Features

Small 3-mm × 3-mm mlp (qfn) packaging

-POL Space Co., Ltd. Application

Integrated power field effect tube and current sensor, for charging applications up to 1-a

reverse leakage protection prevent battery Discharge

Integrated current voltage adjustment

± 0.5%pressure regulating accuracy

]

Pre -charging adjustment with a safety timer

LED or system interface status output indicator charging and failure status

battery insertion Remove the detection

cooperation with the controlled and uncontrolled supply

short circuit protection

charging voltage option: 4.2 v and 4.36 v

Application

Mobile phone

pda system

MP3 player [123 123 ]

Digital camera

Internet device

Explanation

bqtiny #8482; Linear charge management equipment, for portable applications with limited space. bqtiny #8482; series provides integrated power field effect tube and current sensor, reverse atresia protection, high -precision current and voltage adjustment, charging status, charging terminal, in a small package.

bqtiny #8482; three -phase charging of batteries: adjustment, constant current and constant voltage. Terminal charging according to the minimum current. The internal charging timer provides spare safety functions for charging. bqtiny #8482; if the battery voltage is lower than the internal threshold, it will automatically start charging. Bqtiny #8482; VCC power supply automatically enters the sleep mode when it is disconnected.

In addition to standard functions, different versions of BQTINY #8482; provide many additional functions. These include the temperature sensing input for detecting the thermal battery pack or the cold battery pack; the power supply that exists in the instructions that the power supply is good (PG) output; The input of the input of the fast charging timer and the TTL level timer and the terminal (TTE) for disable or enable the fast charging timer and charging.

Equipment information

function box diagram

Function function Description

bqtiny #8482; supports precision lithium ionization charging system suitable for single batteries. Figure 2 shows a typical charge distribution and application circuit. Figure 5 shows the operation flowchart.

Temperature appraisal

Note: The temperature limit is only applicable to the temperature sensing input (TS) quotation (TS) quotation Editions of foot options (BQ24020 and

BQ24014 ).

The version of the BQTINY has a TS tube foot option, which continuously monitors the battery temperature by measuring the voltage between the TS and the VSS tube foot. The negative temperature coefficient thermistor (NTC) and external compressor usually generate the voltage (see Figure 3). BQTINY compares the voltage with the internal V (TS1) and V (TS2) threshold to determine whether it is allowed to charge (see Figure 6). Because the external pressure and internal threshold are proportional to the VCC, the temperature sensing circuit is immune to any fluctuations in VCC.

Once the temperature of the threshold of V (TS1) and V (TS2) was detected, BQTINY immediately paused charging. BQTINY is stopped by closing the power field effect tube and maintaining a timer value (that is, the timer does not reset). When the temperature returns to the typical range, charging recovery.

The resistance values of RT1 and RT2 are calculated by formula 1 and type 2 (for NTC thermistor).

In type, RTC is a low -temperature resistance of thermistor, and RTH is the high temperature resistance of thermistor specified by thermistor manufacturers.

If you only need a temperature (heat or cold) settings, you can omit RT1 or RT2. Applying the constant voltage between VTS1 and VTS2 thresholds to the pin TS will disable the temperature sensing function.

Battery pre -adjustment

During the charging cycle, if the battery voltage is lower than the V (low V) threshold, BQTINY will apply a pre -charged current IO (Prechg) to the battery. This feature resurrected deeply discharged cells. The resistance RSET connected between Iset and VSS determines the pre -charging rate. V (prechg) and K (set) parameters are specified in the specification table.

BQTINY starts a safety timer T (Prechg) during the adjustment phase. If the V (low V) threshold is not reached during the timer cycle, BQTINY will turn off the charger andAT1 and STAT2 pins send fault signals. For more details, see the timer failure recovery part.

Battery charging current

BQTINY provides an internal current adjustment of programmable settings. The resistance between Iset and VSS, the resistance between RSET determines the charging ratio. V (set) and K (set) parameters are specified in the specification table.

Battery voltage adjustment

Voltage adjustment feedback was completed through BAT pins. The input is directly connected to the positive side of the battery pack. BQTINY monitor the voltage between battery packs in battery and VSS pins. When the battery voltage rises to the VO (REG) threshold, the voltage adjustment stage begins, and the charging current begins to gradually decrease.

As a safe backup, BQTINY also monitors the charging time in the charging mode. If it is not terminated during this time, T (CHG), BQTINY off the charger, and announce the failure on the STAT1 and STAT1 pin. For more details, see the timer failure recovery part.

Charging cone detection, termination and charging

BQTINY monitor the charging current during the voltage adjustment phase. Once the tapered threshold I (taper) is detected, the BQTINY startup tapered timer T (tossed). The charges are terminated after the timer expires. The resistance between Iset and VSS, the connected resistance between RSET determines the level of taper detection. V (cone) and K (settings) parameters are specified in the specification table.

If the charging current returns to the cone -shaped threshold I (cone), BQTINY will reset the cone timer.

In addition to the tapered current detection, BQTINY terminates the charge when the charge current is lower than the I (item) threshold. This function allows fast recognition batteries to remove or insert a full -length battery. Note that the cone timer is not used for I (item) detection. The resistance between Iset and VSS, the connected resistance between RSET determines the level of taper detection. V (item) and K (set) parameters are specified in the specification table.

After the charging is over, once the voltage on the battery pin is lower than the V (RCH) threshold, BQTINY will start charging again. This function keeps the battery full of capacity. For more details, see the battery deficiency detection part.

Sleep mode

If VCC is removed from the circuit (PG PIN is high impedance), BQTINY enters low -power sleep mode. This function prevents battery power from exhausted without VCC. When the sleep mode or VCC lt; VPOR and defaults to turn off the state, the state tube foot does not work.

Charging status output

The opening of the road set1 and STAT2 output indicates the operation of various chargers shown in the table below. These states can be used to drive LEDs or communicate with host processors. Note that the shutdown indicates that the open -circuit collector transistor has been closed. When VCC LT; VBAT (Sleep Mode – PG is closed), the STAT tube foot defaults to the state. Note that the STAT1 or STAT2 closed/off state is shared by multiple operating conditions. Decoder the actual failure state by monitoring in, BAT, PG, and TS.

PG output

When the road collector PG (good power) indicates when the AC adapter (ie VCC) exists. When a valid VCC is detected, the PG bipolar transistor is opened. This output is closed in the sleep mode. PG pins can be used to drive LEDs or communicate with host processors.

CE input (charging enable)

CE digital input is used to disable or enable the charging process. The low -level signal on this pin is enabled and charged, and the high level signal is disabled for charging. The high-low conversion on this pin will also reset all the timers and fault conditions, and start a new charging cycle.

TTE input (timer and terminal enable)

TTE digital input is used to disable or enable fast charging timers and charging. The low -level signal on this pin enables fast charging timer and terminals, while high -level signals disable this function. The high-low conversion on this tube will also reset all the timers.

Hot stacking and protection

The connection temperature TJ of the bqtiny monitoring mold, if TJ exceeds 155 ° C, is suspended to charging. When TJ drops to about 130 ° C, charging recovers.

No battery detection

For applications with a mobile battery pack, BQTINY provides a battery -free detection solution to detect or remove the battery pack, or both And there.

After fast charging, the charging battery keeps the voltage on the battery pins higher than the battery charging threshold V (RCH). When the voltage of the battery pins drops to the charging threshold, whether it is due to the battery load or due to the disassembly of the battery, BQTINY starts the battery deficiency detection test. The test includes the test current I (detection) continuously T (detection) and check whether the battery voltage is lower than the pre -charging threshold V (low voltage). Subsequently, the pre -charging current IO (prechg) was applied for a period of time T (detection), and check whether the battery voltage is higher than the charging threshold. The purpose is to try to close the protection of a battery pack and open, if a connection to BQTINY. The discharge and charging test shows that there are battery deficiency failures on the STAT pin. Any test failure will start a new charging cycle. For the lack of batteries, the voltage on the battery pin is V (low voltage) and VO (adjustment) thresholdRising and declined indefinitely. See Figure 7.

timer failure recovery

As shown in Figure 5, BQTINY provides a recovery method for processing timer failure. The following conditions summarize this method.

Condition 1: The charging voltage is higher than the charging threshold (V (RCH)) and the timeout failure occurs

recovery method: Bqtiny waits for the battery voltage to fall below the charging threshold. This may be caused by battery load, self -discharge, or disassembling battery. Once the battery is lower than the charging threshold, BQTINY will clear the fault and enter the battery missing detection program. The POR or CE switch can also clear the failure.

Condition 2: The charging voltage is lower than the charging threshold (V (RCH)) and the timeout failure occurs.

Recovery method: In this case, BQTINY application i (fault) current. This small current is used to detect the disassembly of the battery, and keep connecting when the battery voltage is kept below the charging threshold. If the battery voltage is higher than the charging threshold, BQTINY will disable the recovery method described by the I (fault) current and perform conditions 1. Once the battery is lower than the charging threshold, BQTINY will clear the fault and enter the battery missing detection program. The POR or CE switch can also clear the failure.

Application information

Select the input capacitor

In most applications, only a high -frequency decoupling capacitor is required. A 0.47-μF ceramic is placed near VCC and VSS pins, and the effect is very good. BQTINY design is used to regulate and non -regulating external DC power supply. If the non -regulating power supply is selected, the power unit should have sufficient capacitors to keep the power supply voltage at the required minimum input voltage under the maximum load. Otherwise, more capacitors must be added to the input end of the charger.

Selecting output capacitors

BQTINY only needs a small output capacitor to ensure the stability of the ring. A 0.1 μF ceramic capacitor is placed between the battery and the ISET pin. For applications with detachable battery packs, 1 μF ceramic capacitors can ensure the normal operation of the battery detection circuit. Note that the output capacitor can also be placed between BAT and VSS pin.

Thermal factors

BQTINY packaged in the heat enhancement MLP (also known as QFN) packaging. The package includes hot pads to provide effective thermal contact between equipment and printing circuit boards (PCB). QFN/SON PCB Annexes Application Description (SLUA271) provides a complete PCB design guide for the package.

The most commonly used method for measuring packaging thermal performance is to measure (or simulation) from the device connection to the air around the packaging surfaceGas (environment) thermal impedance (θJa). The mathematical expression of θja is:

in the formula:

tj device knot temperature

ta ambient temperature

[ 123] P Equipment power consumption

The factors that have a large impact on the measurement and calculation of θja are:

Whether the device is installed on the board

#8226; trace size, ingredients, thickness and geometric shapes

Equipment direction (horizontal or vertical)

123]

Whether the other surfaces are close to the measured device

Device power consumption P is a function of the charge rate and internal power field effect tube drop. Can be calculated by the following equations:

Due to the charging characteristics of the lithium XX battery, when the battery voltage is at the lowest value, the maximum power consumption usually appears at the beginning of the charging cycle. See Figure 2.

Precautions for PCB layout

Special attention to the layout of the printing circuit board is very important. The following list provides some guidance principles:

In order to obtain the best performance, the output filter capacitors from VCC to VSS and BAT to ISET should be as close to BQTINY, signals and VSS tube feet as possible as possible. Both should run short distances.

All low -current VSS connections should be separated from the high current charging or discharge circuit of the battery. Use a single -point grounding technology that also includes a small signal grounding path and a power grounding path.

BAT pins are the voltage feedback of the device, and should be connected as close to the trajectory as close to its trajectory as much as possible.

The large current charging circuit diameter of the entry and exit foot must be suitable for the maximum charging current to avoid the voltage in these paths from decreased.

bqtiny packaged in thermal enhancement MLP packaging. The package includes hot pads to provide effective thermal contact between equipment and printing circuit boards (PCB). The design guidelines for the complete printing circuit board of this packaging are shown in the application instructions, the title is: QFN/SON printing circuit board attachment application instructions (SLUA271).

The exposed thermal pads and the VSS pins of the device have internal electrical connections. The exposed hot pads must be connected to the same potential as the VSS pin on the printing circuit board. Do not use the hot pad as the main place of the device. The speed of the speed sensor must always be grounded.

Packaging material information