before performing board level testing. WARNING: If the enable pin is asserted for more than 1 second with the VDD > 2.5 volts the CBC3150 cannot be reflowed again. Therefore all other components should be tested and reworked prior to testing the CBC3150.
2.3.
Perform test at room temperature.
2.4.
Force EN pin of CBC31xx to GND.
2.5.
Enable power domains under test.
2.6.
Run all vectors to ensure proper functionality of all semiconductor devices.
2.7.
The device powered by the CBC31xx can be tested at this time.
2.8.
Force the VMODE pin to GND in 3.3V systems; force VMODE pin to VDD in 5V systems.
2.9.
Force VBAT to be electrically tied to VCHG. Typically this is already done on the board, as VBAT must be tied to VCHG in order for the internal battery to be connected to the power management circuit.
2.10.
Apply voltage to VIN that is in the range of 2.5V to 5.5V. (Note: VIN = VDD.)
2.11.
Verify that the VBAT/VCHG net is 4.1 volts +/- 0.025 volts.
2.12.
Allow one second for the battery to charge a very small amount by leaving the device in the above noted configuration.
2.13.
Remove VDD and begin tracking elapsed time.
2.14.
Verify that the VBAT/VCHG not is greater than the value as shown in the fore
going discharge curves.
3.0
3.1.
3.2
3.3
3.4
3.5
3.6
3.7
3.8
CBC31xx Battery Backup Verification: Optional Board/System Level Test. (1)
Power up board or system.
Ensure that CBC31xx EN pin is asserted and VDD is > 2.5 volts.
Allow battery to charge for several minutes.
Program device to be battery-backed.
Remove power for at least several seconds to one minute.
Power up board or system.
Read device formerly under battery backed mode.
Verify device contents.
Notes:
(1)
This test does not verify the actual battery capacity. In order to verify actual capacity the device must be charged for at least one hour and discharged into the battery-backed device.
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ENERCHIP ASSEMBLY REPAIR TECHNIQUES
Should the need arise to replace an EnerChip that has already been soldered to a
circuit board, due to battery failure, improper package placement, or other circumstances, it is recommended that the EnerChip being replaced be discarded and
replaced with a new EnerChip. When removing the EnerChip from the board, use a
tweezer-type soldering iron tip that heats opposite sides of the package simultaneously and lift the package from the board. When applying the new EnerChip to the
board, follow the hand soldering guidelines in the previous section.
For QFN-style packages, use a hot air rework station to remove a defective or misplaced EnerChip package. If there are other EnerChips in the vicinity of the EnerChip
being replaced, use proper heat shielding to protect the adjacent EnerChip package
from the heat source and turn off any heat source that would otherwise be used to
heat the bottom of the board during removal of the EnerChip. This will prevent the
adjacent EnerChip(s) from being damaged during the rework procedure.
If it is not possible to replace the EnerChip with a new EnerChip, use extreme care
when removing the EnerChip from the board to minimize the amount of time heat is
applied to the package during removal and re-soldering. Follow the guidelines in the
previous section pertaining to hand soldering. Under no circumstances should an
EnerChip that has been partially or fully charged - even if subsequently discharged be subjected to reflow, wave, or hand soldering.
Conductive epoxy may also be used as an attachment method. If the cure temperature is above 70°C, then a new (i.e., never charged) EnerChip must be used.
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BATTERY PERFORMANCE CONSIDERATIONS
There are several considerations that must be taken into account that determine EnerChip performance over time and with use. These are:
1. Temperature
•Battery aging accelerates with increasing temperature.
•Note that storage temperatures and operating temperatures are specified for the EnerChip in the device data sheet. The operating temperature range is narrower than the storage temperature range; moreover, the storage temperature range for an EnerChip that has never been charged is different from that of an EnerChip that has been charged one or more times - partially or fully.
•Battery impedance increases with decreasing temperature - by a factor of
approximately 1.5 to 2 for every 10°C reduction in operating temperature.
Chapter Seven
EnerChip
Performance
Considerations
2. Depth-of-Discharge
•As the depth -of-discharge on the cell increases (i.e. lower state-of-charge), the charge/discharge cycle life decreases. See the respective data sheet for charge/discharge cycle life under various operating conditions.
3. Number of Charge/Discharge cycles
•The charge/discharge cycle life of the EnerChip is dependent on a number of
variables, including temperature, depth-of-discharge, charging voltage, and
discharge cutoff voltage. Consult the EnerChip data sheet for specific details.
4. Input Charging Conditions
•It is important to regulate the charging voltage applied to the EnerChip in order to ensure a long service life and delivery of the rated capacity.
5. Discharge Cutoff Conditions
• During discharge of the EnerChip, the minimum discharge cutoff voltage as
specified in the data sheet must be enforced. If the discharge voltage is allowed
to drop below the rated value, particularly at low discharge currents, The
performance of the EnerChip will be degraded, and under certain conditions,
the device will ultimately fail to operate according to specifications.
6. In regards to resistance to Humidity, Chemical exposure, and G-Forces, the
EnerChip product family is designed to meet JEDEC standards.
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Warranty Info
Patent Info
Trademark Info
Contact Info
Disclaimer of Warranties; As Is
The information provided in this data sheet is provided “As Is” and Cymbet Corporation
disclaims all representations or warranties of any kind, express or implied, relating to this data
sheet and the Cymbet EnerChip product described herein, including without limitation, the
implied warranties of merchantability, fitness for a particular purpose, non-infringement, title,
or any warranties arising out of course of dealing, course of performance, or usage of trade.
Cymbet EnerChip products are not authorized for use in life critical applications. Users shall
confirm suitability of the Cymbet EnerChip product in any products or applications in which the
Cymbet EnerChip product is adopted for use and are solely responsible for all legal, regulatory,
and safety-related requirements concerning their products and applications and any use of the
Cymbet EnerChip product described herein in any such product or applications.
U.S. Patent No. 8,144,508. Additional U.S. and Foreign Patents Pending
Cymbet, the Cymbet Logo, and EnerChip are Cymbet Corporation Trademarks. All
other brands and product names are trademarks of their respective companies.
For Additional Documentation: www.cymbet.com
• Design Center
• Application Notes
• Data Sheets
• Schematics • White Papers
• Sales Offices and Distributors
• Request for Quotations
Applications Support: +1 763-633-1780
Email Support: http://www.cymbet.com/design-center/support.php
The Support form is an easy way to document your information
request and have this tracked in the Cymbet case management
system.
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