Product
Folder
Sample &
Buy
Support &
Community
Tools &
Software
Technical
Documents
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
bq500212A Low System Cost, Wireless Power Controller for WPC TX A5 or A11
1 Features
3 Description
•
The bq500212A is a Qi-certified value solution that
integrates all functions required to control wireless
power delivery to a single WPC1.1 compliant
receiver. It is WPC1.1 compliant and designed for 5-V
systems as a wireless power consortium type A5 or
A11 transmitter. The bq500212A pings the
surrounding environment for WPC compliant devices
to be powered, safely engages the device, receives
packet communication from the powered device and
manages the power transfer according to WPC1.1
specification. To maximize flexibility in wireless power
control applications, Dynamic Power Limiting (DPL) is
featured on the bq500212A. Dynamic Power Limiting
enhances user experience by seamlessly optimizing
the usage of power available from limited input
supplies.
Proven, Qi-Certified Value Solution for TransmitSide Application
Lowest Device Count for Full WPC1.1 5-V
Solution
5-V Operation Conforms to Wireless Power
Consortium (WPC1.1) Type A5 or A11 Transmitter
Specification
Fully WPC Compliant, Including Improved Foreign
Object Detection (FOD) Method
Permits X7R Type Resonant Capacitors for
Reduced Cost
Dynamic Power Limiting™ for USB and Limited
Source Operation
Digital Demodulation Reduces Components
LED Indication of Charging State and Fault Status
Low Standby and High Efficiency
1
•
•
•
•
•
•
•
•
2 Applications
•
Wireless Power Consortium (WPC1.1) Compliant
Wireless Chargers for:
– Qi-Certified Smart Phones and Other
Handhelds
– Car and Other Vehicle Accessories
See www.ti.com/wirelesspower for more
information on TI's Wireless Charging Solutions
•
The bq500212A supports both foreign object
detection (FOD) and enhanced parasitic metal object
detection (PMOD) for legacy product by continuously
monitoring the efficiency of the established power
transfer, protecting from power loss due to metal
objects misplaced in the wireless power transfer field.
The bq500212A handles any abnormal condition
development during power transfer and provides
indicator outputs. Comprehensive status and fault
monitoring features enable a low cost yet robust, Qicertified wireless power system design.
The bq500212A is available in a 48-pin, 7‑mm ×
7‑mm VQFN package.
Device Information(1)
PART NUMBER
PACKAGE
bq500212A
BODY SIZE (NOM)
VQFN (48)
7.00 mm × 7.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
System Diagram
Efficiency vs System Output Power
Current
Sense
5V
VIN
100%
90%
LDO
80%
PWM
½ Bridge
Driver
Tank /Coil
Assembly
½ Bridge
Driver
Communication
Copyright © 2016, Texas Instruments Incorporated
70%
Efficiency ( )
LED
bq500212 A
Wireless
Power Controller
60%
50%
40%
30%
20%
10%
0
0
1
2
3
Power (W)
4
5
D002
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
5
6.1
6.2
6.3
6.4
6.5
6.6
5
5
5
5
6
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 8
7.1
7.2
7.3
7.4
Overview ................................................................... 8
Functional Block Diagram ......................................... 8
Feature Description................................................... 9
Device Functional Modes........................................ 12
7.5 Programming........................................................... 14
8
Application and Implementation ........................ 15
8.1 Application Information............................................ 15
8.2 Typical Application .................................................. 15
9 Power Supply Recommendations...................... 18
10 Layout................................................................... 18
10.1 Layout Guidelines ................................................. 18
10.2 Layout Example .................................................... 19
11 Device and Documentation Support ................. 21
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Device Support......................................................
Documentation Support ........................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
21
21
21
21
21
21
21
12 Mechanical, Packaging, and Orderable
Information ........................................................... 21
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (January 2014) to Revision D
Page
•
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section ................................................................................................. 1
•
Deleted Ordering Information table; see POA at the end of the data sheet........................................................................... 1
Changes from Revision B (November 2013) to Revision C
•
Changed bq50012A Schematic to bq50012A Block Diagram.............................................................................................. 15
Changes from Revision A (August 2013) to Revision B
•
2
Page
Changed WPC1 to WPC1.1 throughout the document. ......................................................................................................... 1
Changes from Original (July) to Revision A
•
Page
Page
Changed marketing status from Product Preview to Production Data. .................................................................................. 1
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
5 Pin Configuration and Functions
ADCREF
GND
V_SENSE
RESERVED
LED_MODE
LOSS_THR
I_SENSE
RESERVED
COMM_B±
COMM_B+
COMM_A±
COMM_A+
48
47
46
45
44
43
42
41
40
39
38
37
D Package
8-Pin SOIC
Top View
PEAK_DET
1
36
GND
T_SENSE
2
35
BPCAP
SNOOZE_CAP
3
34
V33A
NC
4
33
V33D
RESET
5
32
GND
SLEEP
6
31
GND
LED_A
7
30
RESERVED
LED_B
8
29
RESERVED
SNOOZE
9
28
RESERVED
CLK
10
27
RESERVED
DATA
11
26
RESERVED
PWM_A
12
25
RESERVED
13
14
15
16
17
18
19
20
21
22
23
24
PWM_B
RESERVED
FOD_CAL
PMOD
FOD
LED_C
RESERVED
RESERVED
DOUT_TX
SNOOZE_CHG
BUZ_AC
BUZ_DC
Thermal Pad
Not to scale
Pin Functions
PIN
NAME
NO.
TYPE
DESCRIPTION
ADCREF
48
I
BPCAP
35
—
External reference voltage input. Connect this input to GND.
Bypass capacitor for internal 1.8-V core regulator. Connect bypass capacitor to GND.
BUZ_AC
23
O
AC buzzer output. Outputs a 400-ms, 4-kHz AC pulse when charging begins.
BUZ_DC
24
O
DC buzzer output. Outputs a 400-ms DC pulse when charging begins. This could also be
connected to an LED through 470-Ω resistor.
CLK
10
I/O
10-kΩ pullup resistor to 3.3-V supply. For factory use only.
COMM_A–
38
I
Digital demodulation inverting input A, connect parallel to input B–.
COMM_A+
37
I
Digital demodulation non-inverting input A, connect parallel to input B+.
COMM_B–
40
I
Digital demodulation inverting input B, connect parallel to input A–.
COMM_B+
39
I
Digital demodulation non-inverting input B, connect parallel to input A+.
DATA
11
I/O
DOUT_TX
21
I
10-kΩ pullup resistor to 3.3-V supply. For factory use only.
Not used. Leave this pin open.
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
3
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
Pin Functions (continued)
PIN
TYPE
DESCRIPTION
NAME
NO.
EPAD
Thermal
Pad
—
Flood with copper GND plane and stitch vias to PCB internal GND plane.
FOD
17
O
Set the threshold used to detect an FOD condition by connecting, through resistor, to LOSS_THR.
Leave open to disable FOD.
FOD_CAL
15
O
FOD calibration pin. It controls the FOD calibration setting at start-up.
31
I/O
Reserved, connect to GND.
32, 36, 47
—
Ground
I_SENSE
42
I
Transmitter input current, used for efficiency calculations. Use 20-mΩ sense resistor and a 50-gain
current sense amplifier.
LED_A
7
O
Connect to an LED through 470-Ω resistor for status indication.
LED_B
8
O
Connect to an LED through 470-Ω resistor for status indication.
LED_C
18
O
Connect to an LED through 470-Ω resistor for status indication.
LED_MODE
44
I
Input to select from four LED modes.
LOSS_THR
43
I
Input to program FOD and PMOD thresholds and FOD_CAL correction.
NC
4
—
PEAK_DET
1
I
Connected to peak detect circuit. Protects from coil overvoltage event.
PMOD
16
O
Set the threshold used to detect a PMOD condition by connecting, through resistor, to
LOSS_THR. Leave open to disable PMOD.
PWM_A
12
O
PWM output A, controls one half of the full bridge in a phase-shifted full bridge. Switching
deadtimes must be externally generated.
PWM_B
13
O
PWM output B, controls other half of the full bridge in a phase-shifted full bridge. Switching
deadtimes must be externally generated.
14, 19, 41
O
Reserved, leave this pin open.
GND
RESERVED
Not used. Can be left open. Can also be tied to GND and flooded with copper to improve GND
plane.
25, 26
I/O
Not used, leave this pin open.
27, 28, 29,
30
I/O
Reserved, leave this pin open.
20
I
Reserved, connect to GND.
45
I
Connect to V33D (3.3 V).
RESET
5
I
Device reset. Use a 10-kΩ to 100-kΩ pullup resistor to the 3.3-V supply.
SLEEP
6
O
Connected to 5 s interval circuit.
SNOOZE
9
O
Connected to 500 ms ping interval circuit.
SNOOZE_CAP
3
I
Connected to interval timing capacitor.
SNOOZE_CHG
22
I
Connected to interval timing capacitor.
T_SENSE
2
I
Sensor Input. Device shuts down when below 1 V for longer than 150 ms. If not used, keep above
1 V by connecting to the 3.3-V supply.
V33A
34
—
Analog 3.3-V Supply. This pin can be derived from V33D supply, decouple with 10-Ω resistor and
additional bypass capacitors.
V33D
33
—
Digital core 3.3-V supply. Be sure to decouple with bypass capacitors as close to the part as
possible.
V_SENSE
46
I
4
Transmitter input voltage, used for efficiency calculations. Use 76.8-kΩ to 10-kΩ divider to
minimize quiescent current.
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
Voltage applied at V33D to GND
–0.3
3.6
Voltage applied at V33A to GND
–0.3
3.6
–0.3
3.6
–40
150
Voltage applied to any pin
(2)
Storage temperature, Tstg
(1)
(2)
UNIT
V
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltages referenced to GND.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±750
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
V
Supply voltage during operation
TA
Operating free-air temperature
TJ
Junction temperature
V33D, V33A
MIN
NOM
MAX
3
3.3
3.6
V
110
°C
110
°C
–40
UNIT
6.4 Thermal Information
bq500212A
THERMAL METRIC (1)
RGZ (VQFN)
UNIT
48 PINS
RθJA
Junction-to-ambient thermal resistance
28.4
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
14.2
°C/W
RθJB
Junction-to-board thermal resistance
5.4
°C/W
ψJT
Junction-to-top characterization parameter
0.2
°C/W
ψJB
Junction-to-board characterization parameter
5.3
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
1.4
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
5
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
6.5 Electrical Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
V33A = 3.3 V
8
15
V33D = 3.3 V
44
55
V33D = V33A = 3.3 V
52
60
3.3
3.6
4
4.6
UNIT
SUPPLY CURRENT
IV33A
IV33D
Supply current
ITOTAL
mA
INTERNAL REGULATOR CONTROLLER INPUTS AND OUTPUTS
V33
3.3-V linear regulator
V33FB
3.3-V linear regulator feedback
IV33FB
Series pass base drive
Beta
Series NPN pass device
Emitter of NPN transistor
3.25
VIN = 12 V; current into V33FB pin
10
V
mA
40
EXTERNALLY SUPPLIED 3.3 V POWER
V33D
Digital 3.3-V power
TA = 25°C
3
3.6
V33A
Analog 3.3-V power
TA = 25°C
3
3.6
V33Slew
V33 slew rate
V33 slew rate between 2.3 V to 2.9 V,
V33A = V33D
0.25
V
V/ms
DIGITAL DEMODULATION INPUTS COMM_A+, COMM_A–, COMM_B+, COMM_B–
Vbias
COMM+ bias voltage
COMM+,
COMM–
1.5
Modulation voltage digital resolution
REA
Input impedance
Ground reference
0.5
IOFFSET
Input offset current
1-kΩ source impedance
–5
V
1
1.5
mV
3
MΩ
5
µA
0.36
V
ANALOG INPUTS V_SENSE, I_SENSE, T_SENSE, LED_MODE, LOSS_THR, SNOOZE_CAP, PWR_UP
VADDR_OPEN
Voltage indicating open pin
LED_MODE open
VADDR_SHORT
Voltage indicating pin shorted to GND
LED_MODE shorted to ground
VADC_RANGE
Measurement range for voltage monitoring
All analog inputs
INL
ADC integral nonlinearity
RIN
Input impedance
CIN
Input capacitance
Ground reference
2.37
0
2.5
–2.5
2.5
8
mV
MΩ
10
pF
DIGITAL INPUTS/OUTPUTS
VOL
Low-level output voltage
IOL = 6 mA, V33D = 3 V
VOH
High-level output voltage
IOH = –6 mA, V33D = 3 V
DGND1 + 0.25
VIH
High-level input voltage
V33D = 3 V
VIL
Low-level input voltage
V33D = 3.5 V
IOH(MAX)
Output high source current
4
IOL(MAX)
Output low sink current
4
V33D – 0.6 V
2.1
3.6
V
1.4
mA
SYSTEM PERFORMANCE
VRESET
Voltage where device comes out of reset
V33D pin
tRESET
Pulse width needed for reset
RESET pin
ƒSW
Switching Frequency
6
2.4
2
112
Submit Documentation Feedback
V
µs
205
kHz
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
6.6 Typical Characteristics
Figure 1. Typical PWM-A and PWM-B Signals
Figure 2. Typical Start-Up With RX
Figure 3. Typical Shutdown EPT01
Figure 4. Typical Comm RX to TX
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
7
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
7 Detailed Description
7.1 Overview
The principle of wireless power transfer is simply an open-cored transformer consisting of transmitter and
receiver coils. The transmitter coil and electronics are typically built into a charger pad, and the receiver coil and
electronics are typically built into a portable device such as a cell phone. When the receiver coil is positioned on
the transmitter coil, magnetic coupling can occur when the transmitter coil is driven. The flux is coupled into the
secondary coil, inducing a voltage, causing current to flow. The secondary voltage is rectified, allowing power to
be transferred effectively to a load wirelessly. Power transfer can be managed through any of the various closedloop control schemes.
7.2 Functional Block Diagram
bq500212A
LED Control /
Low Power
Interface
COMM_A+ 37
COMM_A- 38
SLEEP
7
LED_A
8
LED_B
9
SNOOZE
15 FOD_CAL
18 LED_C
Digital
Demodulation
COMM_B+ 39
6
16 PMOD
17 FOD
COMM_B- 40
12 PWM-A
Controller
PWM
13 PWM-B
PEAK_DET
1
V_SENSE 46
I_SENSE 42
T_SENSE
2
12-bit
ADC
23 BUZ_AC
Buzzer
Control
24 BUZ_DC
LOSS_THR 43
LED_MODE 44
SNOOZE_CAP
POR
11 DATA
I2C
3
10 CLK
5
RESET
8
Submit Documentation Feedback
Copyright © 2016, Texas Instruments Incorporated
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
7.3 Feature Description
7.3.1 Principles of Operation
7.3.1.1 Fundamentals
The principle of wireless power transfer is simply an open-cored transformer consisting of primary and secondary
coils and associated electronics. The primary coil and electronics are also referred to as the transmitter, and the
secondary side the receiver. The transmitter coil and electronics are typically built into a charger pad. The
receiver coil and electronics are typically built into a portable device, such as a cell phone.
When the receiver coil is positioned on the transmitter coil, magnetic coupling occurs when the transmitter coil is
driven. The flux is coupled into the secondary coil which induces a voltage, current flows, it is rectified and power
can be transferred quite effectively to a load wirelessly. Power transfer can be managed through any of various
familiar closed-loop control schemes.
7.3.1.2 Wireless Power Consortium (WPC)
The Wireless Power Consortium (WPC) is an international group of companies from diverse industries. The WPC
standard was developed to facilitate cross compatibility of compliant transmitters and receivers. The standard
defines the physical parameters and the communication protocol to be used in wireless power. For more
information, go to www.wirelesspowerconsortium.com.
7.3.1.3 Power Transfer
Power transfer depends on coil coupling. Coupling is dependant on the distance between coils, alignment, coil
dimensions, coil materials, number of turns, magnetic shielding, impedance matching, frequency, and duty cycle.
Most importantly, the receiver and transmitter coils must be aligned for best coupling and efficient power transfer.
The closer the space between the coils, the better the coupling, but the practical distance is set to be less than
5 mm (as defined within the WPC Specification) to account for housing and interface surfaces.
Shielding is added as a backing to both the transmitter and receiver coils to direct the magnetic field to the
coupled zone. Magnetic fields outside the coupled zone do not transfer power. Thus, shielding also serves to
contain the fields to avoid coupling to other adjacent system components.
Regulation can be achieved by controlling any one of the coil coupling parameters. For WPC compatibility, the
transmitter coils and capacitance are specified and the resonant frequency point is fixed at 100 kHz. Power
transfer is regulated by changing the operating frequency between 110 kHz to 205 kHz. The higher the
frequency, the further from resonance and the lower the power. Duty cycle remains constant at 50% throughout
the power band and is reduced only once 205 kHz is reached.
The WPC standard describes the dimension and materials of the coils. It also has information on tuning the coils
to resonance. The value of the inductor and resonant capacitor are critical to proper operation and system
efficiency.
7.3.1.4 Communication
Communication within the WPC is from the receiver to the transmitter, where the receiver tells the transmitter to
send power and how much. In order to regulate, the receiver must communicate with the transmitter whether to
increase or decrease frequency. The receiver monitors the rectifier output and using Amplitude Modulation (AM),
sends packets of information to the transmitter. A packet is comprised of a preamble, a header, the actual
message and a checksum, as defined by the WPC standard.
The receiver sends a packet by modulating an impedance network. This AM signal reflects back as a change in
the voltage amplitude on the transmitter coil. The signal is demodulated and decoded by the transmitter side
electronics and the frequency of its coil drive output is adjusted to close the regulation loop. The bq500212A
device features internal digital demodulation circuitry.
The modulated impedance network on the receiver can either be resistive or capacitive. Figure 5 shows the
resistive modulation approach, where a resistor is periodically added to the load and also shows the resulting
change in resonant curve which causes the amplitude change in the transmitter voltage indicated by the two
operating points at the same frequency. Figure 6 shows the capacitive modulation approach, where a capacitor
is periodically added to the load and also shows the resulting amplitude change in the transmitter voltage.
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
9
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
Feature Description (continued)
Rectifier
Receiver Coil
Receiver
Capacitor
Amax
Modulation
Resitor
Operating state at logic “0”
A(0)
Operating state at logic “1”
A(1)
Comm
Fsw
a)
F, kHz
b)
Figure 5. Receiver Resistive Modulation Circuit
Rectifier
Receiver Coil
Receiver
Capacitor
Modulation
Capacitors
Amax
Comm
A(0)
Operating state at logic “ 0”
A(1)
Operating state at logic “ 1”
Fsw
F, kHz
Fo(1) < Fo(0)
a)
b)
Figure 6. Receiver Capacitive Modulation Circuit
7.3.2 Dynamic Power Limiting
Dynamic Power Limiting (DPL) allows operation from a 5-V supply with limited current capability (such as a USB
port). When the input voltage is observed drooping, the output power is dynamically limited to reduce the load
and provides margin relative to the supply's capability.
Anytime the DPL control loop is regulating the operating point of the transmitter, the LED indicates that DPL is
active. The LED color and flashing pattern are determined by the Table 2. If the receiver sends a Control Error
Packet (CEP) with a negative value, (for example, to reduce power to the load), the WPTX in DPL mode
responds to this CEP through the normal WPC control loop.
NOTE
The power limit indication depends on the LED_MODE selected.
10
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
Feature Description (continued)
7.3.3 Shut Down Through External Thermal Sensor or Trigger
Typical applications of the bq500212A device do not require additional thermal protection. This shutdown feature
is provided for enhanced applications and is not only limited to thermal shutdown. The key parameter is the 1-V
threshold on T_SENSE pin. Voltage below 1 V on T_SENSE pin for longer than 150 ms causes the device to
shutdown.
The application of thermal monitoring through a Negative Temperature Coefficient (NTC) sensor, for example, is
straightforward. The NTC forms the lower leg of a temperature dependant voltage divider. The NTC leads are
connected to the bq500212A device, T_SENSE pin and GND. The threshold on T_SENSE pin is set to 1 V,
below which the system shuts down and a fault is indicated (depending on LED mode chosen).
To
1.
2.
3.
4.
implement this feature follow these steps:
Consult the NTC data sheet and find the resistence vs temperature curve.
Determine the actual temperature where the NTC is placed by using a thermal probe.
Read the NTC resistance at that temperature in the NTC data sheet, that is R_NTC.
Use Equation 1 to determine the upper leg resistor (R_Setpoint):
R _ Setpoint = 2.3 ´ R _ NTC
(1)
The system restores normal operation after approximately five minutes or if the receiver is removed. If the feature
is not used, this pin must be pulled high.
NOTE
T_SENSE pin must always be terminated; otherwise, erratic behavior may result.
3V3_VCC
Optional
Temperature
Sensor
R_Setpoint
T_SENSE
NTC
2
AGND
AGND
Figure 7. Negative Temperature Coefficient (NTC) Application
7.3.4 Fault Handling and Indication
Table 1 provides approximate durations for the time before a retry is attempted for end power transfer (EPT)
packets and fault events. Precise timing may be affected by external components, or shortened by receiver
removal. The LED mode selected determines how the LED indicates the condition or fault.
Table 1. Fault Handling
CONDITION
DURATION
(BEFORE RETRY)
EPT-00
Immediate
Unknown
EPT-01
5s
Charge complete
HANDLING
EPT-02
Infinite
Internal fault
EPT-03
5 minutes
Over temperature
EPT-04
Immediate
Over voltage
EPT-05
Immediate
Over current
EPT-06
Infinite
Battery failure
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
11
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
Table 1. Fault Handling (continued)
CONDITION
DURATION
(BEFORE RETRY)
HANDLING
EPT-07
Not applicable
Reconfiguration
EPT-08
Immediate
No response
OC (over current)
1 minute
NTC (external sensor)
5 minutes
PMOD/FOD warning
12 s
PMOD/FOD
5 minutes
10 s LED only,
2 s LED + buzzer
7.3.5 Power Transfer Start Signal
The bq500212A device features two signal outputs to indicate that power transfer has begun. BUZ_AC pin
outputs a 400-ms duration, 4-kHz square wave for driving low-cost, AC-type ceramic buzzers. BUZ_DC pin
outputs logic high, also for 400 ms, which is suitable for DC type buzzers with built-in tone generators, or as a
trigger for any type of customized indication scheme. If not used, these pins can be left open.
7.3.6 Power On Reset
The bq500212A device has an integrated Power On Reset (POR) circuit which monitors the supply voltage and
handles the correct device start-up sequence. Additional supply voltage supervisor or reset circuits are not
needed.
7.3.7 External Reset, RESET Pin
The bq500212A device can be forced into a reset state by an external circuit connected to the RESET pin. A
logic low voltage on this pin holds the device in reset. For normal operation, this pin is pulled up to 3.3 VCC with a
10-kΩ pullup resistor.
7.3.8 Trickle Charge and CS100
The WPC specification provides an End-of-Power Transfer message (EPT-01) to indicate charge complete. Upon
receipt of the charge complete message, the bq500212A device changes the LED indication. The exact
indication depends on the LED_MODE chosen.
In some battery charging applications there is a benefit to continue the charging process in trickle-charge mode
to top off the battery. There are several information packets in the WPC specification related to the levels of
battery charge (Charge Status). The bq500212A device uses these commands to enable top-off charging. The
bq500212A device changes the LED indication to reflect charge complete when a Charge Status message is
100% received, but unlike the response to an EPT, it does not halt power transfer while the LED is solid green.
The mobile device can use a CS100 packet to enable trickle charge mode.
If the reported charge status drops below 90% normal, charging indication is resumed.
7.4 Device Functional Modes
7.4.1 LED Indication Modes
The bq500212A device can directly drive up to three LED outputs (LED_A, LED_B, and LED_C) through a
simple current limit resistor (typically 470 Ω), based on the mode selected. The current limit resistors can be
individually adjusted to tune or match the brightness of the LEDs. Do not exceed the maximum output current
rating of the device. The resistor in Figure 8 connected to LED_MODE and GND selects the desired LED
indication scheme in Table 2.
• LED modes permit the use of one to three indicator LED's. Amber in the 2-LED mode is obtained by turning
on both the green and red.
• LEDs can be turned on solid or configured to blink either slow (approximately 1.6 s period) or fast
(approximately 400 ms period).
• Except in modes 2 and 9, the charge complete state is only maintained for 5 seconds after which it reverts to
idle. This permits the processor to sleep in order to reduce standby power consumption. In other modes,
external logic, such as a flip-flop, may be implemented to maintain the charge complete indication if desired.
12
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
Device Functional Modes (continued)
Table 2. LED Modes
LED
CONTROL
OPTION
LED
SELECTION
RESISTOR
OPERATIONAL STATES
STANDBY
POWER
TRANSFER
CHARGE
COMPLETE
FAULT
DYNAMIC
POWER
LIMITING
FOD Warning
—
—
—
—
—
—
LED1, green
Off
Blink slow
On
Off
Blink slow
Off
LED2, red
Off
Off
Off
On
Blink slow
Blink fast
DESCRIPTION
LED
LED1, green
X
< 36.5 kΩ
Reserved,
do not use
LED2, red
LED3, amber
1
2
3
4
5
6
7
8
9
10
42.2 kΩ
48.7 kΩ
56.2 kΩ
64.9 kΩ
75 kΩ
86.6 kΩ
100 kΩ
115 kΩ
133 kΩ
154 kΩ
Choice number 1
Choice number 2
Choice number 3
Choice number 4
Choice number 5
Choice number 6
Choice number 7
Choice number 8
Choice number 9
Choice number 10
LED3, amber
—
—
—
—
—
—
LED1, green
On
Blink slow
On
Off
Blink slow
Off
Blink fast
LED2, red
On
Off
Off
On
Blink slow
LED3, amber
—
—
—
—
—
—
LED1, green
Off
On
Off
Blink fast
On
On
—
LED2, red
—
—
—
—
—
LED3, amber
—
—
—
—
—
—
LED1, green
Off
On
Off
Off
Off
Off
LED2, red
Off
Off
Off
On
Blink slow
Blink fast
LED3, amber
—
—
—
—
—
—
LED1, green
Off
Off
On
Off
Off
Off
LED2, red
Off
On
Off
Off
On
On
LED3, amber
Off
Off
Off
Blink slow
Off
Off
LED1, green
Off
Blink slow
On
Off
Off
Off
LED2, red
Off
Off
Off
On
Off
Blink fast
LED3, amber
Off
Off
Off
Off
Blink Slow
Off
LED1, green
Off
Blink slow
Off
Off
Off
Off
LED2, red
Off
Off
On
Off
Off
Off
LED3, amber
Off
Off
Off
On
Blink slow
Blink fast
LED1, green
Off
Off
On
Blink slow
Off
Off
LED2, red
Off
On
Off
Blink slow
On
On
LED3, amber
—
—
—
—
—
—
LED1, green
Off
Blink slow
On
Off
Blink slow
Off
Blink fast
LED2, red
Off
Off
Off
On
Blink slow
LED3, amber
—
—
—
—
—
—
LED1, green
Off
On
Off
Blink fast
Blink slow
On
LED2, red
Off
Off
On
Off
Off
Off
LED3, amber
—
—
—
—
—
—
7.4.2 Low Power Mode
During standby, when nothing is on the transmitter pad, the bq500212A device pings the surrounding
environment at fixed intervals. The ping interval can be adjusted; the component values selected for the
SNOOZE circuit determine this interval between pings. The choice of the ping interval effects two quantities: the
idle efficiency of the system, and the time required to detect the presence of a receiver when it is placed on the
pad. A trade-off must be made which balances low power (longest ping interval) with good user experience
(quick detection through short ping interval) while still meeting the WPC requirement for detection within
0.5 seconds.
The system power consumption is approximately 300 mW during an active ping, which lasts approximately
90 ms, and 40 mW for the balance of the cycle. A weighted average can thus be used to estimate the overall
system's idle consumption:
If T_ping is the interval between pings in ms, P_idle in mW is calculated with Equation 2.
P_idle (mW) = (40 × (T_ping – 90) + 300 × 90) / T_ping
(2)
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
13
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
7.5 Programming
7.5.1 Option Select Pins
Several pins on the bq500212A device are allocated to programming the FOD and PMOD Loss Threshold and
the LED mode of the device. At power up, a bias current is applied to pins LED_MODE and LOSS_THR and the
resulting voltage measured in order to identify the value of the attached programming resistor. The values of the
operating parameters set by these pins are determined using Table 4. For LED_MODE, the selected bin
determines the LED behavior based on Table 2; for the LOSS_THR, the selected bin sets a threshold used for
PMOD (see PMOD, FOD, and FOD Calibration). See Table 2.
bq500212A
LED_MODE
44
Resistors
to set
options
LOSS_THR
To 12-bit ADC
43
FOD
PMOD
FOD_CAL
17
16
15
UDG-13119
Figure 8. Option Select Pin Programming
7.5.2 Current Monitoring Requirements
The bq500212A device is WPC1.1 ready. To enable the FOD or PMOD features, current monitoring circuitry
must be provided in the application design.
For proper scaling of the current monitor signal, the current sense resistor must be 20 mΩ and the current shunt
amplifier must have a gain of 50, such as the INA199A1. For FOD accuracy, the current sense resistor must be a
quality component with 1% tolerance, at least 1/4-W rating, and a temperature stability of ±200 PPM. Proper
current sensing techniques in the application hardware must also be observed.
If WPC compliance is not required current monitoring can be omitted. Connect the I_SENSE pin to GND.
7.5.3 All Unused Pins
All unused pins can be left open unless otherwise indicated. The NC pin can be tied to GND and flooded with
copper to improve ground shielding. See Pin Configuration and Functions for further more information.
14
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The bq500212A device is a wireless power transmitter controller designed for 5-W WPC compliant applications.
The device has has all features required to support receivers that are compliant with WPC 1.0, 1.1, and Low
Power 1.2. Additional tools and application information can be found in the bq500212A product folder. The
following section highlight some of the system design considerations.
8.2 Typical Application
Figure 9 shows the application schematic for the transmitted with reduced standby power.
NOTE
Check the bq500212A product page for the most up-to-date application schematic and list
of materials package before starting a new design.
5V
VIN
5V
VIN
3.3 V
LDO
Current
Sense
bq500212A
Wireless
Power Controller
Snooze
CLK
Coil
A5/A11
Power
Section
Sleep
CLK
COMM
CKT
Copyright © 2016, Texas Instruments Incorporated
Figure 9. bq50012A Block Diagram
8.2.1 Design Requirements
For this design example, use the parameters listed in Table 3 as the input parameters.
Table 3. Design Parameters
PARAMETER
EXAMPLE VALUE
WPC coil type
A11 and A5
Input voltage
5 V ±5% (5-V input to A11 / A5 TX)
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
15
bq500212A
SLUSBD6D – JULY 2013 – REVISED JULY 2016
www.ti.com
8.2.2 Detailed Design Procedure
8.2.2.1 PMOD, FOD, and FOD Calibration
The bq500212A device supports improved FOD (WPC1.1) and enhanced PMOD (WPC 1.0) features.
Continuously monitoring input power, known losses, and the value of power reported by the RX device being
charged, the bq500212A device can estimate how much power is unaccounted for and presumed lost due to
metal objects placed in the wireless power transfer path. If this unexpected loss exceeds the threshold set by the
FOD or PMOD resistors, a fault is indicated and power transfer is halted. Whether the FOD or the PMOD
algorithm is used is determined by the ID packet of the receiver being charged.
As the default, both PMOD and FOD resistors must set a threshold of 400 mW (selected by 56.2-kΩ resistors
from FOD and PMOD to LOSS_THR. 400 mW has been empirically determined using standard WPC FOD test
objects (disc, ring, and foil). Some tuning might be required as every system is slightly different. This tuning is
best done by trial and error, use the set resistor values given in the table to increase or decrease the loss
threshold and retry the system with the standard test objects. The ultimate goal of the FOD feature is safety; to
protect misplaced metal objects from becoming hot. Reducing the loss threshold and making the system too
sensitive leads to false trips and a bad user experience. Find the balance which best suits the application.
If the application requires disabling one function or the other (or both), it is possible by leaving the respective
FOD pin and PMOD pin open. For example, to selectively disable the PMOD function, PMOD must be left open.
NOTE
Disabling FOD results in a TX solution that is not WPC compliant.
Resistors of 1% tolerance must be used for a reliable selection of the desired threshold.
The FOD and PMOD resistors program the permitted power loss for the FOD and PMOD algorithms respectively.
The FOD_CAL resistor, can be used to compensate for any load dependent effect on the power loss. Using a
calibrated test receiver with no foreign objects present, the FOD_CAL resistor must be selected such that the
calculated loss across the load range is substantially constant (within approximately 100 mW). After correcting
for the load dependence, the FOD and PMOD thresholds must be reset above the resulting average by
approximately 400 mW for the transmitter to satisfy the WPC requirements on tolerated heating. Contact TI for
more information about setting appropriate FOD, PMOD, and FOD_CAL resistor values for your design.
Table 4. Option Select Bins
16
BIN NUMBER
RESISTANCE (kΩ)
LOSS THRESHOLD
(mW)
0
237
Feature Disabled
Submit Documentation Feedback
Copyright © 2013–2016, Texas Instruments Incorporated
Product Folder Links: bq500212A
bq500212A
www.ti.com
SLUSBD6D – JULY 2013 – REVISED JULY 2016
8.2.2.2 Coils and Matching Capacitors
The coil and matching capacitor selection for the transmitter has been established by WPC standard. These
values are fixed and cannot be changed on the transmitter side.
An up to date list of available and compatible A5 or A11 transmitter coils can be found in bqTESLA Transmitter
Coil Vendors (SLUA649):
Capacitor selection is critical to proper system operation. A total capacitance value of 400 nF is required in the
resonant tank. A 400-nF capacitor is not a standard value and therefore several must be combined in parallel. TI
recommends to use 4 × 100 nF, as these are very commonly available.
NOTE
A total capacitance value of 400 nF/50 V is required in the resonant tank to achieve a 100kHz resonance frequency.
To achieve the 400-nF total capacitance in the resonant tank, the bq500212A device sensitive demodulation
circuitry allows the use of 3 lower cost 100-nF/X7R type capacitors in parallel with one (1) high quality 100nF/C0G type, thereby reducing system cost from competitive solutions requiring four C0G types.
The capacitors chosen must be rated for 50 V operation. Use quality capacitors from reputable vendors such as
KEMET, MURATA or TDK.
8.2.2.3 Design Checklist for WPC1.1 Compliance With the bq500212A
• Coil and capacitor selection matches the A5/A11 specification.
• Total 400-nF resonant capacitor requirement is composed of: (3 × 100nF/X7R) + (1 × 100nF/C0G) types.
• Precision current sense amp used, such as the INA199A1. This is required for accurate FOD operation.
• Current shunt resistor 1% and
工商网监
湘ICP备2023018690号
