Features

Charging

-1%Charging voltage accuracy

-The charging accuracy 10%

- pinch is available for choice. USB 100MA and 500MA maximum input current limit

- programmable terminal and pre -charging threshold, BQ24040

Protection

─ 30v input Rickter value; with 6.6V or 7.1V input overvoltage protection

-The input voltage dynamic power management

-125 ° C thermal regulation; 150 ° C heat shutdown protection

- Short -circuit protection and ISET short -circuit detection

-In the battery NTC running within the Jeita range -1/2 fast charging current when the cold state, 4.06V under the hot state, BQ24040

- Fixed 10 hours of fixed 10 hours Safety timer

System

- Automatic termination and timer disable mode (TTDM), suitable for battery packs with armistor, BQ24040

- Status indication-charging/completion

-This provides 2 × 2mm2 DFN-10 small packaging

-The integrated production line test automatic startup function, bq24041

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123] Explanation

The BQ2404X series equipment is a highly integrated lithium ion linear charger device, which is a portable application with limited space. These devices work through the USB port or AC adapter. Highly input voltage range with input overvoltage protection supports low -cost no -regulatory adapter.

BQ2404X has a single power output to charge the battery. As long as the average system load cannot prevent the battery from being fully charged during a 10 -hour safety timer, the system load can be connected in parallel with the battery.

The battery is charged in three stages: adjustment, constant current and constant voltage. In all charging stages, the internal control loop monitoring IC knot temperature and reducing the charging current when exceeding the internal temperature threshold.

The power level and charging current detection function of the charger is completely integrated. The charger function has high -precision current and voltage adjustment circuit, charging state display and charging termination. Pre -charging current and terminal current threshold are programmed by external resistors on the BQ24040. The fast charging current value can also be programmed by external resistors.

Order information

Typical application circuit: BQ24041

ouut_fast_chg 540 mAh; iOUT_PRE_CHG 108 mAh; iOUT_ item 54 mm install.

Typical application circuit: BQ24041, with ASI and ASO

iOUT_FAST_CHG 540 mAh; IOUT_PRE_CHG 108 mAh; IOUT_ item 54 mia Essence

Figure Figure

Typical operating characteristics

Settings: BQ24040 typical application diagram; vin 5V, VBAT 3.6V (unless otherwise explained).

上电、断电、OVP、禁用和启用波形

[123 ]

Protecting circuit waveform

Function 2 × 2 single battery lithium ion charger family. The charger can be used to charge the battery, supply the system, or both. There are three stages of charging at the charger: pre -charging to restore the battery that is completely discharged, and quickly charging constant current to safely provide antihypertensive charging and voltage adjustment to safely achieve a full capacity. The charger is very flexible, allowing fast charging current and pre -charging/termination current (only BQ24040). This charger is designed for USB connection or adapter (DC-OUT). The charger will also check whether there is a battery.

The charger is also equipped with a full set of safety functions: Jeita temperature standards (only BQ24040), overvoltage protection, DPM-in, security timer and ISET short circuit protection. The following will describe all these characteristics and more features in detail.

The charger is designed as a single power path from input to output to charge a single battery lithium -ion battery pack. After applying a 5VDC power supply, ISET and OUT short -circuit checks will be performed to ensure the correct charging cycle.

If the battery voltage is lower than the low voltage threshold, it is considered that the battery has been discharged and the preprocessing cycle is started. The quantity of the pre -charging current can be programmed using a pre -charged pin. The pins will program the percentage of the fast charging current (10%to 100%) as a pre -charged current. This function is very useful when the system load is connected to the battery current through the battery. Pre -charging current can be set higher to adapt to the systemLoad, at the same time, the battery is adjusted appropriately. Pre -charging pin is a dual -function pin, which is used to set up a pre -charged current level and terminal threshold level. Terminal current threshold is always half of the current of pre -charged programming current.

Once the battery voltage is charged to the VlowV threshold, the fast charging starts and applies fast charging current. Use the ISET pin to program to quickly charge the constant current. Hengliu provides most of the charge. Under fast charging and lower battery voltage, IC consumption is the greatest power. If the IC reaches 125 ° C, the IC enters the heat -tone, reduce the timer clock by half, and reduce the charging current as needed to prevent further temperature. Figure 23 shows the charging curve with hot adjustment. Under normal working conditions, the knot temperature of the integrated circuit is lower than 125 ° C, and no heat is performed.

Once the battery charges to the adjustment voltage, the voltage circuit begins to control, and keeps the battery in the adjustment voltage until the current gradually decreases to the termination threshold. If necessary, the terminal can be disabled. The CHG pin is low (LED lit) in the first charging cycle. Once the termination threshold is reached, the pin will be extinguished, regardless of whether the terminal of the charging current is enabled or disabled.

More details are mentioned in the first section of the operation mode.

Detailed function description

Power off or under voltage lock (UVLO)

If the internal voltage of the pin is lower than UVLO, then BQ2404X The series is in the power off mode. This part is considered to be dead and all pins is high impedance. Once the input voltage is higher than the UVLO threshold, IC will enter the dormant mode or activation mode according to the output pin (battery) voltage.

Powering

After the input voltage is higher than UVLO (see the dormant mode), the IC is in a state of activity, reset all logic and timers, and starts to perform many continuous monitoring routine procedures. Under normal circumstances, in the case of 100MISG input, the voltage of the input terminal will rise quickly, so that the voltage of the input terminal will rise rapidly. See Figure 24.

Sleep mode

If the IN pin voltage is between Vout+VDT and UVLO, the charging current is banned, the safe timer counts to stop (not reset), PG and CHG pin impedance high impedance impedance high Essence When the input voltage increases and the charger exits the dormant mode, the PG pin becomes lower, the safe timer continues to count, the charging is enabled, and the CHG pin returns to the previous state. See Figure 25.

New charging cycle

When a good power supply is applied, execute chip disable/enabled (ts pin/bat_en), exit terminal and timer disable mode (TTDM), and detect battery insertion. Or when the output voltage is lower than the VRCH threshold, the new charging cycle begins. CHG pin is only in a low level activation state in the first charging cycle, soIf the CHG pin is already highly impedance, the voltage that exit TTDM or lower than VRCH will not open the CHG pin FET.

Overvoltage protection (OVP) - Continuous monitoring

If the input source applies overvoltage, then pass fET (if it was previously opened) is divided by division) Turn off after crystal TBLK (OVP). After the timer is over, CHG and PG pins enter a high impedance state. Once the overvoltage is returned to normal voltage, the PG pin becomes lower, the timer continues to work, the charging continues, and the CHG pin becomes lower after 25ms removing ice. PG pins are available on some packaging.

Good power instructions (PG)

After applying 5V power supply, the input voltage increases to UVLO and dormant threshold (VIN u0026 GT; VBAT+VDT), but lower than OVP (vin u0026 lt; vovp), Then PG FET is turned on and provides a low impedance grounding path. See Figure 5, Figure 6, and Figure 18.

Change pins instructions

There is a internal opening of the drain field effect crystal of the charging pipe foot, which is only opened during the first charging (pulled down to VSS) (has nothing to do with TTDM), Once the battery reaches the voltage adjustment, the charging current is gradually reduced to the termination threshold set by the preliminary resistor, and it will be closed.

The charging pipe foot is high impedance under the dormant mode and OVP (if PG is high impedance), and returns to the previous state after the condition is eliminated.

The cycle input power supply, pull the TS pin low, release or enter the pre -charging mode, will cause the CHG pin to reset (if the power supply is good and connects the discharged battery, it becomes a low level). It is regarded as the beginning of the first charging.

CHG and PG LED pull -up power supply

For the monitoring of the host, use a pull -up resistor between the state pin and the VCC of the host. For visual indications, in the state A resistor connected to LED between the pin and the power supply. If the CHG or PG power supply can exceed 7V, 6.2V Zina should be used to restrain the voltage. If the power supply is an out pin, please note that as the battery voltage changes, the brightness of the LED will also change.

Automatic startup (BQ24041)

The automatic startup function is an or door with two inputs; VIN-DT is logic 1) and the external input from ASI pin (dropped from 100K inside). The ASO pin output can be used as a signal of the system to guide signal. The OUT pins are powered by the OUT pin. OUT pin must be powered by the external power supply (battery or P/S), or the ASO pin can be provided by the ASO pin to provide a logic high level. ASI and/or internal power supplyA good signal must be a logic high level, and ASO is the logic high level. ASI/ASO, OUT, and PG signals are used for production testing to test the battery -free system.

In-DPM (VIN-DPM or in-DPM)

In-DPM function is used to detect inputs (voltage decreased) and reached its current limit due voltage. When the input voltage drops to the VIN-DPM threshold, the endless effect transistor begins to reduce the current until the input voltage no longer decreases. This will prevent the voltage below VIN-DPM's power supply for OUT pin. The rated voltage of the rated voltage and the USB adapter of more than 4 volts is limited. This is an additional security characteristic that helps protect the power supply from overloaded.

OUT

The output pin of the charger provides a current to the battery and system (if.). The integrated circuit can be used to charge the battery and supply the system. Only the battery is charged or the system is only powered (TTDM). It is assumed that the load does not exceed the available current. The output pin is a current restriction source, which is inherently protected to prevent short circuit. If the system load exceeds the output programming current threshold, the output will be discharged, unless there is enough capacitor or a charging battery to supplement too much load.

ISET

The external resistor is used for programming output current (50 to 800mA), and can be used as a current monitor.

Among them: IOUT is the fast charging current required; KISET is the gain coefficient in the electrical specification.

In order to obtain higher accuracy at a lower current, some sensor field effect tubes were banned to provide better resolution. Figure 19 shows the transition from low -current to high current. From high current to low current, there is a lagging phenomenon, and it has changed around 0.15A.

The ISET resistor is protected by short circuit, and the resistance of less than 340 u0026#8486; The detection requires at least 80mA output current. If short circuit is detected, the IC will be closed and can only be reset through the circulating power supply. The output current is limited to the maximum current between 1.1A and 1.35A, and is independent of the ISET short -circuit detection circuit, as shown in Figure 27. Please refer to Figure 13 and Figure 14.

Pre-charging terminal-pre-charging and terminal programming threshold, BQ24040

Pre-Term for programming pre-charging current and termination current threshold threshold Essence Pre -charging current levels are twice as high as the terminal current. The terminal can be set between 5%and 50%of the programming output current setting set. If it is kept floating, the termination and pre -collection fees are set to 10/20%in the internal settings, respectively. Pre -charging to fast charging, vlowv threshold setPlace to 2.5V.

where:

The terminology is the percentage of fast charging current;

%pre chg is the pre -charged period The percentage of the required fast charging current;

KTERM and KPRE-CHG are the gain coefficients in electrical specifications.

Iset2

is a 3 state input, programming the input current limit/adjustment threshold. The low will be programmed by the ISET resistor to adjust the rapid charging current. It is the maximum allowed input/output current set by any ISET2 settings. The floating point will be a programming 100mA current limit.

The following is two configurations that drive 3 -state ISET2 pin:

TS (bq24040)

The design of the ts pin follow follows follow New Jeita temperature standard lithium ion battery. There are four thresholds now, 60 ° C, 45 ° C, 10 ° C and 0 ° C. Normal operation occurs between 10 ° C and 45 ° C. If between 0 ° C and 10 ° C, the charging current level will be reduced by half. If between 45 ° C and 60 ° C, the adjustment voltage will be reduced to the maximum value of 4.1V, as shown in Figure 26. The TS function is to use an internal 50 μA current source to connect to the thermistor of the vss from the TS pin to the VSS (designed for 10K NTCβ 3370 (Semi Tek 103AT-2 or Mitsubishi TH05-3H103F). You can place a fixed 10K between TS and VSS to allow normal operations. If the host is monitoring thermoltic resistance, and then the host will determine when the TS pin is pulled down to disable the charging, you can perform this operation. [123 123 ]

When the TS pin is low or floating/driving high, the TS pin has two additional functions. Low ban charging (similar to the high charging function on the battery), the high charger enters TTDM. [123 123. ]

higher than 60 ° C or below 0 ° C, charging is stopped. Once the thermal resistance reaches -10 ° C, the TS current will be folded back to prevent the hot and cold resistance (from -10 ° C and- 50 ° C) Place the IC in the TTDM mode. If the TS pin is pulled down to the disable mode, the current will be reduced to 30 μA, as shown in Figure 24. Since the ITS current and temperature threshold are fixed, except 10K NTC (25 25 (25 In addition to ° C), it is impossible to use thermistor resistance.

Terminal and timer disable mode (TTDM) -TS pins high

When removing the thermistor (removed the battery When a group/floating TS pin) or when the TS pin is pulled to the TTDM threshold, the battery charger is in TTDM.

When entering TTDM, it is safe for 10 hours.The timer is kept reset and the terminal is disabled. Run the battery detection program and check whether the battery has been removed. If the battery is removed, the CHG pin will enter a high impedance state (if not yet). If the battery is detected, the CHG pin will not change the state before the current is gradually reduced to the terminal threshold. If not yet, the CHG pin will enter a high impedance state (the adjustment output will be kept on).

The charging mode is unchanged (there are still pre -charging, fast charging constant current and constant voltage mode). This means that the battery is still safely charged, and the current can gradually decrease to zero.

When coming out of TTDM, the battery detection program will run. If the battery is detected, start a new charging cycle and light up the CHG LED.

If TTDM is not required when disassembling batteries with a thermistor, you can add 237K resistance between TS and VSS to disable TTDM. This can prevent the current source from driving the TS pin to TTDM. This generates a 0.1 ° C error under the heat, and a 3 ° C error is generated under the cold state.

timer

The pre -charged timer is set to 30 minutes. Pre -charging current can be programmed to offset any system load and ensure that 30 minutes are sufficient.

The fast charging timer is fixed at 10 hours, and it can increase in real time by entering thermal retention, IN-DPM or if it is limited by USB current. The timer clock will slow down at 2 times, resulting in half faster than the clocks in these modes. If the timeout of a 30 -minute or 10 -hour timer is ended, the charging is terminated. If it is not in this state, the CHG pin will become high impedance. The timer is reset by turning off IC, circulating power supply or entering and leaving TTDM.

Termination

Once the OUT pin is higher than VRCH (reaches voltage adjustment), the current gradually drops to the terminal threshold, the CHG pin will become high impedance, and the battery detection path will be run to determine Whether the battery has removed or the battery is full. If there is a battery, the charging current will be terminated. If the battery and thermistor are removed together, the TS pin is driven to high level and the charge enters TTDM. If the battery has been removed and the TS pin is kept in the activated area, the battery detection program will continue until the battery is inserted.

Battery detection program

The battery detection program should check whether the battery is missing, while maintaining the OUT pin in an available voltage. Whenever the battery is lost, the CHG pin should be high impedance.

The battery detection program runs when entering and exiting TTDM to verify whether the battery exists; if the battery is lacking and is not in TTDM, it will continue to run. When power is powered, if the battery voltage is greater than VRCH, the battery detection program is run to determine whether the battery exists.

When the IC is in TTDM or there is a TS failure, the battery detection program is disabled. The battery detection flowchart is shown in Figure 28.

Refresh the threshold

After termination, if the OUT pin voltage drops to VRCH (below the specified value of 100 millivolta), new charging will be activated, but the CHG pin remains high impedance (OFF To.

Start charging when fully charged

In the first minute of the charging cycle, the termination threshold increased by 14%. Therefore, if you remove and insert a complete battery or start a new charging In the cycle, the new charging will be terminated (less than 1 minute). The battery that has been relaxed for many hours may take a few minutes to gradually decrease to the termination threshold and terminate charging.

BQ24040 charger application design example

Requirement

power supply voltage 5 v

Quick charging current: IOUT-FC 540 ma; ISET pin 2

terminal current threshold:%iOut-FC fast charging 10 10 10 10 %Or ~ 54mA

Pre -charging current defaults to twice or ~ 108ma

TS -battery temperature sensing 10K NTC (103AT) [103AT) [103AT) [103AT) [103AT) [103AT) 123]

Calculate

Programming fast charging current, ISET:

Standex [K (ISET)/I (output)]

From the electrical characteristic table. K (settings) 540A u0026#8486;

Increasing pipe [540a u0026#8486; /0.54a] 1.0 k u0026#8486; Use 1.0 k u0026#8486; resistor between foot 16) and VSS.

Programming termination current threshold, ITERM:

rpre-term k (item) × iOUT-FC%

rpre-terminal 200 u0026#8486;/%× 10 % 2k u0026#8486;

Select the closest standard value, and use 2 K u0026#8486; resistors between ITERM (pin 15) and VSS.

Use 20%as a pre -charging value (2 times the difference coefficient) to get the same value.

RPRE-TERM K (Pre-change) × IOUT-FC%

rpre-terminal 100 u0026#8486;/%× 20% 2k u0026#8486;

TS function (BQ24040)

Use 10 in the battery pack (103AT) 10K NTC thermistor.

The temperature sensing function should be disabled, and a fixed 10K resistor is used between TS (pin 1) and VSS.

Change and pg

LED status: connect a 1.5k resistor with LED between the OUT pin and CHG pin. A 1.5K resistor with LED is connected between the OUT pin and the And PG pin.

Monitor surveillance: Connect a pull -up resistor between the power rail of the processor and the CHG pin. Connect a pull -up resistor between the power rail of the processor and the PG pin.

Selection of the input and output pins capacitors

In most applications, you only need to install a high -frequency decoupling capacitor (ceramic) on the power pins, input and output pin. It is recommended to use the value displayed on the application relationship diagram. After evaluating these voltage signals with the actual system operation conditions, you can determine whether the capacitance value can be adjusted to the minimum recommended value (DC load application) or higher value to use it for fast high -sharing pulse load applications. Note: If the design is designed for high input voltage source (adverse ornament or error adapter), the capacitor needs to be appropriately rated. The test value of ceramic capacitors is twice the rated value, so 16V capacitors may be sufficient to withstand a 30V transient voltage (the rated value of the test with the capacitor manufacturer).

Hot packaging

The BQ2405X series uses thermal enhanced MLP packaging. The package includes a hot pad to provide effective thermal contact between IC and printing circuit board (PCB). The power board should be directly connected to the VSS pin. The full PCB design guide of this packaging is shown in the title: QFN/SON PCB Anecium Application Instructions (SLUA271). The most common measurement method of packaging thermal performance is from chip to the heat impedance (θJa) from the chip to the surface (environment). The mathematical expression of θja is:

where:

tj chip knot temperature

t ambient temperature

] P Equipment power consumption

Factors that affect θja measurement and calculations include:

1. Whether the device is installed on the board

And geometric shape

3. Equipment direction (horizontal or vertical)

4. The volume and air flow of the environmental air around the measured equipment

5. Whether the other surfaces are close to the tested tested Equipment

Due to the charging mode of lithium ion batteries, the maximum power consumption usually appears at the minimum level when the charging cycle starts. Usually, after the fast charging starts, the battery pack voltage increases to 3.4 volts in the first 2 minutes. The hot time constant of the component usually takes a few minutes to addHeat, so when the maximum power consumption is calculated, 3.4V is a very minimum voltage. By drawing the temperature at the bottom of the PCB under the IC (the pads should have multiple pores), the charging current, and the curve of the battery voltage change over time, the system and a completely discharged battery are verified. If the parts enter the heat, the fast charging current will begin to decrease.

The power consumption P of the device is a function of the internal power field effect of the transistor's charge and voltage drop. When the battery pack is charged, calculate the following procedures:

The thermal circuit characteristics are reduced to reduce the charging current to limit the excessive IC knot temperature. It is recommended to use this function under typical operation conditions (nominal input voltage and nominal ambient temperature), and use this function under the atypical case of the hot environment or higher than the normal input power supply voltage. Having said that, if the hot circuit is always in a state of activity, IC will still work in the above way.

The impact of the leakage current on the battery capacity

To determine the leakage current on the battery, it is a simple calculation to discharge the battery discharge at a fast speed. From full to discharge time, you can use the battery ampere hour capacity to be calculated by leakage current. For 0.75AHR batteries and 10μA leak current (750mAhr/0.010mA 75000 hours), discharge takes 75K hours or 8.8 years. In fact, the self -discharge speed of the battery is much faster, so the leakage of 10μA is considered responsible.

Layout prompts

In order to obtain the best performance, the output filter capacitors from IN to GND and output filter capacitors from OUT to GND (thermal Pad) should be as close to BQ2405X as possible as possible And short tracking of IN, OUT and GND (Thermal Pad).

All low -current grounding connections should be separated from the high current charging or discharge circuit of the battery. Use single -point grounding technology, including small signal grounding paths and power grounding paths.

The size of the high -current charging load transition from the IN pin and the high current charging current from the OUT pin must be suitable for the maximum charging current to avoid voltage drops in these circuits.

BQ2405X series is encapsulated by thermal enhanced MLP. The package includes a hot pad to provide effective thermal contact between IC and printing circuit board (PCB); the hot pad is also the main connection of the device. Connect the hot pad to the PCB grounding connection. It is best to use 10 dense ear -vertical holes on the power board of the integrated circuit to transmit heat to the bottom ground floor. The bottom of the bottom should avoid the traces of cutting the heat path. The thinner the PCB, the smaller the warmth. The thickness of EVM PCB is 0.031 inches, and 2 ounces (2.8 mm thick) copper at the top and bottom are a good example of the best heat performance.