Table of Contents
Advertisement
Quick Links
UM0497
User manual
USB Li-Ion battery charger evaluation board
Introduction
This document explains the functioning of the USB-based single cell Li-Ion battery charger
evaluation board which consists of a ST7260E2-based low-speed USB controller and a
battery charger based on the ST7LIT15BY0.
The evaluation board includes a power selector circuit to select the appropriate power
supply source and a step-up converter circuit based on the L6920 device to provide a fixed
output voltage to the USB controller. The power supply for the battery charger controller is
generated from the TL1431programmable voltage reference, keeping in mind the accuracy
requirement for charging. An additional current limiter is also included in series with a USB
power supply to show any incorrect behavior using a status LED.
A provision is provided on evaluation board such that any external low-speed USB controller
can control the operation of the charger, hence this system can be used with any low-speed
USB controller.
The charger used in the board utilizes a modified form of non-inverting buck-boost converter
to support the charging voltage requirement for single cell Li-Ion battery. This converter is
explained in more detail in AN2390.
This evaluation board represents a complete USB-based portable battery charging system
for a single cell Li-Ion battery, such as those used in MP3 players.
There are separate ICP connectors provided on the board to reprogram the USB controller
and charger controller.
February 2008
Rev 1
1/21
www.st.com
Advertisement
Table of Contents
Subscribe to Our Youtube Channel
Related Manuals for ST ST7LIT15BY0
Summary of Contents for ST ST7LIT15BY0
- Page 1 This document explains the functioning of the USB-based single cell Li-Ion battery charger evaluation board which consists of a ST7260E2-based low-speed USB controller and a battery charger based on the ST7LIT15BY0. The evaluation board includes a power selector circuit to select the appropriate power supply source and a step-up converter circuit based on the L6920 device to provide a fixed output voltage to the USB controller.
-
Page 2: Table Of Contents
Contents UM0497 Contents Getting started ..........4 Package contents . - Page 3 UM0497 List of figures List of figures Figure 1. USB Li-Ion evaluation board (STEVAL-ISB003V1) ....... 4 Figure 2.
-
Page 4: Getting Started
Getting started UM0497 Getting started Package contents The USB Li-Ion battery charger evaluation board includes the following items: ● Hardware content: – One evaluation board ● Documentation: – User manual Hardware description Figure 1 below shows the snapshot of the evaluation board. Figure 1. -
Page 5: Precision Supply For The Charger
UM0497 Getting started This LED glows HIGH whenever the supply current increases from 500 mA. In the evaluation board, the current limiter is used only to show the status of whether the current limit is crossed or not, but it is not used to cut off the power supply. 1.2.3 Precision supply for the charger Figure 2... -
Page 6: Supply Generation Circuit For The Usb Controller
Getting started UM0497 1.2.5 Supply generation circuit for the USB controller Figure 4 shows L6920-based supply generation circuit for the USB controller. USB_SUPPLY is the output voltage and VREG (output voltage of the power selector circuit as in Section 1.2.4) is the input voltage of this circuit. The output voltage USB_SUPPLY is programmable. -
Page 7: Figure 5. Connector J2
J5 is used for selecting the clock source for the USB controller (ST7260E2) available in the evaluation board and J7 is used to select the clock source of the charger IC (ST7LIT15BY0). As shown in Figure 6, if we short pin 1 and 2 then the external resonator is used as the clock source and if we short pin 2 and pin 3, ICC clock is used as the clock source. -
Page 8: Dc-Dc Converter Circuit
DC-DC converter circuit Figure 7 shows the circuit diagram of the DC-DC converter circuit which is controlled by the two PWM signals coming from the charger controller ST7LIT15BY0. Figure 7. DC-DC converter circuit This DC-DC converter provides power to the single cell Li-Ion (3-pin battery pack) based on the battery voltage, current and temperature measurements. -
Page 9: Running The Evaluation Board
UM0497 Running the evaluation board Running the evaluation board After ensuring that all the jumpers are connected correctly as explained in the previous section, the evaluation board is ready to be used. Connecting to the PC As soon as you connect the USB connector to the evaluation board, you should find the evaluation board enumerated as an HID device as shown Figure Figure 8. -
Page 10: Connecting The Li-Ion Battery
Running the evaluation board UM0497 Figure 9. USB Li-Ion evaluation board HID This ensures that the evaluation board is connected properly to the USB and now ready to be used. Now we can proceed to the next steps. Connecting the Li-Ion battery The evaluation board is not provided with any specific slot in order to avoid making it package specific. -
Page 11: Battery Charging Status Monitoring
UM0497 Running the evaluation board Battery charging status monitoring There are two LEDS available (D8 and D9) on the evaluation board. Table 1 explains the behavior of these status LEDs according to the charging status. Table 1. Charging LED status SL NO Charging status Red LED (D8) - Page 12 Running the evaluation board UM0497 Table 2. Controlling/ changing the charging parameters (continued) File name: Bc.h For example: CurrentThre Current level during constant ----------------------------------- LION_ICONST Y = 120 for 300 mA current charging charging current. For example: CurrentThre Constant current level during pre- ----------------------------------- LION_ITRI_1 Y = 20 for 50 mA pre-...
-
Page 13: Using The External Usb Controller
UM0497 Using the external USB controller Using the external USB controller Before using the external USB controller, you must remove all jumpers (JP1, JP3, JP12, JP13, JP14 and JP15). After that you need to do the connections as mentioned in Section 1.2.7. -
Page 14: Using The Charger In Standalone Mode
Using the charger in standalone mode UM0497 Using the charger in standalone mode You can use the charger available in this evaluation board in standalone mode as well. In standalone, it provides an option of developing a low-cost battery charger which is capable of charging a single cell Li-ion battery from a 5 V power supply. -
Page 15: Warning/Limitation
UM0497 Warning/limitation Warning/limitation The limitations/warnings in using this evaluation board are as follows: The charging current is limited to 300 mA value using the USB supply. You can use an external supply for increasing the charging current by using it in standalone mode as mentioned in Section There is no protection for reverse battery polarity connection, but it can be provided... -
Page 16: Appendix A Schematic
Schematic UM0497 Appendix A Schematic Figure 11. Schematic 16/21... -
Page 17: Usb Battery Charger Bom
UM0497 Schematic USB battery charger BOM Table 3. Bill of materials Manufacturer’s Supplier‘s Value/generic part ordering code/ Index Qty Reference Package Manufact. Suppl. ordering number orderable part code number Electrolytic C1,C2 47 µF/16 V cylindrical Electrolytic 4.7 µF/25 V cylindrical C4,C5,C7, C8,C9,C1 0,C11,C1... - Page 18 Schematic UM0497 Table 3. Bill of materials (continued) Manufacturer’s Supplier‘s Value/generic part ordering code/ Index Qty Reference Package Manufact. Suppl. ordering number orderable part code number Axial 10 µH inductor Axial 33 µH inductor STT3PF30L SOT23-6L STT3PF30L Q1,Q2,Q3 2STR2215 SOT-23 2STR2215 Q4,Q5,Q6 ,Q7,Q8,...
- Page 19 UM0497 Schematic Table 3. Bill of materials (continued) Manufacturer’s Supplier‘s Value/generic part ordering code/ Index Qty Reference Package Manufact. Suppl. ordering number orderable part code number Top notch 3296 Push SW1,SW2 Reset button Single Test point berg pin ST890BDR SO-8 ST890BDR L6920D TSSOP8...
-
Page 20: Revision History
Revision history UM0497 Revision history Table 4. Document revision history Date Revision Changes 07-Feb-2008 Initial release 20/21... - Page 21 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.
Need help?
Do you have a question about the ST7LIT15BY0 and is the answer not in the manual?
Questions and answers