Texas Instruments BQ25756EEVM User manual

EVM User's Guide: BQ25756EEVM
BQ25756E Evaluation Module
Description
The BQ25756EEVM evaluation module (EVM) is a
complete evaluation system for the BQ25756E IC, a
buck-boost battery charge controller with a wide input
range of 4.2 V - 36 V, a wide output voltage range of
up to 36 V, and bi-directional capabilities.
The BQ25756EEVM has a max input and output of 36
V and a max charge current of 10 A.
Get Started
1. Order the EVM on ti.com
2. Order the EV2400 to communicate with the EVM
3. Download the BQ25756E BQZ file
4. Download the BQ25756E EVM design files on
ti.com
Features
• Wide input voltage operating range: 4.2 V–36 V
• Wide output operating range: up to 36 V with
CC/CV support for:
– 2– to 7–Cell Li-Ion
– 2– to 9–Cell LiFePO4
• Synchronous buck-boost DC/DC charge controller
with NFET drivers
– Adjustable switching frequency from 200 kHz to
600 kHz
– Optional synchronization to external clock
– Optional gate driver supply input for optimized
efficiency
• Resistor-programmable standalone with added I2C
Mode
• Built in MPPT to maximize power from solar panel
arrays
• Power up from battery (reverse mode) output 4 V
to 36 V
• High safety integration
– Adjustable input overvoltage and undervoltage
protection
– Output Overvoltage and overcurrent protection
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1 Evaluation Module Overview
1.1 Introduction
The BQ25756EEVM can be evaluated for up to 180 W range of USB Extended Power Range (EPR) and up to
7 cell Li-Ion battery charging implementing CC/CV profile. Typical applications include Kick eScooters, cordless
power tools, garden tools, robotic lawn mowers, portable power stations, cordless vacuum cleaners, vacuum
robots, solar chargers, and USB-PD EPR applications.
This EVM does not include the EV2400 or USB2ANY interface device and does not provide any electrical
isolation for the digital interfaces. EV2400 or USB2ANY must be ordered separately to evaluate the
BQ25756EEVM and electrical safety considerations must be considered when interfacing between the PC and
the EVM board. When interfacing the EVM to the PC through the digital interfaces, digital isolators with isolation
boundary is recommended.
The BQ25756EEVM has smaller clearance and creepage than normally used on high voltage boards as well as
not having an isolation boundary. If you apply high voltage to this board, all terminals must be considered high
voltage and hazardous live. Electric shock is possible when connecting the board to live wire. The board must be
handled with care by a professional. For safety, use of isolated test equipment with various protection features
(such as overvoltage and overcurrent) is recommended.
1.2 Kit Contents
This EVM kit includes:
• 1 BQ25756E EVM
1.3 Device Information
The BQ25756EEVM evaluation module (EVM) is an evaluation system for the BQ25756E IC. The BQ25756E IC
is a buck-boost battery charge controller with a wide input range of 4.2 V - 36 V, a wide output voltage range of
up to 36 V, and bi-directional capabilities.
The device offers high-efficiency battery charging over a wide voltage range with output CC-CV control. The
device integrates all the loop compensation for the buck-boost converter, thereby providing a high density
method with ease of use.
Besides the I2C host-controlled charging mode, the device also supports programmable hardware limits. Input
current, and output current regulation targets can be set with single resistor on the IIN, and IOUT pins,
respectively.
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1.4 General Texas Instruments High Voltage Evaluation (TI HV EMV) User Safety Guidelines
WARNING
Always follow TI's set-up and application instructions, including use of all interface components within their
recommended electrical rated voltage and power limits. Always use electrical safety precautions to help verify
your personal safety and those working around you. Contact TI's Product Information Center http://ti.com/
customer support for further information.
Save all warnings and instructions for future reference.
WARNING
Failure to follow warnings and instructions can result in personal injury, property damage or death
due to electrical shock and burn hazards.
The term TI HV EVM refers to an electronic device typically provided as an open framed, unenclosed printed
circuit board assembly. It is intended strictly for use in development laboratory environments, solely for qualified
professional users having training, expertise and knowledge of electrical safety risks in development and
application of high voltage electrical circuits. Any other use and/or application are strictly prohibited by Texas
Instruments. If you are not suitably qualified, then immediately stop from further use of the HV EVM.
1. Work Area Safety:
a. Keep work area clean and orderly.
b. Qualified observers must be present anytime circuits are energized.
c. Effective barriers and signage must be present in the area where the TI HV EVM and the interface
electronics are energized, indicating operation of accessible high voltages can be present, for the
purpose of protecting inadvertent access.
d. All interface circuits, power supplies, evaluation modules, instruments, meters, scopes, and other related
apparatus used in a development environment exceeding 50Vrms/75VDC must be electrically located
within a protected Emergency Power Off EPO protected power strip.
e. Use stable and non-conductive work surface.
f. Use adequately insulated clamps and wires to attach measurement probes and instruments. No
freehand testing whenever possible.
2. Electrical Safety:
a. As a precautionary measure, a good engineering practice to assume is that the entire EVM can have
fully accessible and active high voltages.
b. De-energize the TI HV EVM and all the inputs, outputs and electrical loads before performing any
electrical or other diagnostic measurements. Revalidate that TI HV EVM power has been safely de-
energized.
c. With the EVM confirmed de-energized, proceed with required electrical circuit configurations, wiring,
measurement equipment hook-ups and other application needs, while still assuming the EVM circuit and
measuring instruments are electrically live.
d. Once EVM readiness is complete, energize the EVM as intended.
WARNING
While the EVM is energized, never touch the EVM or the electrical circuits, as the electrical
circuits and EVM can be at high voltages capable of causing electrical shock hazard.
3. Personal Safety
a. Wear personal protective equipment e.g. latex gloves or safety glasses with side shields or protect EVM
in an adequate lucent plastic box with interlocks from accidental touch.
Limitation for safe use:
EVMs are not to be used as all or part of a production unit.
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1.4.1 General Safety Information
The following warnings and cautions are noted for the safety of anyone using or working close to the BQ25756E
EVM. Observe all safety precautions.
Warning
The BQ25756EEVM circuit module can become hot during operation due to dissipation of
heat. Avoid contact with the board. Follow all applicable safety procedures applicable to
your laboratory.
CAUTION
Hot surface. Contact can cause burns. Do not touch!
Warning
The BQ25756EEVM has smaller clearance and creepage than normally used on high
voltage boards as well as not having an isolation boundary. If the user applies high
voltage to this board, then all terminals are considered high voltage and hazardous live.
Electric shock is possible when connecting the board to live wire. The board needs to be
handled with care by a professional. For safety, use of isolated test equipment with various
protection features (such as overvoltage and overcurrent) is recommended.
Warning
High voltages that can cause injury exist on this evaluation module (EVM). Please verify all
safety procedures are followed when working on this EVM. Never leave a powered EVM
unattended.
Warning High voltage can be present on board capacitors after power down. Properly check and
discharge all on-board energy reservoir after EVM power down.
!
Caution Do not leave EVM powered when unattended.
CAUTION
The communication interfaces are not isolated on the EVM. The use of digital isolators is
recommended. Verify all high voltage safety precautions are observed during testing.
CAUTION
Connections for rated current must be made at the terminal block. Test points are not rated for the
board current.
CAUTION
The circuit module can be damaged by over temperature. To avoid damage, monitor the temperature
during evaluation and provide cooling, as needed, for your system environment. Do not operate
beyond the current and voltage limits in the Section 2.3.
CAUTION
Test equipment can be damaged by application of external voltages. Check your equipment
requirements and use blocking diodes or other isolation techniques, as needed, to prevent damage
to your equipment.
CAUTION
The circuit module has signal traces, components, and component leads on the bottom of the board.
This can result in exposed voltages, hot surfaces or sharp edges. Do not reach under the board
during operation.
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CAUTION
The default settings of the BQ25756E is possibly not designed for the user's application. Verify
the EVM settings are set appropriately for test setup before device power up. Set all protections
appropriately and limit current for safe operation.
CAUTION
The board does not have a fuse installed and relies on the external voltage source current limit to
verify circuit protection.
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2 Hardware
2.1 Board Parameters
Table 2-1. Default board setup for BQ25756EEVM
Description Value Unit
ACUV Input undervoltage 4.2 V
ACOV Input overvoltage 36 V
IIN Input current of the EVM 8 A
IOUT Output current of the EVM 10 A
FSW_SYNC Switching frequency of the power stage 250 KHz
Table 2-2. PCB and Mechanical Parameters
Value Unit
Board Size (X dimension, or length) 112 mm
Board Size (Y dimension, or width) 84 mm
IC + power stage max height 5 mm
Total Copper Layers 6 layer
Copper weight per layer 2 oz
Total board thickness 62 mil
2.2 IO and Jumper Descriptions
Table 2-3. Connector/Port Description
Jack Description
J1-VIN Input: positive terminal
J1-PGND Input: negative terminal (ground terminal)
J3-VOUT Connected to battery pack output
J3-PGND Ground
J4-EXT_I2C Communication port for the USB2ANY
J5-I2C Communication port for the EV2400
J6-EXT_DRV Connection for external gate drive
J7-Power Connector Connection for VAC and BAT
J8-Communication Port Connection for EXT_DRV, /INT, I2C, /PG, and 3.3 V
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Table 2-4. Jumper Description
Jumper Description Factory Default
JP1 Use JP1 to connect the default feedback resistor and set the charger to the default 7
cell battery Installed
JP2 Use JP2 to connect a new feedback resistor to program a different cell count Not installed
JP3 Use JP3 to connect external IOUT resistor. JP3 can be shorted to PGND to disable
hardware output current limiting.
Not installed
JP4 Shunt JP4 to use default IOUT resistor. By closing JP4, the default IOUT current is
set to 10 A.
Installed
JP5 Shunt JP5 to bias TS. Installed
JP6 With JP5 shunted (REGN connected for voltage divider). Shunt JP6 to set TS status
to normal.
Installed
JP7 With JP5 shunted (REGN connected for voltage divider). Use JP7 to connect
external resistor to change TS status.
Not installed
JP8 Use JP8 to connect external FSW_SYNC resistor. Not installed
JP9 Shunt JP9 to use default FSW_SYNC resistor. By closing JP9, the default switching
frequency is set to 250 kHz.
Installed
JP10 Shunt JP10 to use default IIN resistor. By closing JP10, the maximum input current
is set to 8 A.
Installed
JP11 Use JP11 to connect external IIN resistor. JP11 can be shorted to PGND to disable
hardware input current limiting.
Not installed
JP12
Use JP12 to select the gate driver source. Shunt pin1 to pin2 to use IC internal
LDO REGN output. Shunt pin2 to pin3 to use external gate drive supply. Maximum
external gate drive supply can be up to 11 V.
Pin1 and pin2 shunted
JP13 Shunt JP13 to enable controller in forward mode. Open JP13 to disable controller.
The /CE pin can also be used as a general purpose indicator.
Installed
JP14 Shunt JP14 to connect /INT to a pullup rail. Installed
JP15 Shunt JP15 to connect STAT1 to a pullup rail. The STAT1 pin can also be used as a
general purpose indicator.
Installed
JP16 Shunt JP16 to generate on board 3.3-V pullup rail. Installed
2.3 Recommended Operating Conditions
Table 2-5. Recommended Operating Conditions for BQ25756EEVM
Description MIN TYP MAX UNIT
VIN (J1) Input voltage to the EVM 4.2 36
(1) V
VOUT (J3) Output voltage of the EVM 3.3 36
(1) V
IIN (J1) Input current of the EVM 10(3) (4) A
IOUT (J3) Output current of the EVM 10(3) A
Regulator output power Output power of the EVM 360
(3) W
EXT_DRV (J6) Voltage applied to DRV_SUP pin of the regulator 4 11 V
EVM Operating Ambient
Temperature (TA) 25(2) °C
(1) Due to the high di/dt and dv/dt electrical flow associated with switch-mode power supplies, nodes on the EVM can have high spike
above input voltage (in buck mode) or output voltage (in boost mode) level. Switch node voltage can swing up to "input or output +
inductive spike" level. High side gate drives can swing up to "switch node voltage + 11 V (DRV_SUP supply voltage dependent) + gate
drive inductive spike" level. Safety precautions must be observed at all times.
(2) Connectors, bump-ons, jumpers on the EVM are not a good choice for evaluation under temperature greatly deviated from room
temperature of 25°C. Please refer to BOM for temperature rating of board components.
(3) Thermal monitoring (for example, using a thermal camera) is recommended if power stage output current > 5 A or total output power >
100 W.
(4) Default EVM input current limit is set to 8 A through the IIN pin. The current limiting feature can be disabled by setting EN_IIN_PIN bit
to '0', changing IIN pin resistor, or shorting IIN pin to PGND through JP11.
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2.4 Equipment
There are two recommended ways to test the EVM. The first and preferred way to test the EVM is to use a
four-quadrant power supply. The second is to use a electronic load in constant voltage mode. Testing with a
constant voltage load is covered in a later section. The following list of equipment is recommended when testing
with a four-quadrant power supply.
1. Power Supplies:
A power supply capable of supplying 40 V at 8 A is required. While this part can handle larger voltage and
current, larger power levels are not necessary for this procedure.
2. Load #1:
A Kepco load: BOP36-6M, DC 0 to ±36 V, 0 to ±6 A (or higher), or equivalent. When testing without a real
battery, connect 2000 uF of capacitance across the input.
3. Meters:
Six Fluke 75 multimeters, (equivalent or better) or: Three equivalent voltage meters and three equivalent
current meters.
4. Computer:
A computer with at least one USB port and a USB cable.
5. EV2400 Communication Kit:
6. Software:
Download and properly install bqStudio from https://www.ti.com/tool/BQSTUDIO.
2.4.1 Equipment Set Up
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Use the following guidelines to set up the equipment:
1. Set power supply #1 for 23 V DC, 8 A current limit and then turn off the supply.
2. Connect the output of power supply #1 in series with a current meter to J1 (VIN and PGND).
3. Connect a voltage meter across J1 (VIN) and J1 (PGND).
4. Connect load #1 in series with a current meter to J3 (VBAT and PGND).
5. Connect a voltage meter across J5 (VBAT and PGND).
6. Set 23 V at KEPCO load output. Limit KEPCO to 6 A. Use load #2 to power EVM from the VOUT output.
7. Connect J5 to the EV2400. Connect J5 to the I2C PORT 2 on the EV2400.
8. Make sure the jumpers are installed as indicated in IO and Jumper Descriptions.
9. Turn on the computer and load #2. Open the bqStudio software.
a. Select Charger and click the Next button.
b. Select Charger_1_00_BQ25756.bqz on the Select a Target Page.
c. After selecting the target device, click Field View. The main window of BQ25756E EVM software
appears.
d. Change I2C Address to D4(6A) and click Read Register.
10. Set WATCHDOG and EN_CHG to disabled.
11. In 16 Bit Registers, set ICHG_REG to 2000 mA and IPRECHG to 2000 mA.
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12. Turn on power supply #1, measure
V(J1(VAC)) = 30 V ± 0.5 V
I(J1(IAC)) = 1.6A ± 0.5 A
V(J3(VBAT)) = 23.5V ± 0.5 V
I(J3(IBAT)) = 2 A ± 0.5 A
13. Set power supply #1 for V, measure
V(J1(VAC)) = 23 V ± 0.5 V
I(J1(IAC)) = 2.1 A ± 0.5 A
V(J3(VBAT)) = 23.5 V ± 1 V
I(J3(IBAT)) = 2 A ± 0.5 A
14. Set power supply #1 for 10 V, measure
V(J1(VAC)) = 10 V ± 0.5 V
I(J1(IAC)) = 5.0 A ± 0.5 A
V(J3(VBAT)) = 23.5 V ± 1 V
I(J3(IBAT)) = 2 A ± 0.5 A
2.4.2 Equipment - Using a CV Load
The following list of equipment is recommended when testing with a constant voltage electronic load.
1. Power Supplies:
A power supply capable of supplying 40 V at 4 A is required. While this part can handle larger voltage and
current, larger power levels are not necessary for this procedure.
2. Load #1:
Kikusui PLZ164WA 0-150V, 0-33A When testing without a real battery, connect 2000 uF of capacitance
across the input.
3. Meters:
Six Fluke 75 multimeters, (equivalent or better) or: Four equivalent voltage meters and two equivalent
current meters.
4. Computer:
A computer with at least one USB port and a USB cable.
5. EV2400 Communication Kit:
6. Software:
Download and properly install bqStudio from https://www.ti.com/tool/BQSTUDIO.
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