CBC34803 EnerChip™ RTC

Preliminary
CBC34803 EnerChip™ RTC
I2C Real-Time Clock/Calendar with Integrated Backup Power
Features
• Ultra low power Real Time Clock with Integrated
rechargeable EnerChip™ solid state battery,
power-fail detect and automatic switchover,
providing greater than 5 days (typical) of RTC
backup
• 5mm x 5mm x 1.4mm QFN package is the
smallest commercially available RTC having
integrated backup battery power
• Temperature-compensated charge control
• Integrated EnerChip™ recharged at VDD > 2.5V
• SMT assembly - lead-free reflow solder tolerant
• Counters for hundredths, seconds, minutes,
hours, date, month, year, century, and weekday
based on a 32.768 kHz oscillator
• Automatic leap year calculation
• Alarm capability on all counters
• 2 general purpose outputs
• 64 bytes of RAM
• Advanced crystal calibration to ± 2 ppm
• Advanced RC calibration to ± 16 ppm
• Automatic calibration of RC oscillator to crystal
oscillator
• I2C-bus (up to 400kHz)
• Eco-friendly, RoHS compliant - tested
Applications
• Power bridging to provide uninterruptible RTC
function during exchange of main batteries.
• Consumer appliances that have real-time
clocks; provides switchover power from main
supply to backup battery.
• Ultra Low Power Timers using only 35nA can be
implemented with the CBC34803
• Wireless sensors and RFID tags and other
powered, low duty cycle applications.
• Business and industrial systems such as:
network routers, point-of-sale terminals, singleboard computers, test equipment, multi-function
printers, industrial controllers, and utility meters.
• Time keeping application
• Battery powered devices
• Metering
• High duration timers
• Daily alarms
• Low standby power applications
5mm x 5mm x 1.4mm 16-pin QFN Package
General Description
The EnerChip RTC CBC34803-M5C combines a
Real-Time Clock (RTC) and calendar optimized
for low power applications with an integrated
rechargeable solid state backup battery and all power
management functions. The EnerChip RTC ensures
a seamless transition from main power to backup
power in the event of power loss. The integrated
power management circuit ensures thousands of
charge-discharge cycles from the integrated EnerChip
and manages battery charging, discharge cutoff,
power switchover, and temperature compensation
to maximize the service life of the device. The
CBC34803 provides greater than 5 days of backup
time in the event main power is interrupted. Longer
backup time can be achieved by adding an external
EnerChip to the VCHG pin. The integrated EnerChip
recharges quickly, has extremely low self-discharge, is
non-flammable, and RoHS-compliant. The EnerChip is
charged automatically anytime VDD is above 2.5V.
Data is transferred serially via an I2C-bus. Alarm and
timer functions provide the option to generate a
wake-up signal on an interrupt pin.
XI
XO
Figure 1: CBC34803 Pin-out Diagram
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Preliminary
CBC34803 EnerChip™ RTC
Figure 2: Functional Block Diagram of CBC34803 (AM0803) Real-Time Clock
Figure 3: Internal Schematic of CBC34803 EnerChip RTC
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Preliminary
CBC34803 EnerChip™ RTC
CBC34803 Input/Output Descriptions
Pin Number
Label
Description
1
2
3
4
5
XO
VOUT
nIRQ2
NC
VSS
6
VCHG
7
VEC
8
SDA
Crystal output
CBC910 VOUT
Interrupt 2 / Output
No connection
Ground
4.1V (typical) charging source - connect to VEC (and to optional EnerChip
bare die battery for extended backup time if used)
Positive terminal of integrated thin film battery - connect only to VCHG via
PCB trace
I2C data input / Output
9
10
NC
SCL
No connection
I2C clock input
11
12
AF
FOUT/nIRQ
13
VDD
14
RESET/
Autocalibration filter
Interrupt 1 / Function output - (note this is an open drain output)
Supply voltage; positive or negative steps in VDD can affect oscillator performance; recommend 100nF decoupling close to the device
Output signal indicating RTC is operating in backup power mode
15
EN
Charge pump enable; activates VCHG 4.1V (typ.) charging source
16
XI
Crystal input
Package
Dimensions
(mm)
Figure 4: CBC34803 Package (left: top view, looking through package; right: pad dimensions)
EnerChip Properties
Energy capacity (typical): Recharge time to 80%:
Charge/discharge cycles: Operating temperature:
Storage temperature:
Minimum VDD to charge EnerChip:
5µAh
<15 minutes
>5000 to 10% depth-of-discharge
-10°C to +70°C
-40°C to +125°C
2.5V
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Preliminary
CBC34803 EnerChip™ RTC
Absolute Maximum Ratings
PARAMETER / PIN
CONDITION
MIN
TYPICAL
MAX
UNITS
GND - 0.3
GND - 0.3
-
3.6
V
ENABLE Input Voltage
25°C
25°C
-
VDD+0.3
V
VEC
25°C
3.0
-
4.15
V
25°C
3.0
-
4.15
V
RESET Output Voltage
25°C
GND - 0.3
-
2.7
V
VOUT
25°C
GND - 0.3
-
3.6
V
VDD with respect to GND
(1)
VCHG
(1)
XI, XO, SDA, SCL, AF, FOUT/nIRQ,
nIRQ2
(1)
See Ambiq Micro AM0803 Data Sheet
No external connections to these pins are allowed, except parallel EnerChips for extended backup time.
Integrated EnerChip Thin Film Battery Operating Characteristics
PARAMETER
Self-Discharge (5 yr. average)
CONDITION
MIN
TYPICAL
MAX
UNITS
Non-recoverable
-
2.5
-
% per year
Recoverable
Operating Temperature
-
-10
1.5
25
+70
% per year
°C
Storage Temperature
-
-40
-
+125 (2)
°C
10% depth-of-discharge
5000
-
-
cycles
Recharge Cycles
(to 80% of rated
capacity)
25°C
40°C
Recharge Time (to 80% of rated
capacity; 4.1V charge; 25°C)
Capacity
(1)
50% depth-of discharge
1000
-
-
cycles
10% depth-of-discharge
2500
-
-
cycles
50% depth-of-discharge
500
-
-
cycles
Charge cycle 2
-
11
22
Charge cycle 1000
-
45
70
40nA discharge; 25°C
5
-
-
(1)
First month recoverable self-discharge is 5% average.
(2)
Storage temperature is for uncharged EnerChip CC device.
minutes
µAh
Note: All specifications contained within this document are subject to change without notice.
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CBC34803 EnerChip™ RTC
POWER SUPPLY CURRENT CHARACTERISTICS OF INTEGRATED CBC910 POWER
MANAGEMENT CIRCUIT ONLY
Ta = -20ºC to +70ºC
CHARACTERISTIC
Quiescent Current
(CBC910 power
management circuit
only; VDD > VRESET ; RTC
current not included)
EnerChip Cutoff Current
(IQBATON adds to RTC
current when in backup
mode)
SYMBOL
CONDITION
ENABLE=GND
IQ
ENABLE=VDD
MIN
MAX
UNITS
VDD=3.3V
-
3.5
µA
VDD=5.5V
VDD=3.3V
VDD=5.5V
-
6.0
µA
-
35
µA
-
38
µA
IQBATOFF
VBAT < VBATCO,
VOUT=0
-
0.5
nA
IQBATON
VBAT > VBATCO,
IOUT=0
-
42
nA
INTERFACE LOGIC SIGNAL CHARACTERISTICS
VDD = 2.5V to 5.5V, Ta = -20ºC to +70ºC
CHARACTERISTIC
SYMBOL
CONDITION
MIN
High Level Input Voltage
Low Level Input Voltage
VIH
VIL
-
High Level Output Voltage
VOH
IL=10µA
Low Level Output Voltage
VOL
Logic Input Leakage Current
IIN
(1)
MAX
UNITS
VDD - 0.5
-
Volts
-
0.5
Volts
VDD 0.04V (1)
-
Volts
IL = -100µA
-
0.3
Volts
0<VIN<VDD
-1.0
+1.0
nA
RESET tracks VDD; RESET = VDD - (IOUT x ROUT).
RESET SIGNAL AC/DC CHARACTERISTICS
VDD = 2.5V to 5.5V, Ta = -20ºC to +70ºC
CHARACTERISTIC
VDD Rising to RESET
Rising
VDD Falling to RESET
Falling
TRIP Voltage
VDD Rising
RESET Hysteresis
Voltage
(VDD to RESET)
SYMBOL
CONDITION
MIN
MAX
UNITS
tRESETH
VDD rising from 2.8V TO 3.1V
in <10µs
60
200
ms
tRESETL
VDD falling from 3.1V to 2.8V
in <100ns
0.2
60
µs
VRESET
VMODE=GND
2.85
3.15
V
VHYST
VMODE=GND
45
75
mV
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Preliminary
CBC34803 EnerChip™ RTC
CHARGE PUMP CHARACTERISTICS (PERTAINS TO INTEGRATED CBC910 POWER MANAGEMENT CIRCUIT)
VDD = 2.5V to 5.5V, Ta = -20ºC to +70ºC
CHARACTERISTIC
ENABLE=VDD to Charge
Pump Active
ENABLE Falling to
Charge Pump Inactive
SYMBOL
tCPON
CONDITION
MIN
MAX
UNITS
60
80
µs
0
1
µs
-
120
KHz (1)
150
300
Ω
ENABLE to 3rd charge pump
pulse, VDD=3.3V
tCPOFF
-
Charge Pump Frequency
fCP
Charge Pump
Resistance
RCP
Delta VBAT, for IBAT charging
current of 1µA to 100µA
CFLY=0.1µF, CBAT=1.0µF
VCHG Output Voltage
VCP
CFLY=0.1µF, CBAT=1.0µF,
IOUT=1µA, Temp=+25ºC
4.065
4.150
V
VCHG Temp. Coefficient
TCCP
ICP
IOUT=1µA, Temp=+25ºC
-2.0
-2.4
mV/ºC
IBAT=1mA
CFLY=0.1µF, CBAT=1.0µF
1.0
-
mA
ENABLE=VDD
2.5
-
V
Charge Pump Current
Drive
Charge Pump on Voltage
(1)
VENABLE
fCP = 1/tCPPER
ADDITIONAL CHARACTERISTICS
Ta = -20ºC to +70ºC
CHARACTERISTIC
SYMBOL
CONDITION
VBAT Cutoff Threshold
Cutoff Temp. Coefficient
VBATCO
TCCO
IOUT=1µA
VBAT Cutoff Delay Time
tCOOFF
VBAT from 40mV above to
20mV below VBATCO
IOUT=1µA
LIMITS
UNITS
MIN
MAX
2.75
3.25
V
+1
+2
mV/ºC
18
-
ms
-
Note: All specifications contained within this document are subject to change without notice
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Preliminary
CBC34803 EnerChip™ RTC
Important Reference Documents for Design Information
• For complete specifications of the integrated Ambiq Micro AM0803 Real-Time Clock, see here:
http://www.cymbet.com/products/enerchip-real-time-clocks.php
• For complete specifications of the Cymbet 5µAh EnerChip and integrated power management circuit, see
this datasheet: http://www.cymbet.com/pdfs/DS-72-41.pdf .
• For an understanding of the tradeoffs in power consumption and timing accuracy when selecting a crystal
oscillator, see Application Note AN-1058 at http://www.cymbet.com/pdfs/AN-1058.pdf .
Functional Description of Integrated AM0803 Real-Time Clock
The AM0803 serves as a full function RTC for host processors such as microcontrollers. The AM0803 includes 3
distinct feature groups: 1) baseline timekeeping features with 32.768 kHz oscillator and 2) advanced
timekeeping features, and 3) basic power management features. Functions from each feature group may be
controlled via memory mapped registers. These registers are accessed using either an I2C serial interface (e.g.,
in the AM0803) or a SPI serial interface (e.g., in the AM0813). For more information on the AM0803, see here:
http://www.cymbet.com/pdfs/AM08XX_Data_Sheet_DS0002V1p0.pdf.
Low Power Operation
Minimum power operation will be achieved by turning off the CBC34803 charge pump in the power management
circuit by driving ENABLE (pin 15) low once the internal EnerChip has been charged - typically one hour to full
charge at room temperature.
The RTC has 3 low power modes, allowing the designer to make appropriate tradeoffs between power
consumption and timing accuracy. Operating current drawn by the internal RTC is as follows:
~15 nA with RC oscillator (+/- 1% timing accuracy)
~22 nA with RC oscillator and autocalibration (3-35ppm timing accuracy depending on run time)
~58 nA with crystal oscillator (+/- 2ppm timing accuracy after calibration at 25 °C)
In addition to the RTC current, the internal power management circuit typically draws 20-25nA from the EnerChip
storage device at room temperature.
The following table provides typical run times of the CBC34803 in backup mode over temperature.
Table 1: CBC34803 Backup Run Times at various RTC Modes and Temperatures
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Preliminary
CBC34803 EnerChip™ RTC
CBC34803 Register Definitions (0x00 to 0x0F)
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CBC34803 EnerChip™ RTC
CBC34803 Register Definitions (0x10 to 0xFF)
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CBC34803 EnerChip™ RTC
Registers With Special Programming Considerations
The following registers have special operations that require programmer attention when using the CBC34803
parts. Listed below are these registers by category of issue:
Key Register Access Values
The following registers require a write to the Configuration Key register of a specific value to allow a one-time
access. The Configuration Key register is automatically reset after the register is written:
Oscillator Control [0x1C] -> Write Configuration Key register to A1 hex (0xA1) prior to access
Trickle [0x20] -> Write Configuration Key register to 9D hex (0x9D) prior to access
BREF Control [0x21] -> Write Configuration Key register to 9D hex (0x9D) prior to access
AFCTRL [0x26] -> Write Configuration Key register to 9D hex (0x9D) prior to access
BATMODE I/O [0x27] -> Write Configuration Key register to 9D hex (0x9D) prior to access
OCTRL [0x30] -> Write Configuration Key register to 9D hex (0x9D) prior to access
Timing Register Holdoff During Read or Write
Reading any of the following registers in an autoincrement address or burst mode must finish the burst
in 10 milliseconds to avoid losing time. This is because the timing chain freezes until the burst is done to
avoid nonsensical time reads and can only assure correct time if you finish the entire register burst in 10
milliseconds. Reading the timing registers (Hundredths ->Years) takes about 100 clocks so a 10KHz bus clock
should be able to read the registers in the required 10mS if you don’t delay between reads.
These registers are Hundredths, Seconds, Minutes, Hours (24 Hour), Hours (12 Hour), Date, Months and Years.
Status Register
The Status register [0x0F] was listed as read-only in earlier documentation but all bits can be read or written
unless the ARST bit of the Control 1 [0x10] register is set which will cause a reset of interrupt bits (TIM, BL,
ALM, WDT, XT1, XT2) on any Status read.
Relationships Between Control1 Register and Oscillator Control Register
The Stop bit in the Control1 [0x10] register invalidates the OMODE bit in the Oscillator Status [0x1D] register.
The LKO2 bit in the Oscillator Status register locks out the R/W functionality of the OUTB bit of the Control1
register.
THE FOLLOWING REGISTER BIT SETTINGS ARE IMPORTANT FOR PROPER OPERATION
OSC.Control [0x1C, bit 4]: The default value of AOS out of reset is 0. THIS MUST TO BE REPROGRAMMED TO
1. To enable low power RC Oscillator to RUN while in the backup power state to increase run time.
BREF [0x21, bits 7:4]: The default value of BREF out of reset is 1111. Do not change the contents of this
register. This sets the VDD-to-backup battery switchover voltage threshold.
BATMODE I/O [0x27, bit 7]: The default value of IOBM out of reset is 1. THIS MUST TO BE REPROGRAMMED
TO 0. Setting this bit to 0 disables the bus interface in the backup power state to reduce currents through the
bus I/Os.
Cal_XT [0x14], Cal_RC_Hi [0x15], and Cal_RC_Low [0x16]: must be programed with values that provide
the desired clock accuracy. A description of the calibration process follows in this datasheet. Also refer to
Applications Note AN-1058 for register value administration details.
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CBC34803 EnerChip™ RTC
Crystal Oscillator Selection
The CBC34803 should work with any standard 32.768kHz tuning fork crystal with a load capacitance rating
from 0 - 12.5pF and an ESR from 0 – 90kohms. Recommendations are as follows:
•
•
•
•
Crystal load capacitance rating: 0 - 12.5pF
Crystal ESR rating: 0 – 90kohms max
No additional loading capacitors on the board
Stray PCB capacitance on XO/XI: 2pF or less (less is better)
Typically, an oscillator allowance (OA) of 260-290kohms is generated. Increasing the loading capacitance on
the XI/XO pins will decrease the OA and using crystals with a higher ESR will reduce the OA margin. The crystal
will not affect the internal RTC current because a fixed bias current to the crystal is used. No external load
capacitance is required because the frequency offset from the crystal is digitally calibrated out, to within +/2ppm. Mainstream crystals (3.2mm x 1.5mm) generally have a maximum ESR rating of 70kohms. The smaller
2.0mm x 1.2mm crystals generally have a maximum ESR of 90kohms. Some crystal vendors, such as Epson
or Micro Crystal, might have some of the smaller crystals with lower ESR. Below is a list of crystals from several
vendors that have been tested:
Abracon: ABS07-32.768KHZ-7-T, ABS06-32.768KHZ-9-T, ABS25.32.768KHZ-T
Epson: FC-135, FC-12D, FC-12M
Micro Crystal: CC7V-T1A, CM7V-T1A
Required Calibration of Crystal Oscillator Frequency for Proper System Operation
The CBC34803 uses an ultra-low power Real Time Clock chip that differs slightly in operation from legacy
higher power real time clocks. The following instructions must be implemented for proper operation.
In order to reduce power to the lowest level possible, the input load capacitance on the XO and XI pins on the
CBC34803 device has been purposely designed to be as low as possible and still retain good stability and
startup characteristics. Consequently the crystal oscillator frequency on CBC34803 parts will tend to run
100-300ppm higher in frequency than the nominal value of 32.768KHz when used with a 5 to 12pF crystal.
In order to compensate for this higher frequency, the CBC348o3 device has a set of calibration registers into
which the frequency offset in ppm is written. The clock divider chain then adds or subtracts pulses based
on the value in the calibration registers to insure that the nominal divided clock frequencies are now at
submultiples of 32.768Khz.
When calibrating the CBC34803, the fundamental crystal frequency is not changed, only the frequencies that
are below the fundamental frequency are modified by writing the ppm offset coefficients into the calibration
registers. This can be verified by setting the FOUT function to be a square wave and then measuring the various
undivided clock output vs. the divided clock after calibration. Please refer to the Ambiq Micro datasheet for the
calibration procedure.
Depending on the desired frequency tolerance for the application, one of two approaches can be used for
calibration:
1. For those applications where it is cost prohibitive to calibrate each unit, a generic calibration offset
can be used. The resulting frequency deviation will then match the crystal tolerance. Typically during
system qualification testing, several units will be tested and an average of all the fundamental oscillator
frequencies will be used to calculate the ppm offset coefficient to be written into the calibration registers.
2. For those applications requiring high precision, each unit can be measured and calibrated before shipping.
This approach will yield a system with a minimum of 2ppm frequency tolerance.
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CBC34803 EnerChip™ RTC
Initial Timing Calibration Algorithm
To initially calibrate out any crystal frequency inaccuracies and any parasitic load inaccuracies, the following
procedure should be run using a timing measurement device that can resolve better than one ppm in less
than a half-second. This device could be a frequency counter with a good calibration, a custom circuit built on
the device-under-test (DUT) board of the system tester that includes an accurate oscillator of 10MHz or better
and a counter that can count how many tenths of microseconds between the edges of the clock output from
the CBC34803, or possibly the system tester itself if it can be calibrated to resolve tenths of microseconds
between edges of the output clock. The procedure is as follows:
1. Set the OFFSETX, CMDX, and XTCAL register fields to 0 to make sure the oscillator is running without any calibration taking place. The CMDX and OFFSETX fields are both in the CAL_XT register. The
XTCAL bits are in the Osc Control register.
2. Select the XT oscillator by setting the OSEL bit of the Osc register to 0.
3. Configure a square wave output on one of the output pins of frequency Fnom (for example 16Hz). See
register SQW in the datasheet for information on how to do this.
4. Measure the pulse width of several cycles of the square wave with a resolution of better than 0.25ppm
(resolve edges to 15ns or better using averaging if needed) and convert to a frequency Fmeas by taking the
reciprocal of the pulse width.
5. Compute the pulse adjustment value (PADJ) required in ppm as:
((32,768 - Fmeas)*1000000) / 32,768 = PADJ.
6. Compute the adjustment value in steps as PADJ / (1000000 / 2^19) = Padj / (1.90735) = ADJ.
7. If ADJ < -320 the XT frequency is too high to be calibrated. Contact Cymbet for design assistance.
8. Compensate by starting at the top of this table and proceeding down until the pertinent condition is met and set the fields XTCAL, CMDX, and OFFSETX as indicated:
If ADJ is as below
set XTCAL =
set CMDX = set OFFSETX =
ADJ < -25631(ADJ + 192)/2
-256 < ADJ < -192
3
0
(ADJ + 192)
-192 < ADJ < -128
2
0
(ADJ + 128)
-128 < ADJ < -64
1
0
(ADJ + 64)
-64 < ADJ < 64
0
0
(ADJ)
64 < ADJ < 12801(ADJ)/2
Otherwise, XT is too low to calibrate. Contact Cymbet.
The calibration register values can be saved in nonvolatile memory in the final system’s microprocessor for
reloading when system power is recovered.
Timing Calibration Settings Calculator
Cymbet has created a Timing Calibration Settings Calculator for the CBC34803. This Excel spreadsheet can be
found here: http://www.cymbet.com/pdfs/Spreadsheet-to-set-EnerChip-RTC-348x3-values.xls.
To measure the timing error that might need correction, test your system with the CBC34803 over a period of
time and measure any clock drift. Once testing is complete, enter the Measured Error to Correct (seconds) and
the time duration of the test (seconds, hours, days, weeks) in the yellow indicated fields. If the ADJ range is
valid (green) , the Calculator will then compute the values for the following registers: OFFSETX, CMDX, XTCAL
and OSEL.
Additional information on crystal oscillator use can be found in this Application Note:
AN- 1058 Using CBC348xx EnerChip RTC in High Accuracy Applications
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CBC34803 EnerChip™ RTC
Typical CBC34803 EnerChip RTC Connection to Microcontroller
Figure 5 illustrates how the CBC34803 is typically connected to a microcontroller (MCU) in a system. For
simplicity, only the MCU lines routed to/from the CBC34803 are shown. The I/O line from the MCU to the EN pin
of the CBC34803 is optional for reducing power consumption of the CBC34803. The EN pin can be forced low by
the MCU when the integrated EnerChip does not need to be charged. If EN is not connected to the MCU or
otherwise controlled externally, it must be tied to VDD to ensure the EnerChip is charged when VDD is valid.
VDD
C1
VDD
0.1uF
OSCI
INT
2
3
SDA
VSS SCL
4
13
14
FOUT/IRQ
VOUT
AF
CBC34803
IRQ2
SCL
nc
nc
VSS VCHG VEC
SDA
8
MCU
I/O
OSCO
7
VDD
R3
10K
EN RESET VDD
5
U2
1
15
U1
6
VDD
R1
10K
32.768KHz
16
Y1
VDD
12
FOUT
11
10
C3
9
47pF
VDD
R2
10K
Figure 5: Typical Application Schematic Showing MCU Connections to CBC34803
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Preliminary
CBC34803 EnerChip™ RTC
GUIDELINES FOR HANDLING ENERCHIP RTC DEVICES
The EnerChip™ RTC with an integrated thin film, solid state battery features all solid state construction, are
packaged in standard integrated circuit packages, and can be reflow soldered for high volume PCB assembly.
The CBC34803 EnerChip RTC is considered an MSL-3 rated device for storage and handling purposes.
Device Handling & Storage
• EnerChip RTCs are packaged and shipped in tubes or reels 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 EnerChip RTCs 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 EnerChip RTCs 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)
• The EnerChip RTCs are sensitive to ESD damage prior to receiving a battery charge cycle. Therefore,
adherence to ESD prevention guidelines is required.
• Remove RTC 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.
Other Use Guidelines
• Do not connect the EnerChip RTC to other types of batteries.
• To increase battery life, avoid placing the EnerChip RTC near devices that would generate heat
exceeding the 70°C operating limit.
DO NOT HAND SOLDER ENERCHIP RTC DEVICES
When soldering an individual uncharged EnerChip RTC, a QFN capable soldering station with temperature control should be used. It is very important to be able to control the solder temperature and time when soldering
an EnerChip RTC.
ENERCHIP ASSEMBLY REPAIR TECHNIQUES
For the EnerChip RTC QFN package, 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.
©2014-2015 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
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Preliminary
CBC34803 EnerChip™ RTC
SMT PROCESS
The EnerChip RTCs 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 RTC on the PCB.
REFLOW SOLDERING
• The maximum number of times an uncharged EnerChip RTC may be reflow soldered is three times.
• The surface temperature of the EnerChip RTC package must not exceed 240°C.
• The recommended solder reflow profile is shown in Figure 6 below; refer to the table for time and
temperature requirements. Whenever possible, use lower temperature solder reflow profiles.
TP
TL
Parameter
Sn/Pb
Pb-free
Soak temperature, min, TSMIN
100°C
150°C
Soak temperature, max, TSMAX
Soak time, max, tS
Max ramp-up rate (TL to TP)
Liquidous temperature, TL
150°C
2 min
3°C/sec
183°C
200°C
2 min
3°C/sec
217°C
60-150 sec
60-150 sec
220°C
240°C
20 sec
6°C/sec
6 min max
30 sec
6°C/sec
8 min max
Time tL maintained above TL
Max peak temperature, TP
Max time tP at peak temperature TP Max ramp-down rate (TP to TL)
Time 25°C to peak temperature
Figure 6: EnerChip RTC Solder Reflow Profile and Specification Table
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Preliminary
CBC34803 EnerChip™ RTC
GUIDELINES FOR IN-CIRCUIT TESTING OF THE INTERNAL ENERCHIP BATTERY
It is very important to 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.
Precautions and Important Processes
After assembly on a printed circuit board, the CBC34803 integrated solid state battery is in an uncharged
state. It is important that the CBC34803 battery remain untested and uncharged until the last step of an incircuit system test so that if other components fail test and need to be replaced, the CBC34803 will still be in a
reflow-solderable state. The crystal and RTC in the CBC34803 can be tested independently from the battery at
the same time the other system elements are being tested.
There are two considerations when doing post-assembly testing of the user’s circuit board:
1.
When performing circuit testing, short the internal EnerChip battery to GND by forcing the VCHG/VEC pins
to ground potential during testing of the EnerChip RTC and other circuit functions. This will prevent the
integrated EnerChip from accumulating charge while the CBC34803 VDD and EN pins are active.
2. When the overall circuit testing is complete, it is permissible to verify connection to the EnerChip battery
and 4.1V output of the charge pump at the VCHG pin by forcing the CBC34803 VDD and EN pins high for
NO MORE THAN 3 SECONDS. Activating the charge pump for longer than 3 seconds will put sufficient
charge into the EnerChip that board level rework is no longer permitted without destroying the EnerChip.
Factory In-Circuit EnerChip Post Assembly Test Steps
CBC34803 In-Circuit Test Procedure
1. In order to keep the CBC34803 battery from charging during testing, apply GND using an in-circuit test bed
pin or other shorting method to the VCHG and VEC pins (6 and 7, respectively) that are normally tied together on the PCB. Alternatively, the EN pin on the CBC34803 can be forced to a logic low before performing board level testing as this will also prevent charge from accumulating in the battery. WARNING: If the
enable pin is asserted for more than 3 seconds with VDD ≥ 2.5 volts, the CBC34803 may not be reflowed
again.
2. Enable power domains under test, with VCHG/VEC net shorted to GND or EN forced to a logic low level.
3. Run all vectors to ensure proper functionality of all semiconductor devices.
4. After all other circuits are functional and boards have been reworked if needed.
5. Apply voltage to VIN that is in the range of 2.5V to 5.5V. (Note: VIN = VDD.)
6. Verify that the VCHG/VEC net is 4.1 volts +/- 0.025 volts.
7. Allow the battery to charge a very small amount by leaving the device in the above-noted configuration for
one second.
8. The chart in Figure 7 should be referenced to determine the voltage on the VCHG/VEC 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. Note: If not
using ATE with the ability to add a load impedance, it will be necessary to add resistance in parallel with
the voltage measurement device so the readings will match the graph of Figure 7. Any measurement
equipment and associated impedance circuits must only be temporally tied to the VCHG/VEC node for
the time needed to make the measurement (seconds) and no longer as the measurement impedance
will cause the battery to become discharged below 2.5V at which time the cell will become permanently
damaged.
9. The graph in Figure 7 depicts the time-dependent and temperature-dependent voltage of the EnerChip RTC
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.
©2014-2015 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
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Preliminary
CBC34803 EnerChip™ RTC
10. 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/VEC pin must be
above the value indicated by whichever line is chosen as the reference line.
11. Data at two temperatures is shown in order to encompass the range of 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
3.0
Charge-Discharge Time (seconds)
Figure 7: Voltage Determination on the VCHG/VEC Pin
CBC34803 Internal Battery Backup Verification: Optional Board/System Level Test. (1)
Warning: Board level reflow/rework is not permitted if the following procedure is used.
The following test is normally used in the prototype testing phase as this test may take 10-15 minutes to
perform which is typically unsuitable for high speed in-circuit testing.
1.
2.
3.
4.
5.
6.
7.
8.
Power up board or system.
Ensure that CBC34803 EN pin 15 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 operation.
Verify device contents.
Notes:
(1)
This test does not verify the actual capacity of the integrated battery. In order to verify actual capacity, the
device must be charged for at least one hour and then provide RTC power holdover until battery cut-off occurs.
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Preliminary
CBC34803 EnerChip™ RTC
CBC34803 Packaging
EnerChip CBC34803 devices are packaging in tubes or reels. The following specifications are for the 1000
and 5000 part reel packaging configurations.
CBC34803-Q5C-TR1 is a 7 inch reel with 1000 parts. Cymbet uses the Advantek LOKREEL Mini RJ7xx
packaging reel that has an outside diameter of 7 inches (180mm) and 1/2 inch (13mm) diameter arbor hole.
Reel hubs measure 2.36 inches (60mm). The 7 inch reel is compliant with EIAJ standards for dimension and
surface resistivity.
CBC34803-Q5C-TR5 is a 13 inch reel with 5000 parts. Cymbet uses the Advantek 13” LOKREEL packaging
reel that has an outside diameter of 13 inches (330mm) and 1/2 inch (13mm) diameter arbor hole. Reel
hubs measure 4 inches (102mm). The 13 inch reel is compliant with EIAJ standards for dimension and surface
resistivity.
Cymbet Part
Package
Type, # of
Devices
Reel Size
Outside
Diameter - A
Tape Width W, W1
Cavity Pitch P1
Meters per
Reel
Pockets/
Reel
Width
A0
Length
B0
Depth
K0
CBC34803-M5C-TR1
QFN, 1000
180mm
16mm, 8 mm
108
7000
5.45
5.45
1.8
CBC34803-M5C-TR5
QFN, 5000
330mm
16mm, 8mm
540
13000
5.45
5.45
1.8
Feed Direction
•
•
•
CBC34803 Pin1 Location Top side up
•
Ordering Information
EnerChip RTC Part Number
CBC34803-M5C-TR1
CBC34803-M5C-TR5
Description
EnerChip RTC in 5mm x 5mm x
1.4mm 16-QFN Land Grid Array
EnerChip RTC in 5mm x 5mm x
1.4mm 16-QFN Land Grid Array
CBC-EVAL-12-34803
EnerChip RTC Evaluation Kit
CBC34803-M5C
Notes
Shipped in Tube
Tape-and-Reel - 1000 pcs (TR1) or
5000 pcs (TR5) per reel
USB based Eval Kit with
CBC34803 tab board
U.S. Patent No. 8,144,508. Additional U.S. and Foreign Patents Pending
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.
Cymbet, the Cymbet Logo, and EnerChip are Cymbet Corporation Trademarks
©2014-2015 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-34 V.20
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