DV2954S1H Li-Ion Charger Development System Control of On-Board PNP Switch-Mode Regulator with High-Side Current Sensing Features ➤ bq2954 fast-charge control evaluation and development, based on switching buck converter with high-side battery-current sensing ➤ On-board configuration for fast charge of 1, 2, 3, or 4 Li-Ion cells ➤ Charge termination by maximum voltage, selectable minimum current, or maximum time-out ➤ Constant current (up to 1.25A) and constant voltage (up to 16.8V) provided by on-board switch-mode regulator ➤ Jumper-configurable bicolor-LED display ➤ Direct connections for battery and thermistor ➤ Maximum charge time of 5 hours General Description The DV2954S1H Development System provides a development environment for the bq2954 Lithium Ion FastCharge IC. The DV2954S1H incorporates a bq2954 and a buck-type switch-mode regulator to provide fast-charge control for 1–4 Li-Ion cells. Fast charge is preceded by a pre-charge qualification period. Connection Descriptions Fast charge termination occurs on: J1 ■ Minimum current – IMAX divided by 10, 15, or 20 DC+ Charger supply positive (24VDC max.) ■ Maximum time-out DC- Charger supply ground The bq2954 can be reset and a new charge cycle started by applicaton of power to the board or replacement of the battery. The board automatically initiates a recharge when the battery voltage drops to 3.85V per cell. J2 The user provides a DC power supply and batteries and configures the board for the number of cells, the minimum current threshold, and the LED display mode. The board has direct connections for the battery and the provided thermistor. Before using the DV2954S1H board, please review the bq2954 data sheet. 10/98 BAT+ Positive battery terminal TEM+ Postive thermistor connections GND Negative battery terminal and thermistor connecton. JP1 Ful current and minimum current termination-selection JP2 Display mode selection JP3 Number of cells selection Rev. C Board 1 DV2954S1H JP2: Configures the display mode (DSEL). Fixed Configuration The DV2954S1H board has the following characteristics: ■ VCC for the fast-charge IC is regulated onboard from the supply at connector J1. ■ J1 can accept a maximum of 24VDC. ■ LED indicates charge status. ■ Charge begins on the later application of – The battery – Supply voltage The regulated current is controlled by the value of the sense resistor RSNS according to the relationship 0.250 V = R SNS The value of RSNS (R20 in the schematic) at shipment is 0.200Ω. This resistor can be changed depending on the application. The maximum charging current IMAX for the DV2954S1H board is 1.25A. Jumper-Selectable Configuration JP1: Sets the full and minimum current termination. I MAX 1 [2 3] I MAX 123 I MAX 5 10 15 IMIN I MAX I MAX I MAX Number of Cells 1 2 3 4 1. Configure DSEL, maximum time-out, and the number of cells. 2. Connect the thermistor to TEM+ and GND. 3. Attach the battery pack to BAT+ and GND. 4. Connect the charging supply to J1. Number of Cells Minimum Charger Supply Input 1 2 3 4 7.5VDC 12VDC 18VDC 23VDC The combined charging and system load should not exceed the IMAX limit of 1.25A. The DV2954S1H can be configured as follows. (See Jumper Configuration Diagram for location of the jumpers.) IFULL JP3 [1 2 ] 3 4 5 6 7 8 1 2 [3 4] 5 6 7 8 1 2 3 4 [5 6] 7 8 1 2 3 4 5 6 [7 8] The following table shows the minimum input requirement for a given number of cells. The thermistor provided is a Philips 2322–640–63103. With this thermistor connected between TEM+ and GND, the temperature fault limits are VLTF (low-temperature fault) = 0°C, VHTF (high-temperature fault) = 45°C, and VTCO (charge cutoff) = 47°C. JP1 Mode 1 Mode 2 Mode 3 Setup Procedure The switching frequency of the PWM control loops is 120kHz. [1 2] 3 Display Mode JP3: Configures the board for the number of cells. The on-board regulator supplies a fast-charge current IMAX of 1.25A. The fast-charge voltage VMAX is set at 25°C. I CHG JP2 1 [2 3] [1 2] 3 123 10 15 20 Rev. C Board 2 DV2954S1H Jumper Configuration Diagram J2 7 J1 5 3 1 BAT+ DC+ TEM+ JP3 DC- GND 8 6 4 2 GND 3 2 JP1 JP2 1 3 2 1 BD2954JCD.eps DV2954S1H Board Schematic R5 Q3 2N3906 L2 ZTX789A 10K Q2 R1 10K 100µF 35V U3 100 1% D4 1K 1N5818 IN OUT GND C4 C5 1µF 35V 1µF 35V L1 D3 C11 1 2 3 4 10uH 1N4148 EZ Y1 E1 E4 ZTX789A R21 R22 R23 R24 52.3K 1% 154K 1% 255K 1% 357K 1% Q5 R8 1 U2 +5V 78L05ACZ 0.2 1/2w 5% R10 2N3904 R15 C3 R20 140UH 2K 8 7 6 5 E3 Y2 X2 X1 1 3 5 7 Q1 1N5818 1 2 C12 47µF 32V JP3 ZDS1009 2 4 6 8 R13 D2 J1 4.7K 2 0.1µF Q9 Q8 Q4 R12 2N3906 2N3906 ZTX451 C6 100 1% R25 1M R9 49.9K 1% 0.1µF +5V R16 220 R2 Q10 Q11 2N3904 4.32K 1% 2N3904 BAT+ TEM+ +5V 2N3904 +5V 10K C9 Q6 R3 R19 100K 4 3 2 1 J2 8.45K 1% R14 R18 +5V JP1 H +5V +5V 0.1µF 1 2 3 4 5 6 7 8 R4 10K 1 L TM LED2/DSEL LED1/CSEL CHG MOD BAT VCC VCOMP U1 VSS ICOMP LCOM ITERM BTST SNS TS TPWM ITERM C10 0.1µF 1 U2 is not used if Q8–Q11 are used. Q8–Q11 are not used if U2 is used. 2 Optional C1 0.1µF R11 100 1% C7 0.1µF bq2954 1K R7 RED 10K GREEN 1 2 3 D1 16 15 14 13 12 11 10 9 R6 10K Q7 2N3904 H JP2 L DSEL R17 10K C8 820PF Rev. C Board 3 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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