Cymbet CBC915-ACA-TR1 Enerchipâ ¢ energy processor for energy harvesting application Datasheet

CBC915 EnerChip™ EP
Energy Processor
EnerChip™ Energy Processor for Energy Harvesting Applications
Features
•
Use any type of Energy Harvesting (EH)
transducer: Light, Vibration, Thermal, RF, etc.
Advanced Maximum Peak Power Tracking
Algorithms for High Efficiency Energy Conversion
EH Transducer to System Load Impedance
Matching
Communications Interface to System MCU
Energy Status Indicators for Incoming Energy
and Storage Energy Levels
Charge Control for EnerChip CBC050 Thin Film
Energy Storage Devices
Built-in Energy Storage Protection
Temperature Compensated Charge Control
Adjustable Switchover Voltage
Low Standby Power
38 pin TSSOP Package
-20°C to +70°C or - 40°C to 85°C Temperature
Operating Range
SMT - Lead-Free Reflow Tolerant
RoHS Compliant
•
•
•
•
•
•
•
•
•
•
•
•
•
Energizing Your Innovation
Many new energy harvesting based products can be
enabled by the EnerChip EP:
•
•
•
•
•
•
Various ambient energy sources can
be harvested to power new designs
using : Photo Voltaic Cells, Piezoelectric
vibration harvesters, Thermoelectric cells,
Electromagnetic harvesters, RF Induction
charging.
Designs can use ultra low power by leveraging
the Maximum Peak Power Tracking EnerChip
EP capabilities
The power management communications
interface to the system MCU can be used to
create “Energy Aware” systems
Input power measurement and status
reporting
Advanced energy storage management
Uses digital power controls
Everything is Inside the EnerChip EP
The EnerChip EP uses an advanced Maximum Peak
Power Tracking (MPPT) algorithm that constantly
matches the EH transducer output impedance. MPPT is
the most efficient method of converting energy from an
EH transducer and is superior to charge accumulation
techniques that do not match the impedance of
the transducer to the power conversion stage. The
EnerChip EP operates in multiple modes and can
communicate with microcontrollers. The EP manages
all aspects of energy storage devices/peripherals and
uses intelligent power management during the startup initialization sequence. The EP operates at 1/10
the power of other EH power management units.
Ideal for High Efficiency Wireless Sensors
The key to designing energy harvesting-based wireless
sensors with high efficiency power conversion is
to utilize the EnerChip EP along with EnerChip
rechargeable energy storage devices. The EnerChip EP
performs the high efficiency energy conversion, energy
storage and power management. It is the key enabler
of “Zero Power” systems as shown in the following
diagram:
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72- 15 Rev C
Page 1 of 16
CBC915 EnerChip Energy Processor
EnerChip EP Solves the Challenges of Energy Harvesting
There are many exciting new applications that could use Energy Harvesting for powering devices. Unfortunately,
utilizing the “free” ambient energy surrounding a system is a very complex design challenge, with many questions
to answer:
•
•
•
•
•
•
How to interface to energy harvesting transducers?
How to convert low input power with high efficiency?
How to manage energy storage?
How to control power to the rest of the system?
How to best manage the system power states?
How to make the entire system “Energy Aware”?
The EnerChip™ Energy Processor solves these challenges by implementing an intelligent integrated approach to
Energy Harvesting Power Management.
Maximum Peak Power Tracking is the Key to High Efficiency
In order to achieve maximum power transfer from an Energy Harvesting transducer, it is critical to match the
transducer impedance to the system load impedance. Therefore, Pmax is when RT=RL.
The EnerChip EP as the Energy Processing Stage serves to match the impedances of the transducer to the
power converter and decouples the system load from the energy conversion circuits while also controlling the
energy storage elements in the system.
Factory Test
DVDD
NC
DVSS
EC CHG
EN CAP CHG
RST
VGSENSE
MPPT
ECFB
CAPCHG
NC
NC
STATUS SW
AVSS
AVDD
NC
NC
NC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
EN VOUT
MODE SEL3
EN VCAP
CALIBRATE
LX
CUTOFF EN
MODE SEL2
ISOLATE EN
VCAP
MODE SEL1
MODE SEL0
CUTOFF RST
RXD
TXD
NC
NC
NC
NC
NC
EnerChip Energy Processor CBC915-ACA Pin Designations
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 2 of 16
CBC915 EnerChip Energy Processor
EnerChip Energy Processor CBC915 Pin Descriptions
Pin Number
Pin Designation
Description - (Input or Output)
1
Factory Test
Factory test pin - leave unconnected (I)
2
DVDD
Digital supply voltage (same as AVDD) (i)
3
NC
Not used - leave unconnected (NC)
4
DVSS
Digital ground reference (same as AVSS) (I)
5
EC CHG
EnerChip charge indicator, pin pulses low in response to STATUS SW/ (O)
6
EN CAP CHG
Enable Capacitor Charge goes low while charging the output capacitor (O)
7
RST
Tie this pin to DVDD through a 100kΩ resistor (I)
8
VGSENSE
Voltage generator input - range 0V to 2.5V (I)
9
MPPT
Maximum Peak Power Tracking indicator (O)
10
ECFB
EnerChip charge voltage feedback input (I)
11
CAP CHG
Capacitor Charge indicator; this pin pulses low in response to STATUS SW/ (O)
12
NC
Not used - leave unconnected
13
NC
Not used - leave unconnected
14
STATUS SW
Status state switch (see Status Indicators section) (I)
15
AVSS
Analog ground reference - tie to system ground (same as DVSS) (I)
16
AVDD
Analog supply voltage (same as DVDD) (I)
17
NC
Not used - leave unconnected
18
NC
Not used - leave unconnected
19
NC
Not used - leave unconnected
20
NC
Not used - leave unconnected
21
NC
Not used - leave unconnected
22
NC
Not used - leave unconnected
23
NC
Not used - leave unconnected
24
NC
Not used - leave unconnected
25
TXD
Serial I/O transmit data out of the Energy Processer Data rate is 9600 8N1 (O)
26
RXD
Serial I/O receive data into the Energy Processer Data rate is 9600 8N1 (I)
27
CUTOFF RST
A high level will cause the EnerChip to disconnect from the system load (O)
28
MODE SEL0
Used in conjunction with MODE SEL1 to select transducer type (I)
29
MODE SEL1
Used in conjunction with MODE SEL0 to select transducer type (I)
30
VCAP
Output capacitor feedback monitor (I)
31
ISOLATE EN
A high level will isolate all loads from the Energy Processer (0)
32
MODE SEL2
Not used - leave unconnected (future product enhancement) (NC)
33
CUTOFF EN
A high level will force the EnerChip to connect to the system load (O)
34
LX
Boost converter switch driver (O)
35
CALIBRATE
Only used in target system calibration (see Calibration Function section) (I)
36
EN VCAP
When high connects the VCAP A/D pin to the output capacitor (O)
37
MODE SEL3
Not used - leave unconnected (future product enhancement) (I)
38
EN VOUT
When low connects power to the application system (O)
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 3 of 16
CBC915 EnerChip Energy Processor
EnerChip Energy Processor CBC915 Operating and Maximum Parameters
Parameter
Min
Typ
Max
Unit
3.5
3.6
V
0
-
V
Recommended Operating Conditions
Supply voltage VDD
2.5
Supply voltage VSS
-
Operating temperature - CBC915-ACA
-20
+25
+70
°C
Operating temperature - CBC915-AIA
-40
+25
+85
°C
Voltage applied at VDD to VSS
-0.3
-
4.1
Voltage applied to any pin
Absolute Maximum Ratings
V
-0.3
-
VDD+0.3
V
Diode current at any device terminal
-2
-
-2
mA
Storage temperature range
-55
-
+105
°C
Notes:
1. Thermal or electrical stresses beyond those listed under absolute maximum ratings may cause permanent damage
to the CBC915. These are stress ratings only, and functional operation of the device at these or any other conditions
beyond those indicated under recommended operating conditions is not implied. Exposure to absolute maximum rated
conditions for extended periods my affect device reliability.
EnerChip Energy Processor CBC915 I/O Pin Characterization
Parameter
Conditions
VDD
Min
Typ
Max
Unit
Positive-going input threshold voltage
3.5
1.59
-
2.63
V
Negative-going input threshold
voltage
3.5
0.88
-
1.91
V
3.5
Input voltage hysteresis
0.36
-
-
V
Pullup/Pulldown resistor
for pullup, VIN=VSS
for pulldown, VIN=VDD
20
35
50
kΩ
Input Capacitance
VIN=VSS or VDD
-
5
-
pF
High impedance leakage current
See notes 1 and 2
-
-
3.5
+/- 50
nA
VOH - High level output voltage
100uA
3.5
VDD-0.25 -
VDD-0.1
V
VOL - Low level output voltage
100uA
3.5
VSS
-
VSS+0.1
V
25 °C
0 to 80 °C
N/A
-
+/- 1%
+/- 2.5%
Internal clock frequency tolerance
-
MHz
Notes:
1. The leakage current is measured with VDD or VSS applied to the corresponding pin(s) unless otherwise noted.
2. The leakage of the I/O pins is measured individually. The I/O pin is selected for input and the pullup/pulldown resistor
is disabled. All inputs except STATUS SW/ and CALIBRATE/ are high impedance inputs.
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 4 of 16
CBC915 EnerChip Energy Processor
CBC915 Operation
The CBC915 performs the function of efficiently converting energy from an external power transducer to a voltage
and current usable by typical applications such as remote wireless sensors. The CBC915 performs this function
by dynamically matching its input impedance to the output impedance of the transducer. At impedance match,
maximum power will be extracted from the transducer.
Differences Among Power Transducers
There are many different types of power transducers used in energy harvesting applications; they are broadly
divided into two categories. Photovoltaic (PV) cells are unique and consequently in their own category due to
the diode-like current-voltage (IV) characteristics of PV cells. The PV cell impedance changes with changes in
incident light intensity. As the light intensity increases, the PV cell impedance decreases. For example, typical
impedance for a 30cm2 two-series amorphous silicon cell array will be 1kΩ at 1000Lux and 5kΩ at 200Lux.
Therefore, transferring maximum power from the PV cell into CBC915 Energy Processor boost converter requires
the input impedance of the boost converter to change dynamically in response to light intensity (thus PV cell
impedance) fluctuations. Plotting a load line of current vs. voltage on a graph will show a diode-like response
curve, in contrast to a purely resistive source which having a linear load line response. When presented with
a matched impedance, the output voltage of an efficient PV cell is fairly constant over varying incident light
intensity. In contrast, the voltage at the peak power point of a less efficient voltage will change with variations
in light intensity. The CBC915 adjusts its input impedance to match the output characteristics of any type or
quality of PV cell. The CBC915 was designed to work with PV cells arrays of 1-series to 8-series cells, equating to
approximately 0.5V to 4V at matched impedance. In most cases it is most power efficient to use a PV array with
two cells in series. Series-cell configurations with fewer cells have the advantage of not losing as much efficiency
due to shading and have more efficiency per unit area because there are fewer gaps in the array that do not
contribute to energy conversion.
The power curve of Figure 1 is typical of a low power PV cell used in energy harvesting applications. Electrical
impedance of the cell varies strongly as a function of ambient light. As illustrated, the power curve is highly nonlinear, meaning that connecting an electrical load to the PV cell that is not matched to its impedance results in
inefficient power transfer to that load.
Normalized Power From a Photovoltaic Cell
100
5490
90
4880
80
4270
70
3660
60
3050
50
2440
40
1830
30
1220
20
610
10
0
Voltage as a percentage of open circuit voltage
Power (I x V)
6100
Power
Volts
0
0
10
20
30
40
50
60
70
80
90
100
Current as a percentage of short circuit current
Figure 1. Maximum Peak Power Point for Variable Resistance Transducer
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 5 of 16
CBC915 EnerChip Energy Processor
Most other energy harvesting transducers (e.g., thermoelectric and piezoelectric generators) have constant
output impedance. These constant impedance transducers can be further categorized into subgroups based on
impedance and typical output voltage.
Most - but not all - thermoelectric generators (TEGs) have low impedances (less than 300Ω) and output voltages
that vary linearly with the temperature difference across the generator. The matched impedance output voltage
of a TEG used in an energy harvesting application is typically in the low tens of millivolts to around 1V depending
on the number of elements in the TEG and temperature difference across the TEG. The CBC915 energy processer
is designed to work with TEGs with several hundred ohms of impedance and open circuit output voltages ranging
from 500mV to 2V. Extracting maximum efficiency from a TEG requires careful mechanical design which allows
good thermal conduction from the hot to cold side of the TEG but at the same time insulates any thermal leakage
path around the TEG that can reduce the temperature differential. Piezoelectric generators also have a constant
impedance characteristic, in that changes in input excitation cause a fairly linear change in output voltage.
Piezoelectric generators typically have output impedances in the 10kΩ to 100kΩ range, with output voltage
that changes linearly with input excitation. Most piezoelectric energy harvesters elements resonate at only one
particular frequency with a power bandwidth of only a few Hertz (2-3Hz being typical). The CBC915 Energy
Processer is designed to work with piezoelectric generators having an output voltage - after rectification and
filtering into a matched load - ranging from 4.5V to 20V DC.
The current-voltage (I-V) profile depicted in Figure 2 is indicative of a constant impedance transducer. From the
I-V curve, it is evident that operation at a point away from the peak power point results in a significant reduction
of power available from the transducer and therefore to the load. Consequently, to transfer a useful amount
of power to the load when input power is scarce, it is imperative to match the impedance of the transducer;
moreover efficient power conversion using impedance matching must be done dynamically, as the transducer I-V
profile will often vary in accordance with fluctuations in ambient conditions.
2500
100
2250
90
2000
80
1750
70
1500
60
1250
50
1000
40
750
30
500
20
250
10
0
Voltage as a percentage of open circuit voltage
Power (I x V)
Normalized Power From a Constant Impedance Transducer
Power
Volts
0
0
10
20
30
40
50
60
70
80
90
100
Current as a percentage of short circuit current
Figure 2. Current-Voltage Profile of a Constant Impedance Transducer
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 6 of 16
CBC915 EnerChip Energy Processor
Electromagnetic generators used for typical energy harvesting applications have an output impedance of several
hundred ohms to several thousand ohms with an impedance of approximately 1kΩ being typical. The output
voltage of an electromagnetic generator will change linearly with input excitation. In most applications, voltages
in the range of 500mV to 2V DC after rectification and filtering are typical.
CBC915 operation with a thermoelectric generator (TEG) transducer (as shown in Figure 3) starts with a
temperature differential across the TEG. This temperature differential causes the TEG to generate a voltage.
When that voltage reaches approximately 400mV, the input charge pump will start, boost the input voltage, and
store the accumulated charge in capacitor Cin. When the accumulated charge voltage reaches approximately
2.4V, the charge will be dumped into the CBC915 power rail, activating the CBC915. Upon activation, the CBC915
outputs are initialized to a known state and the input mode pins will be interrogated in order to recognize the
transducer type. The CBC915 will then pulse-width modulate the LX pin and initiate operation of the boost
converter. When the boost converter voltage rises above 2.4V, power to the input charge pump is removed to
reduce quiescent current. The CBC915 then checks for voltage on the output capacitor (Cout) by setting the EN
VCAP pin high and reading the output capacitor voltage on VCAP pin. If the capacitor is charged, the CBC915 will
leave the capacitor connected to the VOUT pin and EnerChips. If the capacitor has not been charged, the CBC915
will turn off the VOUT connection by setting EN VOUT/ pin high and isolate the capacitor from the EnerChips by
setting EN CAP CHG/ pin high. The CBC915 will then check the boost converter voltage by monitoring the voltage
at the VOUT pin and wait for the voltage to reach 4.06V at which time the CBC915 will enter the maximum peak
power tracking state (MPPT) and pulse the MPPT/ status pin low and start adjusting the boost converter input
impedance to match the output impedance of the TEG. This process can take several minutes. The MPPT state
is only entered at initial power-on and values are subsequently stored. Note the MPPT state can be entered by
five different events:
•
•
•
•
•
at initial power up;
when powered up while the Status/ input is held low
by command over the serial interface;
by detection of the input voltage being at a lower level than what it was at the initial MPPT startup while
VOUT is not in regulation (voltage to low);
when the input voltage is at a higher level and VOUT is not in regulation (voltage too high).
Figure 3. CBC915 Energy Processor Application Circuit
In all cases while in the MPPT state, the boost converter is isolated from the EnerChip(s), output capacitor,
and load. During MPPT mode, the load will be operating from the energy stored in the output capacitor and
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 7 of 16
CBC915 EnerChip Energy Processor
EnerChip(s). Once the maximum peak power point is found, the CBC915 will then set the ISOLATE EN line high
to connect the boost converter to the power management circuits, then repeatedly pulse the CAP CHG pin low.
The periodic pulsing of EN CAP CHG/ pin low enables small amounts of charge energy to be transferred from
the boost converter to the output capacitor with each low pulse on the EN CAP CHG/ pin. While the output
capacitor is being charged, the CBC915 will monitor the output capacitor voltage on the VCAP pin. When the
output capacitor voltage rises to 2V, the CBC915 will stop pulsing and set the EN CAP CHG/ pin low continuously;
this state allows maximum energy to be transferred from the boost converter into the output capacitor. When
the output capacitor voltage reaches 3.4V, the CBC915 will set the EN VOUT/ line low, connecting the output
capacitor to the application system load. At the same time, the CBC915 will pulse the EC CHG/ line low and pulse
the CUTOFF RST line high, thereby connecting the EnerChip to the boost converter, output capacitor, and applying
power to the application system load. The CBC915 then monitors the output of the boost converter; when the
boost converter is in regulation the CBC915 will simultaneously pulse low the EC CHG/, CAP CHG/, and MPPT/
pins. This state indicates the output is turned on and the system is in regulation, which typically happens once
the EnerChips have nearly a full charge.
Status Input Pin
This pin is internally pulled high. Tie this pin to a switch or open drain/collector output to pull low. When pulled low
STATUS SW/ will cause the EC CHG LED/, MPPT LED/, and CAP CHG/ pins to pulse low depending on the state
of the Energy Processor. When in the normal state, with power applied to the system and in regulation with fully
charged EnerChips, all the lines will pulse low simultaneously. If the STATUS SW/ pin is held low for more than 10
seconds while the system is in regulation, EN VOUT/ will go high, shutting off power to the application system.
Subsequent pulses of less than 10 seconds will cause the EN CAP CHG/ and MPPT/ pins to pulse low and the
EN VOUT/ line to remain in the high (power disconnected) state. Holding STATUS SW/ line low for greater than 10
seconds will restore the Energy Processor to its normal state, with EN VOUT/ in the low state, power applied to the
application system, and all three status lines pulsing low in response to a low level pulse on STATUS SW/.
Calibration Function
The CBC915 features a calibration function to remove errors caused by unit to unit variation in the voltage
divider resistors (R1 and R2 of Figure 3) used to drive the ECFB input. The CALIBRATE/ pin has an internal pull
up resistor and can be driven by an open drain/collector output or switch contact. To calibrate apply 4.06V to the
V+ node. Then short the CALIBRATE/ pin to ground for approximately 100mS. The EC CHG LED/, MPPT LED/, and
CAP CHG/ pins will simultaneously pulse low when the CBC915 has stored its calibration values.
Operating Modes
•
•
•
•
Mode 0: Electromagnetic transducers; input voltage range 0.5V to 4V after rectification and filtering.
Mode 1: Thermoelectric generators; input voltage range 400mV for startup. 200mV to 1V at matched
impedance.
Mode 2: Piezoelectric generators; input voltage range 4V to 20V after rectification, loaded to matched
impedance.
Mode 3: Photovoltaic cells; 900mV to 4V at matched impedance.
MODE
MODE SEL3
MODE SEL2
MODE SEL1
MODE SEL0
0 (Electromagnetic)
X
X
0
0
1 (Thermoelectric)
X
X
0
1
2 (Piezoelectric)
X
X
1
0
3 (Photovoltaic)
X
X
1
1
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 8 of 16
CBC915 EnerChip Energy Processor
EnerChip EP Communications Interface and Commands
The CBC915 has seven serial I/O commands to enable the end application to be “energy aware”. The serial I/O
UART is configured as 9600 Bits per second, 8 bits, no parity bit, 1 stop bit. 9600 8N1.
The I/O lines are TXD and RXD, described as follows:
TXD - Serial I/O transmit data out of the Energy Processor. Data rate is 9600 8N1 (0)
RXD - Serial I/O receive data into the Energy Processor. Data rate is 9600 8N1 (1)
The serial I/O commands are:.
Command 1: Power Available. This command returns - in microwatts - the total power available from the energy
harvesting transducer. The application can use this information to change its performance characteristics
depending on the input power available. This command is typically used in conjunction with command 4 (Find
Maximum Peak Power Point)
Command 2: State of CBC915. This command returns the current state of the CBC915. The CBC915 is always in
one of five different states:
State 1: Maximum Peak Power Tracking (MPPT). In this mode, the CBC915 adjusts the impedance of the
power conversion stage to match the output impedance of the energy harvesting transducer. While in State
1, the load is not powered from the energy harvester.
State 2: Capacitor Charging. While in State 2, the CBC915 charges the output capacitor. This state is typically
entered only once at initialization or if the EnerChips were to become deeply discharged. While in State 2, the
output capacitor is isolated from the load until the output capacitor has reached full charge.
State 3: EnerChip Charging. This state is entered after the output capacitor charging state is completed and
the system is not in regulation. During State 3 power is applied to the load.
State 4: System in Regulation. This state is entered when the system is in regulation.
State 5 Output Off. This state would typically only be detected and used in a laboratory environment, as power
would normally be turned off to the load and thus prevent serial communications.
Command 3: Transducer Type. This command is typically used during production test to ensure the mode input
pins have been set to the correct value for the particular transducer being used.
Command 4: Find Maximum Peak Power Point. To conserve power, the CBC915 only finds the maximum peak
power point once at initialization or anytime the CBC915 falls out of regulation (voltage to high or low) while
at the same time detecting a change in input voltage. If it is desired to reset the maximum peak power point
the host microcontroller can force the CBC915 to find the maximum peak power point. While this command is
being executed power from the energy harvester is cut off to the application and the application system will
get its power while the CBC915 is finding the peak power point from the EnerChip(s) and output capacitor. This
command would typically only be used on systems using PV cells that change impedance with changes in light
level, other transducer types with constant impedance would typically derive little if any benefit from a reset of
the peak power point.
Command 5: EnerChip State of Charge. This command returns the state of charge as a percentage of total
capacity. This indicator is based on a voltage measurement and will not be totally accurate as the EnerChips age,
or with large deviations from room temperature.
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 9 of 16
CBC915 EnerChip Energy Processor
Command 6: Calibrate EnerChip EP. This command requires a 4.06V power supply to be connected to the
converter output. This command reads current A/D voltage and set as new A/D reading as 4.06 volts for the
output A/D converter. This command can also be implemented with hardware using the CALIBRATE/ input line.
Command 7: This command returns as a single string data from:
Command 1 (Power Available)
Command 2 (State of the CBC915)
Command 3 (Transducer Type)
Command 5 (EnerChip State of Charge)
EnerChip EP Serial Port Command and Response Syntax
The CBC915 supports a command/response protocol on the serial port. The syntax for the commands and
responses is listed as follows.
Characters not enclosed in <> are case-sensitive required ASCII characters. 0 = null (hex 0).
Do not insert extra whitespace characters.
<XX> is defined as an ASCII decimal number of exactly the same number of digits as shown between the < and
>. Leading zeros are used to left fill the field. (The < and > are not sent.)
<cr> is defined as an ASCII carriage return . (The < and > are not sent.)
<lf> is defined as an ASCII line feed. (The < and > is not sent.)
<space> is defined as an ASCII space character. (The < and > is not sent.)
Protocol Request Command to CBC915 on RXD line
<#> <space> <command number> <carriage return>
Protocol response from CBC915 on TXD line
<@> <command number> <comma> (data returned) <carriage return> <line feed> <zero>
All commands to the CBC915 take this form on the RXD line:
#<space> <X><cr>
Where X is the command number.
Example:
# 2<cr> requests the state of the CBC915
Protocol response from CBC915 on TXD line is as follows:
@<X>,<DDDD><cr><lf>>0
Where <X> is an ASCII decimal number echoing the command number and <DDDD> is a specific length (4 digits
in this case) ASCII decimal number. Notice the ASCII comma character between the command number and data
parameter and the ASCII zero following the <cr>
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 10 of 16
CBC915 EnerChip Energy Processor
Example:
@2,05<cr><lf>>0 is a response from command 2 that the CBC915 is in state 5.
Response 1: Power Available
<@> <command number> <comma> <XXXXX> <line feed> <carriage return> <zero>
XXXXX= ASCII numbers for microwatts of power (1-99999)
Example: Command request for power available #<sp>1<cr> ;where <sp> = ASCII space character and
<cr> = ASCII carriage return character
Command returns @1,00237<cr><lf>0 Where 00237 is 237uW of power available and <lf> is ASCII
line feed character
Response 2: State of CBC915
<@> <command number> <comma> <XX><carriage return> <line feed> <zero>
XX= ASCII numbers for State (1-99)
State 1 = MPPT mode
State 2 = Capacitor charging
State 3 = EnerChip(s) charging
State 4 = System in regulation
State 5 = Output off
Response 3: Transducer Type
<@> <command number> <comma> <XX> <carriage return> <line feed> <zero>
XX= ASCII numbers for transducer type (1-99)
Transducer 1 = Low voltage input; typically TEG
Transducer 2 = PV cell input
Transducer 3 = High voltage input; typically piezoelectric
Transducer 4 = Medium voltage input, constant impedance transducers; typically electromagnetic
generators
Response 4: Find Maximum Peak Power Point
<@> <command number> <comma> <ack> <carriage return><line feed> <zero>
<ack>= ASCII ACK
Response 5: EnerChip State of Charge
<@> <command number> <comma> <XXX><carriage return> <line feed> <zero>
XXX= ASCII numbers as percent of full charge (requires command to be requested twice for accurate
data)
Response 6: Calibrate EnerChip EP.
<@> <command number> <comma> <XXXX> <carriage return> <line feed> <zero>
XXXX= ASCII numbers for A/D reading for 4.06 volts
Response 7: Returns data from Command 1, Command 2, Command 3, and Command 5
<@> <command number> <comma> <XXXXXYYZZUUU> <carriage return><line feed> <zero>
X = ASCII numbers for POWER
Y = ASCII numbers for STATE
Z = ASCII numbers for TRANSDUCER TYPE
U = ASCII numbers for ENERCHIP percent charge
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 11 of 16
CBC915 EnerChip Energy Processor
Status Indicators
The following lines are used for the peak power tracking algorithm and must not be left unconnected:
•
•
•
EC CHG/ (EnerChip Charge) - indicates EnerChip charging state.
CAP CHG/ (Capacitor Charge) - indicates capacitor charging state.
MPPT/ (Maximum Peak Power Tracking) - indicates Maximum Peak Power Tracking (MPPT) state.
Each of the pins must be tied to a 1kΩ resistor pulled to the positive supply rail. Alternatively, the status indicator
pins may each be tied to an LED in series with a current limiting resistor pulled up to the 4.06V supply rail via a
diode, as shown in Figure 3. All three status lines must be connected to a load so the CBC915 has a way to bleed
off excess energy while in the MPPT state.
There is one status request pin and three status indicators.
Status Input Pin
STATUS SW/ is pulled high internally. Tie this pin to a switch or open drain/collector output to pull low. When
pulled low STATUS SW/ will cause the EC CHG/, MPPT/, and CAP CHG/ lines to pulse low depending on the
state of the Energy Processer. When in the normal state with power applied to the system and in regulation with
fully charged EnerChips, all the lines will pulse low simultaneously. If STATUS SW/ is held low for more then 10
seconds, EN VOUT/ will go high shutting off power to the application system, subsequent pulses of less then 10
seconds will cause the EN CAP CHG/ and MPPT lines to pulse low and the EN VOUT/ line to remain in the high
or power disconnected state. Holding STATUS SW/ line low for greater then 10 seconds will restore the Energy
Processor to its normal state with EN VOUT/ in the low state with power applied to the application system and all
three status lines pulsing low in response to a low level pulse on STATUS SW/.
When all three status indicators simultaneously pulse low, the output is connected to the load, the EnerChips
are charged, and the system is in regulation. The status indicator corresponding to each state will automatically
pulse low when the system enters that state. The EnerChip EP operating state can be requested by pulsing
STATUS SW/ low. This will cause the corresponding indicators to pulse low.
Activating a status indicator requires a momentary (less than one second) low pulse to STATUS SW/. The
associated indicator pin will then be driven low once.
Holding the STATUS SW/ pin low for approximately ten seconds will cause the CBC915 to disconnect from the
load. If the STATUS/ pin is then momentarily pulsed low, the EC CHG/ and CAP CHG/ indicator pins will pulse low,
indicating the batteries are charged, output is in regulation, and the load is disconnected.
Holding the STATUS SW/ pin again for approximately ten seconds will toggle the load back to being connected
to the energy harvester. The status indicators will pulse low. Any subsequent momentary push of the switch
will result in all three status indicators toggling once, provided the batteries are charged and the output is in
regulation. Holding the STATUS SW/ pin low unitl the CBC915 is powered up will force the CBC915 to enter the
MPPT state.
EnerChip Charge Indicator
EnerChip charge indicator (EC CHG/) pulses low in response to STATUS SW/ being pulsed low while the
EnerChip(s) is (are) being charged. EC CHG/ state is an indication that the output is connected to the energy
harvester and the output voltage is not in regulation. It is possible – under direct sunlight conditions or other high
power transducers for instance – for the system to be in regulation yet have EnerChips not fully charged. This
indicator will be the most accurate when used indoors under normal/lower lighting conditions or with a low power
transducer. This state can take from minutes to hours to complete depending on light intensity and/or energy
available. In this state the output is disconnected from the energy harvester.
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 12 of 16
CBC915 EnerChip Energy Processor
Capacitor Charge Indicator
Capacitor charge indicator (CAP CHG/). This pin pulses low in response to STATUS SW/ being pulsed low while
the output capacitor is being charged. The CAP CHG/ state occurs only on initialization, during the time the
output capacitors are being charged. This state can take minutes to hours to complete depending on the energy
available at the harvesting transducer input. In this state, the EN VOUT/ output pin is driven high.
MPPT Indicator
Maximum Peak Power Tracking indicator. This pin goes low in response to STATUS SW/ being pulsed low when
the Energy Processor is tracking the maximum peak power operating point. Engaging the MPPT state typically
takes about a minute and occurs only when the system is first initialized or when the system can no longer stay
in regulation and the input voltage has changed from the last time MPPT was completed. For example, if a light
source has changed position throughout the day and the load current remains low, no MPPT will occur. If the load
were to increase and light intensity increased or decreased, MPPT state will be entered to allow peak power to
flow to the load. Note: Anytime the MPPT state is entered, the load, if connected, will be deriving its power from
the EnerChips and not the photovoltaic cells.
EC CHG/, CAP CHG/, and MPPT/ pins must be connected to 1K ohm resistors or LEDs. The following table
describes the operational modes for the several possible combinations of these three pins. Refer to CBC-EVAL-09
data sheet for further clarification of mode descriptions. The file is located here: http://www.cymbet.com/pdfs/
DS-72-13.pdf
EC CHG/
PIN
CAP CHG/
MPPT/
HIGH
HIGH
PULSED LOW
Maximum peak power tracking
HIGH
PULSED LOW
HIGH
Output holding capacitor charging
PULSED LOW
HIGH
HIGH
EnerChip charging
PULSED LOW
PULSED LOW
PULSED LOW
Normal operation; system in regulation
HIGH
PULSED LOW
PULSED LOW
Output state change; driven low when STATUS SW/ is driven
low for 5 seconds
PULSED LOW
HIGH
PULSED LOW
Output to load turned off; same as EnerChip charging
PULSED LOW
PULSED LOW
HIGH
Output to load turned off; system in regulation
MODE DESCRIPTION
Important EnerChip EP Pin Connections
DVDD and AVDD should be connected together on the printed circuit board.
DVSS and AVSS should be connected together on the printed circuit board.
DVDD should be connected with bypass cap to DVSS - typical capacitance value is 0.1uF; place as close to pins
2 and 4 as possible and in parallel a 10uF cap for low frequency decoupling
AVDD should be connected with bypass cap to AVSS - typical capacitance value is 0.1uF; place as close to pins
2 and 4 as possible and in parallel with a 10uF cap for low frequency decoupling.
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 13 of 16
CBC915 EnerChip Energy Processor
Printed Circuit Board (PCB) Layout Guidelines for the CBC915 Application Circuit
The boost converter power stage consists of elements with tens of milliamperes of current along with control
electronics with very high impedances operating at only a few nanoamperes of current. This disparity between
current densities in the power stage vs. the control circuits can lead to poor circuit performance, poor efficiency
and excessive noise coupling into other circuits if careful layout practices are not observed.
As in most switch mode power supply layouts, it is usually advantageous to isolate the power stage from the
control electronics through a combination of isolated current conductors or by careful placement of power stage
components in such a manner that the high currents in the power stage stay in an area associated only with
the power stage components. Proper design and layout of the CBC915 application circuit will ensure maximum
circuit performance.
Power stage components Cin, L, Q, D1, D2, and Cout should all be in close physical proximity to each other.
When placing the components, it is better to make the traces associated with Cout the shorter path. The signal
return conduction path should either be at the edge or corner of the board if a common ground plane is used,
or routed together outside of the ground plane and then tied to the ground plane at a single point - preferably
at the signal return connection for Cout. All traces interconnecting the power components should be as short
and wide as practical; this will help eliminate parasitic inductance and conducted losses which will in turn
help keep conducted noise and magnetic fields out of adjacent circuits. Doing a good job with the power stage
component placement and layout will yield the best performance of the system as a whole. This area should not
be compromised if maximum performance is to be achieved.
The feedback resistors R1 and R2 should be as close as practical to the VGSENSE input on the CBC915. The
signal return line for resistor R2 should be isolated from the high current power stage signal return lines, either
by placement of the components relative to the power stage components or by providing separate return lines.
Place bypass capacitors as near to the CBC915 VDD and VSS pins as possible. If using a power and ground
plane, drop vias directly from the bypass capacitors to the power and ground planes and from the CBC915 VDD
and VSS pins directly to the power and ground planes.
In general, all discrete components should be placed physically close to the gate connection of the transistor they
are associated with. Keep the node lengths as short as possible to the FET gate connections.
Follow the PCB layout guidelines in the EnerChip data sheet and User Manual for details on how to minimize stray
leakage paths on EnerChip package pins and PCB routing traces.
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 14 of 16
CBC915 EnerChip Energy Processor
Package Outline (38-TSSOP)
All linear dimensions in mm. (Max/Min)
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 15 of 16
CBC915 EnerChip Energy Processor
Environmental and Transportation Standards Compliance
is not
applicable to
this product
Ordering Information
EnerChip Part Number
Description
Notes
CBC915-ACA
CBC915 EnerChip Energy
Processor
38-Pin TSSOP Package shipped in
tubes
CBC915-ACA-TR1
CBC915 EnerChip Energy
Processor
38-Pin TSSOP Package shipped as
1000 part tape and reel
CBC915-ACA-TR5
CBC915 EnerChip Energy
Processor
38-Pin TSSOP Package shipped as
5000 part tape and reel
CBC915-AIA
CBC915 EnerChip Energy
Processor - Industrial Temp
38-Pin TSSOP Package shipped in
tubes
CBC915-AIA-TR1
CBC915 EnerChip Energy
Processor - Industrial Temp
38-Pin TSSOP Package shipped as
1000 part tape and reel
CBC915-AIA-TR5
CBC915 EnerChip Energy
Processor - Industrial Temp
38-Pin TSSOP Package shipped as
5000 part tape and reel
CBC-EVAL-09
EnerChip EP Universal Energy
Harvesting Evaluation Kit
CBC915-ACA with EnerChip 51100
module and solar cell
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 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 products are not approved for use in life critical applications. Users shall confirm suitability
of the Cymbet battery product in any products or applications in which the Cymbet 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 product described
herein in any such product or applications.
Cymbet, the Cymbet Logo and EnerChip are trademarks of Cymbet Corporation. All Rights Reserved
EnerChip products and technology are covered by one or more patents or patents pending.
©2010-2011 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
DS-72-15 Rev C
Page 16 of 16
Similar pages