Texas Instruments bq51025EVM-649 User manual

User's Guide
SLUUB55–September 2014
bq51025 Evaluation Module (PWR649)
The bq51025EVM-649 (PWR649) wireless power receiver evaluation kit (EVM) from TI is a high
performance, easy-to-use development kit for the design of wireless power solutions. It helps designers
evaluate the operation and performance of the bq51025 IC, a secondary-side receiver device for wireless
power transfer applications. The bq51025 device is a fully-contained, wireless power receiver capable of
operating in WPC v1.1 protocol which allows a wireless power system to deliver up to 5 W to the system
when used with a Qi inductive transmitter. When paired with the bq500215EVM-648 (PWR648), the
bq51025 is capable of delivering up to 10 W to the system. The bq51025 device provides a single device
power conversion (rectification and regulation) as well as the digital control and communication for WPC
specification. The kit enables designers to speed up the development of their end-applications.
Contents
1 Introduction ................................................................................................................... 2
2 Considerations with this EVM.............................................................................................. 3
3 Modifications.................................................................................................................. 4
4 Recommended Operating Conditions..................................................................................... 4
5 Equipment and EVM Setup................................................................................................. 5
5.1 Schematic............................................................................................................ 5
5.2 Recommended Test Equipment .................................................................................. 6
5.3 Equipment Setup.................................................................................................... 6
5.4 Connector Descriptions ............................................................................................ 7
5.5 Jumpers and Switches............................................................................................. 7
5.6 Test Point Descriptions ............................................................................................ 8
5.7 Pin Description of the IC .......................................................................................... 9
6 Test Procedure ............................................................................................................. 10
6.1 Definition............................................................................................................ 10
6.2 Procedure .......................................................................................................... 10
7 Test Results................................................................................................................. 14
7.1 Steady-State Operation with the bq24261 Charger .......................................................... 14
7.2 Load Step .......................................................................................................... 15
7.3 Start Up............................................................................................................. 16
7.4 Efficiency Data..................................................................................................... 17
7.5 Adapter Insertion and Removal ................................................................................. 17
7.6 Thermal Performance............................................................................................. 18
8 Layout and Bill of Material ................................................................................................ 19
8.1 bq51025 Traces .................................................................................................. 19
8.2 Layout Guidelines ................................................................................................. 19
8.3 Printed-Circuit Board Layout Example ......................................................................... 19
8.4 bq51025EVM-649 Layout ........................................................................................ 21
8.5 Bill of Materials (BOM)............................................................................................ 24
List of Figures
1 bq51025EVM-649 Schematic .............................................................................................. 5
2 Placement of PWR649 on PWR648..................................................................................... 11
3 bq51025 in Steady State Operation with bq24261 .................................................................... 14
4 1-A Load Step .............................................................................................................. 15
5 1.4-A Load Step ........................................................................................................... 15
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Introduction www.ti.com
6 Start Up With 1000 mA ................................................................................................... 16
7 Start Up With 1400 mA ................................................................................................... 16
8 System Efficiency Versus Output Power ............................................................................... 17
9 Adapter Insertion and Removal .......................................................................................... 17
10 Thermal Image (1400-mA Load) ........................................................................................ 18
11 bq51025EVM-649 Layout Example ..................................................................................... 20
12 bq51025EVM-649 Top Assembly ....................................................................................... 21
13 bq51025EVM-649 Layer 1 ................................................................................................ 21
14 bq51025EVM-649 Layer 2 ................................................................................................ 22
15 bq51025EVM-649 Layer 3 ................................................................................................ 22
16 bq51025EVM-649 Layer 4 ................................................................................................ 23
List of Tables
1 bq51025EVM-649 Recommended Operating Conditions .............................................................. 4
2 Pin Description............................................................................................................... 9
3 bq51025EVM-649 Bill of Materials ...................................................................................... 24
1 Introduction
The bq51025 is an advanced, flexible, secondary-side device for wireless power transfer applications
capable of sourcing up to 10 W. The bq51025 device integrates an ultra-low-impedance synchronous
rectifier, a very-high-efficiency post regulator, digital control, and accurate voltage and current loops. The
bq51025 devices provide the AC/DC power conversion while integrating the digital control required. The
IC complies with the WPC v1.1 communication protocol.
Together with a bq500xxx primary-side controller transmitter (or any other WPC v1.1 transmitter), the
bq51025 enables a complete contactless power transfer system for a 5-W wireless power supply solution.
By utilizing near-field inductive power transfer, the secondary coil embedded in the mobile device can pick
up the power transmitted by the primary coil. The voltage from the secondary coil is then rectified and
regulated to be used as a power supply for down-system electronics. Global feedback is established from
the secondary to the primary in order to control the power transfer process.
In WPC, system communication is digital (packets are transferred from the secondary to the primary).
Differential bi-phase encoding is used for the packets. The bit rate is 2 kb/s. Various types of
communication packets have been defined. These include identification and authentication packets, error
packets, control packets, power usage packets and efficiency packets, among others.
When paired with the bq500215 primary-side controller transmitter, the bq51025 is capable of delivering
up to 10 W. The bq51025 incorporates a proprietary two-way authentication with the bq500215 primary
controller that allows optimal power transfer and system performance up to 10-W output power.
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www.ti.com Considerations with this EVM
2 Considerations with this EVM
The bq51025EVM-649 evaluation module (PWR649) demonstrates the receiver portion of the wireless
power system. This receiver EVM is a complete receiver-side solution that produces 10-W output power at
up to 2-A load with adjustable output voltage. The 10-W output power can be delivered from various
output voltages. The output current is limited so that the overall delivered power is less than 10 W. For
example, a 10-V output can supply up to 1 A, whereas a 5-V output can deliver up to 2 A. The default
configuration for this EVM is a 7-V output capable of delivering up to 1.43 A.
• The receiver can be used in any number of devices as a power supply for a battery charger. With
contact-free charging capability, no connections to the charging power source are required.
• 5-W power delivery with any WPC v1.1 transmitter
• 10-W power delivery with the bq500215 transmitter
• Highly-integrated wireless power receiver solution
– Ultra-efficient synchronous rectifier
– Very high efficiency post regulator
– WPC v1.1-compliant communication and control
– Only one IC required between RX coil and DC output
• Programmable output voltage to optimize performance for application
• Adaptive communication current limit (CM_ ILIM) for robust communication
• Supports 20-V max input
• Low-power dissipative overvoltage clamp
• Overvoltage, overcurrent, overtemperature protection
• Low-profile, external pick-up coil
• Frame is configured to provide correct receiver to transmitter spacing
• Room above coil for testing with battery, key for Foreign Object Detection (FOD) tuning
• Options to adjust the input current limit and output voltage using resistors or I2C
• Flexibility for FOD tuning
• Adjustable resistor that can be used to set RFOD
• Temperature sensing can be adjusted using external resistors
• Micro-USB connector for adapter testing configuration
• I2C connector (USB-TO-GPIO "HPA172" kit for I2C communication through computer is required)
• WPG LED indicator (Green LED is on when VOUT is high)
• PD_DET LED indicator (Orange LED is on when the RX is on TX pad)
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Modifications www.ti.com
3 Modifications
See the bq51025 data sheet (SLUSBX7) when changing components. To aid in such customization of the
EVM, the board was designed with devices having 0402 and 0603 or larger footprints. A real
implementation likely occupies less total board space.
Note that changing components can improve or degrade EVM performance. Special attention should be
given to the resonant capacitors (C1, C2, and C3). Thermal performance of these capacitors can greatly
impact overall system performance.
4 Recommended Operating Conditions
Table 1 provides a summary of the bq51025EVM-649 performance specifications. All specifications are
given for an ambient temperature of 25°C.
Table 1. bq51025EVM-649 Recommended Operating Conditions
PARAMETER TEST CONDITION MIN TYP MAX UNIT
VRECT RECT voltage range 4 11 V
IOUT Output current Current limit programming range 2 A
IAD_EN Sink current 1 mA
POUT = 10 W with the bq500215 transmitter
VOUT(REG) Programmable output voltage(1) 4.5 7 10 V
EVM (PWR648), otherwise POUT = 5 W
fsSwitching frequency 110 205 kHz
TJJunction temperature 0 125 °C
(1) The output voltage can be adjusted using I2C or the VIREG and VO_REG resistors. Also the coil needs to change for different
output voltage levels for optimal operation of the EVM. See the bq51025 datasheet for details.
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PWR649A.SchDoc
Sheet Title:
Size:
Mod. Date:
File:
Sheet: of
Bhttp://www.ti.com
Contact: http://www.ti.com/support
bq51025EVM-649Project Title:
Designed for:Public Release
Assembly Variant:001
© Texas Instruments2014
Drawn By:
Engineer:
D. Stacey
D. Stacey
Texas Instruments and/or its licensors do not warrant the accuracy or completeness of this specification or any information contained therein. Texas Instruments and/or its licensors do not
warrant that this design will meet the specifications, will be suitable for your application or fit for any particular purpose, or will operate in an implementation. Texas Instruments and/or its
licensors do not warrant that the design is production worthy. You should completely validate and testyour design implementation to confirm the system functionality for your application.
Not in version controlSVN Rev:
PWR649Number: Rev: A
GND
BOOT1
RECT
BOOT2
BOOT2
OUT
BOOT1
CLMP1
AD
FOD
VIREG
CLMP2
COMM1
AD_EN
/WPG
COMM2
VO_REG
CM_ILIM
TS/CTRL
CLMP1
0.47µF
C9
0.47µF
C12
CLMP2
COMM2
COMM1 GND
GND
VO_REG
1
2
J5
GND
0.1µF
C19
GND
TS/CTRL
GND
VIREG
TP5
DNP
TP6
DNP
1.50k
R7
RECT
/WPG
GND GND
FOD
TP8
1
2
3
JP1 ADJ
TS/CTRL
GND
ILIM
FIX
1
2
J3
1
2
J4
GND
GND
0.1µF
C16
TP3
GND
OUT
GNDGND
AD_EN
RECT
1µF
C17
GND
GND
GND
OUT
FOD
AC1
AC2
Orange
D2
Green
D1
1
2
3
4
5
6
7
8
9
10
11
J1
OUT
AD
GND
10.0k
R11
22µF
C14
22µF
C15
OUT
3.3µF
C7
2.2µF
C21
500 Ohm
R5
500 Ohm
R6
0.047µF
C1
0.056µF
C8
1500pF
C4
100pF
C5
0.056µF
C13
1 2
3 4
5 6
7 8
9 10
J2
/WPG
PD_DET
GND SDASCL
PD_DET
PMODE
0.082µF
C3
0.068µF
C2
DNP
RECT
150k
R17
CM_ILIM
130k
R18
5.62Meg
R13
500 Ohm
R14
GND
976k
R1
PMODE
Q2
CSD13201W10
1
2
3
JP2
GND
CM_ILIM
High
Low
CM_ILIM
GND
1µF
C20
102k
R3
5.1V
D3
BZT52C5V1T-7
GND
TP1
SDA
SCL
TP4
237
R4
0
R15
DNP
TP2
20.0k
R16
OUT
TP9
150
R2
0.1µF
C6
0.1µF
C18
0.015µF
C10
0.015µF
C11
TP7
10.0k
R10
10.0k
R12
130k
R19
TP10
TP11
A1
A2 A3 B3 B2 C2 C3
C1
B1
Q1
CSD75207W15
PGND
A1
PGND
A2
PGND
A3
PGND
A4
PGND
A5
PGND
A6
AC1
B1
AC1
B2
AC1
B3
AC2
B4
AC2
B5
AC2
B6
BOOT1
C1
RECT
C2
RECT
C3
RECT
C4
RECT
C5
BOOT2
C6
OUT
D1
OUT
D2
OUT
D3 OUT D4
OUT D5
OUT D6
CLAMP1 E1
AD E2
AD_EN E3
SCL E4
VIREG E5
CLAMP2 E6
COMM1 F1
FOD F2
PMODE F3
SDA F4
WPG F5
COMM2 F6
VO_REG G1
ILIM G2
CM_ILIM G3
TS/CTRL G4
TMEM G5
PD_DET G6
U1
bq51025YFP
TP12
200
R8
200
R9
www.ti.com Equipment and EVM Setup
5 Equipment and EVM Setup
5.1 Schematic
Figure 1 shows the PWR649 schematic with the bq51025 output set to 7 V.
Figure 1. bq51025EVM-649 Schematic
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5.2 Recommended Test Equipment
The following equipment is needed to complete this test procedure:
Power Supplies
• Power supply #1 (PS #1) capable of supplying 12 V at 2 A is required (for bq500215EVM-648 10-W
transmitter)
• Power supply #2 (PS #2) capable of supplying 5 V at 2 A is required (for bq500212AEVM-550 5-W
transmitter)
• Power supply #3 (PS #3) capable of supplying 5 V at 1 A is required (for adapter testing)
Loads
• For simplicity, resistive loads should be used that can be set to 5 Ω/1400 mA, 14 Ω/500 mA, and 7
kΩ/1 mA. The power rating should be 10 W. An electronic load will work as well, but the discussion
focuses on the resistive load setup.
• The default setting for this EVM is for a 7-V output. Changing this value will require additional changes
to the EVM including a different coil. Details can be found in the bq51025 datasheet.
Meters
• Three DC voltmeters, two DC ammeters and one ohmmeter
Oscilloscopes
• Not required but can be used to view traces as needed
bqTesla Transmitters
• The PWR648 transmitter (bq500215EVM-648) is required for 10-W testing and requires a 12-V input
supply (PS #1)
• The PWR550 transmitter (bq500212AEVM-550) is recommended for 5-W testing and requires a 5-V
input supply (PS #2). Any other WPC v1.1 transmitter can be substituted (care must be given to the
required input power supply).
Recommended Wire Gauge
• For proper operation, TI recommends 22-AWG wire or larger
5.3 Equipment Setup
The following items ensure proper equipment setup:
Test Set Up
• Set power supplies to OFF
• 10-W testing will be done with the PWR648 transmitter. Input voltage to the PWR648 is set with PS #1
to 12 VDC ±200 mV, with a current limit of 2.0 A.
• Connect PS #1 positive terminal to J1 and negative terminal to J2 of PWR648
• 5-W testing will be done with the PWR550 transmitter. Input voltage to the PWR550 is set with PS #2
to 5 VDC ±200 mV, with a current limit of 2.0 A.
• Connect PS #2 positive terminal to J1 and negative terminal to J2 of PWR550
Load
• The load is connected between J3-OUT and J4-GND of PWR649
• A DC ammeter is connected between PWR649 and load
Jumper Settings
• JP1 →ILIM and FIX are shorted
• JP2 →CM_ILM and High are shorted
Voltage and Current Meters
• Connect the ammeter to measure PS #1 (12-V input) current to the PWR648. Connect the voltmeter to
monitor the input voltage at J1 and J2 of PWR648 unit.
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• A voltmeter is used on the PWR649 to measure output voltage at J3 with ground at J4. Connect the
ammeter to measure load current.
• When 5-W testing is to be done, connect the ammeter to measure PS #2 (5-V input) current to the
PWR550. Connect the voltmeter to monitor the input voltage at J1 and J2 of PW550 unit.
RFOD: R6 Set Up
• Connect the ohmmeter between TP8 (FOD) and TP9 (GND). Verify R2 + R6 is approximately 256 Ω;
adjust, if necessary.
5.4 Connector Descriptions
The connections points are described in the following paragraphs.
5.4.1 J1 – AD External Adapter Input
Power can be provided to simulate an external adapter applied to the receiver in this bq51025EVM-649
(PWR649).
5.4.2 J2 – Programming Connector
This connector is populated and can be used for I2C communication using the USB-TO-GPIO "HPA172"
kit.
5.4.3 J3 – Output Voltage
Output voltage in wireless power mode up to 2 A (default configuration limits to 1.4 A at 7 V); the adapter
option is also supported in this PWR649.
5.4.4 J4 –GND
Ground return
5.4.5 J5 – TS/CTRL and Return Connector
External connection for temperature sense resistor, see data sheet for additional information.
5.5 Jumpers and Switches
The control jumpers are described in the following paragraphs.
5.5.1 JP1– ILIM (FIX or ADJ)
Maximum output current is set by the ILIM pin. In the FIX position, the current is set to a fixed value of R4
plus RFOD (R2 + R6 as set by the factory) (approximately 1.4 A). In the ADJ position, current is set by R5
and R14 along with RFOD.
5.5.2 JP2 – CM_ILIM
Enables CM_ILIM feature when pulled low and disables when pulled high. Default position is high
(disabled).
7
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5.6 Test Point Descriptions
The test points are described in the following paragraphs:.
5.6.1 TP1, TP2, TP4, and TP9 – Ground
These test points are used for ground connections.
5.6.2 TP3– Rectified Voltage
The input AC voltage is rectified into unregulated DC voltage (VRECT); additional capacitance is used to
filter the voltage before the regulator.
5.6.3 TP5 and TP6 – AC1 and AC2 Inputs
Test points are not populated, they can be used for measuring AC voltage applied to the EVM from the
receiver coil. These points are used for connecting the receiver's coil.
5.6.4 TP7– PMODE
Indicator of power mode, low if in 10-W mode, high if in 5-W mode. Pin F3 of the bq51025.
5.6.5 TP8 – FOD
Input for rectified power measurement for FOD feature in WPC, pin F2 of the IC. TP8 is the FOD pin of
the bq51025.
5.6.6 TP10– ILIM
Programming pin for overcurrent limit protection, pin G2 of the bq51025.
5.6.7 TP11– 10-W ILIM
Allows individual trimming of R5 and R14 for optimum power delivery for 5-W and 10-W systems.
5.6.8 TP12– Input Power
Connected to J1 pin 1. Alternative connection for wired power.
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5.7 Pin Description of the IC
Table 2 contains the pin descriptions.
Table 2. Pin Description
PIN Number (WCSP) bq51025
A1, A2, A3, A4, A5, A6 PGND
B1, B2, B3 AC1
B4, B5, B6 AC2
C1 BOOT1
C2, C3, C4, C5 RECT
C6 BOOT2
D1, D2, D3, D4, D5, D6 OUT
E1 CLAMP1
E2 AD
E3 AD_EN
E4 SCL
E5 VIREG
E6 CLAMP2
F1 COMM1
F2 FOD
F3 PMODE
F4 SDA
F5 WPG
F6 COMM2
G1 VO_REG
G2 ILIM
G3 CM_ILIM
G4 TS/CTRL
G5 TMEM
G6 PD_DET
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Test Procedure www.ti.com
6 Test Procedure
This procedure describes the test configuration of the bq51025EVM-649 evaluation board (PWR649) for
bench evaluation.
6.1 Definition
The following naming conventions are used:
VXXX : External voltage supply name (VBAT, VTS, VOUT)
LOADW: External load name (LOADR, LOADI)
V(TPyy): Voltage at internal test point TPyy. For example, V(TP02) means the voltage at TP02.
V(Jxx): Voltage at header Jxx
V(TP(XXX)): Voltage at test point XXX. For example, V(TP(ACDET)) means the voltage at the test
point which is marked as ACDET.
V(XXX, YYY): Voltage across point XXX and YYY
I(JXX(YYY)): Current going out from the YYY terminal of header XX
Jxx(BBB): Terminal or pin BBB of header xx
JPx ON : Internal jumper Jxx terminals are shorted
JPx OFF: Internal jumper Jxx terminals are open
JPx (-YY-) ON: Internal jumper Jxx adjacent terminals marked as YY are shorted
UUT: Unit Under Test (PWR649 EVM)
Assembly drawings have locations for jumpers, test points, and individual components.
6.2 Procedure
The following operating procedures are provided at a variety of operating loads. Initial testing is done with
the 10-W transmitter (PWR648).
Figure 2 shows the proper alignment between the transmitter (PWR648) and receiver (PWR649).
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TX
PWR648A
RX
PWR649A
www.ti.com Test Procedure
Figure 2. Placement of PWR649 on PWR648
Turn ON Operation and Operation at 1400-mA Load (approximately 10 W)
• Turn ON transmitter power supply PS #1 (12 V)
• Wait approximately 1 second for the transmitter to start
• Transmitter – Verify LED D2 is blinking and D6 is OFF
• UUT – Adjust load current to 1400 mA ±50 mA
• Place the UUT on center of the PWR648 TX coil
• After about 1 second, verify that:
– The transmitter should beep
– Transmitter – LED D2 (green) is ON and LED D6 (green) is blinking (about 2 times per second)
– Receiver – LED D1 (green) is ON and LED D2 (orange) is ON
– UUT – Verify that VOUT is 6.9 V to 7.2 V (between J3 and J4)
– UUT – Verify that the voltage between TP7 and TP2 (ground) measures less than 0.1 V (verifies
10-W mode)
– UUT – Verify that the rectified voltage is 7 V to 7.4 V (between TP3 and TP4) NOTE: a modulation
signal is present on this voltage every 250 ms and may cause fluctuation in the reading: use the
baseline value.
Efficiency Test (1400-mA Load)
• Verify that PS #1 input current is less than 1200 mA
• Note that if the CM_ILIM jumper (JP2) is set to low, the efficiency will be negatively impacted
• Remove UUT from the TX and turn OFF PS #1
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Turn ON Operation and Operation at 500-mA Load (approximately 3.5 W)
• Turn ON PS #1
• Wait approximately 1 second for transmitter to start
• Transmitter – Verify LED D2 is blinking and LED D6 is OFF
• UUT – Adjust load current to 500 mA ±50 mA
• Place the UUT on center of the PWR648 TX coil
• After about 1 second, verify that:
– The transmitter should beep
– Transmitter – LED D2 (green) is ON and LED D6 (green) is blinking (about 2 times per second)
– Receiver – LED D1 (green) is ON and LED D2 (orange) is ON
– UUT – Verify that VOUT is 6.9 V to 7.2 V (between J3 and J4)
– UUT – Verify that the rectified voltage is 7.0 V to 7.4 V (between TP3 and TP9) NOTE: a
modulation signal is present on this voltage every 250 ms and may cause fluctuation in the reading:
use the baseline value.
Efficiency Test (500-mA Load)
• Verify that PS #1 input current is less than 425 mA
• Remove UUT from the TX and turn OFF PS #1
Operation (1-mA Load)
• Turn ON PS #1
• Wait approximately 1 second for transmitter to start
• Transmitter – Verify LED D2 is blinking and LED D6 is OFF
• UUT – Adjust load current to 1 mA ±200 µA
• Place the UUT on center of the PWR648 TX coil
• After about 1 second, verify that:
– The transmitter should beep
– Transmitter – LED D2 (green) is ON and LED D6 (green) is blinking (about 2 times per second)
– Receiver – LED D1 (green) is ON and LED D2 (orange) is ON
– UUT – Verify that VOUT is 6.9 V to 7.2 V (between J3 and J4)
– UUT – Verify that the rectified voltage is 8.0 V to 10.0 V (between TP3 and TP9) NOTE: a
modulation signal is present on this voltage every 250 ms and may cause fluctuation in the reading:
use the baseline value.
Efficiency Test (1-mA Load)
• Verify that PS #1 input current is less than 110 mA
• Remove UUT from the TX and turn OFF PS #1
Adapter Test (500-mA Load)
• Initial adapter testing will be done without the transmitter
• Connect 5 V ±250 mV adapter on J1 on the bq51025EVM-649 receiver (or use TP12 / PS #3 and
GND)
• Adjust the load current to 500 mA ±50 mA (J3 OUT and J4 GND)
• Verify that:
1. UUT – LED D1 is OFF and LED D2 is OFF
2. UUT – VOUT is 5.0 V ±600 mV (J3 to J4)
• Turn ON PS #1
• Wait approximately 1 second for transmitter to start
• Transmitter – LED D2 is blinking and LED D6 is OFF
• Place the UUT on center of the PWR648 TX coil while the adapter is still connected to J1 (or TP12)
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• After 1 second verify that:
– The transmitter should NOT beep
– Transmitter – LED D2 is ON and LED D6 is OFF
– Receiver – LED D1 is OFF and LED D2 is ON
– UUT – Verify that VOUT is 4.9 V to 5.2 V (between J3 and J4)
– This shows that wireless power is disabled
• Keep the UUT on the transmitter and remove the power on J1 (or TP12) of the UUT
• After approximately 1 second verify that:
– The transmitter should beep
– Transmitter – LED D2 is ON and LED D6 is blinking
– Receiver – LED D1 is ON and LED D2 is ON
– UUT – Verify that VOUT is 6.8 V to 7.2 V (between J3 and J4)
– This shows that wireless power is enabled
• Remove UUT from the TX and turn OFF PS #1
5-W Transmitter Test (500-mA Load)
• The UUT will be tested with the 2nd transmitter - PWR550
• The PWR550 EVM requires a 5-V supply with a 2.0-A current limit (PS #2)
•NOTE: Any other 5-W transmitter can be substituted, but the discussion from the transmitter side is
only relevant to the PWR550 EVM
• Connect 5 V ±100 mV adapter on J1 on the PWR550 transmitter
• Place the UUT in the center of the PWR550 TX coil
• Adjust the load current to 500 mA ±50 mA (J3 OUT and J4 GND)
• Turn ON PS #2
• After approximately 1 second, verify that:
1. PWR550 – LED D1 (blue) is ON, LED D5 (green) is blinking about once per second
2. UUT – LED D1 is ON and LED D2 is ON
3. UUT – VOUT is 6.9 V to 7.2 V (J3 to J4) (approximately 3.5 W)
4. UUT – TP7 to TP2 (ground) measures above 1.5 V (this verifies that the receiver is in 5-W mode)
• Verify the maximum power is limited with the 5-W transmitter
1. Slowly increase load current towards 900 mA (towards 6 W)
2. Before 900 mA is reached, VOUT of the PWR649 will begin to decrease towards 6.0 V (J3 to J4)
indicating maximum power is reached
• Remove UUT from the TX and turn OFF PS #2
13
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bq51025 IOUT bq51025 VOUT
bq24261 IOUT (Battery)
bq24261 VOUT (Battery)
bq51025 POUT (7 V * 1.4 A) ~10 W
bq24261 POUT (4 V * 2.1 A) ~8.4 W
Test Results www.ti.com
7 Test Results
7.1 Steady-State Operation with the bq24261 Charger
With the power supply off, connect the supply to the bqTESLA transmitter.
• Set up the test bench as described in Section 6
• Power the TX (PWR648) with 12 V
• Connect the output of the RX (PWR649) to battery charger bq24261EVM-079
• Using a source meter, set the VBAT to 3.5 V and the current limit to 3.5 A
• Using the bq24261 GUI, set the charger current to 2.1 A and the current limit to 2.5 A
• Monitor the IOUT and VOUT from the RX after putting the receiver EVM (PWR649) on the transmitter coil
and aligning them correctly
• Monitor the IOUT and VOUT from the bq24261
•Figure 3 shows the VOUT and IOUT from both the RX and the bq24261EVM-079. The output power from
the bq51025 is approximately 10 W while the output power from the bq24261 is approximately 8.4 W.
Figure 3. bq51025 in Steady State Operation with bq24261
14 bq51025 Evaluation Module (PWR649) SLUUB55–September 2014
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RECT
OUT
IOUT
RECT
OUT
IOUT
www.ti.com Test Results
7.2 Load Step
The procedure for load step is as follows:
• Set up the test bench as described in Section 6
• Power the TX (PWR648) with 12 V
• Provide a load step from no-load (high impedance) to 1000 mA by attaching a 7-Ωresistive load
between J3 and J4 of the PWR649 EVM
• Monitor the RX signals: load current (IOUT), rectifier voltage (RECT), and output voltage (OUT) as
shown in Figure 4
• A 1.4-A load step is shown in Figure 5. Note that this step requires more time to recover to the full
output voltage.
Figure 4. 1-A Load Step
Figure 5. 1.4-A Load Step
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RECT
OUT
IOUT
RECT
OUT
IOUT
Test Results www.ti.com
7.3 Start Up
The procedure for start-up test with load:
• Set up the test bench as described in Section 6
• Power the TX (PWR648) with 12 V
• Apply 7 Ωacross J3 and J4 on PWR649 to generate a 1-A load
• Put the RX (PWR649) on the transmitter coil, and align them correctly
• Monitor the RECT pin, IOUT, and output voltage (OUT), as shown in Figure 6
• Starting up with a 5 Ωat J3 to J4 generates a 1.4-A load and is shown in Figure 7
Figure 6. Start Up With 1000 mA
Figure 7. Start Up With 1400 mA
16 bq51025 Evaluation Module (PWR649) SLUUB55–September 2014
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V(Adapter)
OUT
IOUT
Add Adapter Remove Adapter
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
0 2 4 6 8 10 12
Efficiency
Power Out (W)
bq500212A
bq500215
C001
www.ti.com Test Results
7.4 Efficiency Data
Figure 8 illustrates the system (DC-DC) efficiency of the bq51025EVM-649 using the bq500212AEVM-550
5-W transmitter and the bq500215EVM-648 10-W tranamitter.
Figure 8. System Efficiency Versus Output Power
7.5 Adapter Insertion and Removal
Figure 9 illustrates the behavior of the bq51025EVM-649 when an adapter is inserted into J1 (or at TP12)
while the EVM is on the transmitter pad with a resistive load at J3 to J4. There is some off time during the
transitions between wireless power and wired power modes.
This illustration starts with no adapter. IOUT is approximately 500 mA with OUT at 7 V. At 1.2 seconds of
the plot, adapter power is added. The output changes from the 7-V wireless output voltage to the 5-V
adapter voltage. With the resistive load, the output current drops proportionately. At about 2.3 seconds the
adapter is removed. The restart time for wireless power is about 1 second.
Figure 9. Adapter Insertion and Removal
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Test Results www.ti.com
7.6 Thermal Performance
This section shows a thermal image of the bq51025EVM-649. A 1.4-A load is used and the output voltage
is set to 7 V (approximately 10 W). There is no air flow and the ambient temperature is 25°C. The peak
temperature of the device (41.4°C) is well below the maximum recommended operating condition listed in
the data sheet.
Figure 10. Thermal Image (1400-mA Load)
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www.ti.com Layout and Bill of Material
8 Layout and Bill of Material
8.1 bq51025 Traces
The bq51025 device pins can be classified as follows:
•Signal/Sensing Traces
– TS/CTRL, PD_DET, WPG, COMM1, COMM2, ILIM, AD, AD_EN, FOD, TMEM, CM_ILIM,
VO_REG, VIREG, PMODE, SCL, and SDA
– Make sure these traces are isolated from the noisy traces
•Noisy Traces
– AC1, AC2, BOOT1, BOOT2, COMM1, and COMM2
– Make sure these traces are isolated from other traces, use ground plane
•Power Traces
– AC1, AC2, OUT, CLAMP1, CLAMP2, and PGND
– Make sure to use the correct width for the right current rating
8.2 Layout Guidelines
Use the following layout guidelines:
• The traces from the input connector to the inputs of the bq51025 device pin should be as wide as
possible to minimize the impedance in the lines. Otherwise, this may cause the voltage to drop and
could cause thermal issues.
• Keep the trace resistance as low as possible on AC1, AC2, OUT, and PGND
• Use the appropriate current rating traces (width) on AC1, AC2, OUT, and PGND
• The PCB should have a ground plane (return) connected directly to the return of all components
through vias (At least two vias per capacitor for power-stage capacitors, one via per capacitor for
small-signal components).
• Dissipation of heat is very important. The layout must allow for transfer of heat from high power items.
Adding internal layers increases the thermal performance. Multiple vias in the PGND pins of the IC is
recommended to decrease the thermal resistance in the board and allow much easier thermal
dissipation through inner layer and power ground layers.
• The via interconnect is important and must be optimized near the power pad of the device and ground
• 2-oz copper, or greater, is recommended
• For high-current applications, the balls for the power traces should be connected to as much copper in
the board as possible. This allows better thermal performance because the board conducts heat away
from the device.
• It is always good practice to place high frequency bypass capacitors next to RECT and OUT
8.3 Printed-Circuit Board Layout Example
The primary concerns when laying a custom receiver PCB are as follows:
• AC1 and AC2, GND return trace resistance
• OUT trace resistance
• GND connection
• Copper weight ≥2 oz
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AC1
AC2
OUT AD
GND
GND
GND
Keep the trace
resistance as low as
possible on AC1, AC2
and OUT
Isolate noisy traces
using GND path
R
R
R
D D
CO
CP
B
CO
CP
B
RECT
GND
Signal and sensing
components should
be placed as close to
the device as possible
High frequency bypass
capacitors should be
placed close to RECT
and OUT
Via interconnects are
used to aid in thermal
dissipation tuse
where possible
COMM, CLAMP and
BOOT capacitors are
placed as close to the
device as possible
Detection and
Resonant
capacitors
should be
placed as close
to the device as
possible
AD trace to
wired power
bypass FET is a
power path
bq51025YFP
Layout and Bill of Material www.ti.com
For a 1.4-A fast charge current application, the current rating for each net is as follows:
• AC1 = AC2 = 2.2 A
• BOOT1 = BOOT2 = 1 A
• RECT = 200 mA (RMS)
• OUT = 2.5 A
• COMM1 = COMM2 = 600 mA
• CLAMP1 = CLAMP2 = 1000 mA
• ILIM = 10 mA
• AD = AD_EN = TS/CTRL = FOD = 1 mA
TI also recommends having the following capacitance on RECT and OUT:
• RECT ≥22 μF
• OUT ≥1μF
It is always good practice to place high-frequency bypass capacitors next to RECT and OUT of 0.1 μF.
Figure 11 illustrates an example of a WCSP layout.
Figure 11. bq51025EVM-649 Layout Example
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