MAY ? This is achieved by dynamically adjusting the battery charge current based on the total system adapter current. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. The selector function allows the manual selection of the system power source, battery or wall-adapter power.
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MAY ? This is achieved by dynamically adjusting the battery charge current based on the total system adapter current. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. The selector function allows the manual selection of the system power source, battery or wall-adapter power. It also provides autonomous switching to the remaining source battery or ac power should the selected system power source terminate refer to Table 1 for the differences between the bq and the bq Free-Air Temperature?
The JEDEC low K 1s board design used to derive this data was a 3-inch x 3-inch, two layer board with 2 ounce copper traces on top of the board. The JEDEC high K 1s board design used to derive this data was a 3-inch x 3-inch, multilayer board with 1 ounce internal power and ground planes and 2 ounce copper traces on top and bottom of the board.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to ground. Currents are positive into and negative out of the specified terminals. Consult the Packaging section of the data book for thermal limitations and considerations of the package. A www. Specified by design.
Not production tested. Total battery-current set is based on the measured value of SRP? Total ac-current set accuracy is based on the measured value of ACP? NOTES: 8. Refer to Table 1 to determine the logic operation of the bq and the bq H R20 0. Battery Plus R21 Note1 C11 22? R15 ? C12 Note1 35V R18 10? D2 BAS16 C3 1? R24 k? This input pin is used to determine the presence of the ac adapter.
This feature can be used to automatically select battery as the system power source. A logic high indicates there is a valid ac input. A low indicates the loss of ac power. This input selects either the ac adapter or the battery as the power source. A logic high selects ac power, while a logic low selects the battery. This input sets the system current level at which dynamic power management occurs.
Adapter currents above this programmed level activate the dynamic power management and proportionally reduce the available power to the battery. This open-drain pin indicates that a depleted battery condition exists. On the bq, the ALARM output also activates when the selector inputs do not match the selector state. In a no-battery condition, the bq automatically selects ac as the input source. BATP: Battery charge regulation voltage measurement input to the battery-voltage gm amplifier.
The voltage on this pin is typically derived from a voltage divider network connected across the battery. A high on this input pin allows PWM control operation to enable charging while a low on this pin disables and forces the PWM output to a high state.
The output of this pin produces a voltage proportional to the battery charge current. This voltage is suitable for driving an ADC input. These pins feed back the battery charge current for PWM control. SRN is tied to the battery terminal. SRP is the source pin for zero volt operation.
The level on this pin sets the battery charge current limit. VCC: Operational supply voltage. It can be used to set fixed levels on the inverting inputs of any one of the three error amplifiers if desired. The tight tolerance is suitable for charging lithium-ion batteries. VS: System Load voltage input pin. The voltage on this pin indicates the system voltage in order to insure a break before make transition when changing from ac power to battery power. This function can be eliminated by grounding the VS pin.
It minimizes battery charge time by allocating available power to charge the battery i. If the system plus battery charge current exceeds the adapter current limit, as shown in Figure 1, the DPM feature reduces the battery charge current to maintain an overall input current consumption within user defined power capability of the wall-adapter.
The DPM feature is inherently designed into the PWM controller by inclusion of the three control loops, battery-charge regulation voltage, battery-charge current, and adapter-charge current, refer to Figure 2. If any of the three user programmed limits are reached, the corresponding control loop commands the PWM controller to reduce duty cycle, thereby reducing the battery charge current.
Adapter and battery-charge current information is sensed and fed back to two transconductance gm amplifiers via low-value-sense resistors in series with the adapter and battery respectively.
Battery voltage information is sensed through an external resistor divider and fed back from the battery to a third gm amplifier. The host can set the precharge current externally by monitoring the ALARM pin to detect a battery depleted condition and programming SRSET voltage to obtain the desired precharge current level.
It is not designed to precharge depleted packs, as it is disabled at voltages that are not within normal pack operating range for precharge.
The battery charge current is limited by the filter resistor connected to SRP pin R R19 must be dimensioned to withstand the worst case power dissipation when in zero volt operation mode. Note, however, that R21 connected to SRN does not dissipate any power when in zero volt operation and can be of minimum size.
A constant current source. Refer to PWM selector switch gate drive section for gate drive voltage levels. Disabling the ?
A pullup reduces current drain when the PWM is disabled. A pullup is enabled refer to Figure 2. Compensation Voltage? V Figure 3 As any one of the three controlling loops approaches the programmed limit, the gm amplifier begins to shunt current away from the COMP pin. The rate of voltage rise on the COMP pin slows due to the decrease in total current out of the pin, decreasing the rate of duty cycle increase.
When the loop has reached the programmed limit the gm amplifier shunts the entire bias current ? A and the duty cycle remains fixed. If any of the control parameters tries to exceed the programmed limit, the gm amplifier shunts additional current from the COMP pin, further reducing the PWM duty cycle until the offending parameter is brought into check. The battery voltage is fed back to the gm amplifier through a resistor divider network. The precision voltage reference has a 0.
Tolerance resistors of 0. The voltage is converted to a current source that is used to develop a voltage drop across an internal offset resistor at one input of the SR gm amplifier. The charge current is then a function of this voltage drop and the sense resistor RS , refer to Figure 5. Programming the Adapter Current Like the battery charge current described previously, the adapter current is programmed via a voltage on the ACSET pin.
Steeper current slopes result in the converter operating in the discontinuous mode at a higher power level. Steeper current slopes also result in higher output ripple current, which may require a higher number or more expensive capacitors to filter the higher ripple current. In addition, the higher ripple current results in an error in the sensed battery current particularly at lower charging currents.
In this case, the inductor is usually much larger than necessary, which may result in an efficiency loss higher DCR and an area penalty. Selecting an Output Capacitor For this application the output capacitor is used primarily to shunt the output ripple current away from the battery.
Overshoot conditions can be observed at VCC line during fast load transients when the adapter powers the load or when the adapter is hot-plugged. Increasing the input capacitor value decreases the overshoot at VCC. Avoid overshoot voltages at VCC in excess of the absolute maximum ratings for that pin. A Type II compensation adds a pole-zero pair and an additional pole at dc.
To avoid adding secondary poles to the PWM closed loop system those filters should be set with cutoff frequencies higher than 1 kHz. This allows battery conditioning through smart battery learn cycles. NOTE: Selection of battery power whether manual or automatic results in the suspension of battery charging. An ACDET voltage less than the set threshold is considered as a loss of adapter power regardless of the actual voltage at the adapter input.
When switching between the ac adapter and battery the internal logic monitors the voltage at pins ACDRV and BATDRV to implement a break-before-make function, with typical dead time on the order of nsec. The adapter power can be reselected at the end of the learn cycle by a setting ACSEL to a logic high, provided that adapter power is present. Battery charging is suspended while selected as the system power source. NOTE: On the bq the ac adapter is switched to the load when the battery voltage reaches the battery depleted threshold; it can be used when the learn cycle does not require the battery voltage to go below the battery depleted threshold.
If the learn cycle algorithm requires the battery voltage to go lower than the battery depleted voltage, the bq should be used, as it does not switch the ac adapter to load upon battery depleted detection. To ensure that this happens under all load conditions, the system voltage load voltage can be monitored through a resistor divider on the VS pin.
If you are not familiar with lithium battery chargers I highly recommend you first read part 1 where I explain some of the fundamental concepts. One of the extra pins allows you to independently program the pre-charge and charge termination currents separately from the fast charge current. Another additional pin provides a status output indicating there is a sufficient input supply voltage present. Another pin monitors the battery temperature, and finally a fourth additional pin is a charge current override function for USB applications. Higher fast-charge current One of the big differences between the BQ and the MCP is the maximum charge current. With the BQ you can program the charge current between 10 mA and 1, mA. The charge current is set via resistor tied to the ISET pin.
Introduction to Battery Chargers (Part 2 of 2)
Learn More — opens in a new window or tab. Minimum monthly payments are required. Learn More — opens in a new window or tab Any international shipping is bq in part to Pitney Bowes Inc. Image not available Photos not available bq this variation Stock photo. Covers your purchase bq and original shipping. Both topologies reduce the battery char Doc. This item will ship to United Statesbut the seller has not specified shipping bq
BQ24703 DATASHEET PDF
Claim or contact us about this channel. Power management Below is the words on the datasheet. Chip enable pin of BQA. This is achieved by dynamically adjusting the battery charge current based on the total system adapter current. I did just finish charging 3 hours ago, I will let it rest for 24 hours more. Add to watch list. Many battery packs have an integrated protector so this may not be an issue.