1. Product Overview.
The APS4054 is a single-cell Li-ion battery constant current constant voltage linear charger with a simple external application circuit that is ideal for portable device applications, suitable for USB power supply and adapter power supply operation, with an internal anti-reverse charging path and no need for an external isolation diode. Thermal feedback automatically adjusts the charge current to limit the chip temperature during high-power operation or at high ambient temperatures. The APS4054 charge cut-off voltage is 42V, the charging current can be set by an external resistor. When the charging current drops to 1 10 of the set value, the APS4054 will automatically end the charging process. When the input voltage is removed, the APS4054 automatically enters a low-current standby state, reducing the standby current to less than 1UA. The APS4054 can also be placed in shutdown mode when there is input power, reducing the operating current to 30UA.
Second, product characteristics.
1. Pre-charge voltage: 42v±1%。Maximum charging current: 500mA.
9V trickle charge threshold.
3. Standby current 30ua. BAT ultra-low self-consumption 1UA.
4. Separate charging and end indicator control signals.
5. The intelligent thermal adjustment function can maximize the charging rate.
6. C 10 charging termination. Smart recharge function.
7. No MOSFET, sense resistor or or isolation diode required.
8. Package form: SOT23-5L.
3. Internal block diagram.
4. Package and pin function description.
aps4054,sot23-5l
1. CHRG: charging status indication end.
When the charger is charging the battery, the CHRG pin is pulled low by an internal switch, indicating that charging is in progress;When charging ends, the CHRG pull-down current becomes 20UA;When the VCC input voltage is below the undervoltage lockout threshold or the voltage difference between the VCC and BAT pins is less than 30mV, the CHRG pin is in a high-impedance state.
2. GND: power ground.
3. BAT: The battery is connected to the end.
Connect the positive end of the battery to this pin. When the chip is disabled to work or sleep mode, the leakage current of the bat pin is less than 2ua, and the bat pin provides charging current to the battery and 42V limiting voltage.
4. VCC: positive end of input voltage.
The voltage of this pin is the operating power supply for the internal circuit. The VCC input voltage must be greater than the undervoltage lockout threshold and both greater than the BAT voltage by 100mV for charging to begin. When the VCC input voltage is below the undervoltage lockout threshold or the voltage difference between the VCC and the BAT pin is less than 30mV, the APS4054 will enter a low-power shutdown mode where the current consumption of the BAT pin is less than 2UA.
5. PROG: constant current charging current setting terminal.
Connecting a resistor from the PROG pin to GND allows the charging current to be set. The setting resistor and charge current are calculated using the following formula:
RPROG = 1000V IBAT determines the resistance of the resistor RPROG based on the required charging current Ibat. During the trickle charging phase, the voltage of this pin is modulated at 01v；During the constant current charging phase, the voltage of this pin is fixed at 1V.
5. Refer to the application circuit diagram.
6. Electrical characteristics.
1. Electrical parameters (no special instructions, vin=12v, ta=25).
Note: Typical parameter values are standard parameter values measured at 25 conditions.
2. Limit parameters.
Note: The maximum limit value means that the chip may be damaged outside of this operating range.
7. Working principle.
The APS4054 is a linear charger specially designed for a Li-ion battery or Li-polymer battery, the chip integrates a power transistor, the charging current can be set with an external resistor, the maximum continuous charging current can reach 500mA, no additional resistance diode and current sense resistor are required. The APS4054 includes a status indicator for an open-drain output to indicate that charging is in progress or charging is complete. When charging, the pin CHRG output is low, indicating that charging is in progress, and after charging is completed, the CHRG pull-down current becomes 20UA.
If the battery voltage is lower than 29V, APS4054 pre-charges the battery with a small current. When the battery voltage exceeds 2At 9V, the battery is charged in constant current mode, and the charging current is determined by the resistor RPROG between the PROG pin and GND. When the battery voltage is close to 4When the voltage is 2V, the charging current gradually decreases, and the APS4054 enters the constant voltage charging mode. When the charging current decreases to the charging end threshold, the charging cycle ends, and the CHRG terminal changes from a strong current pulldown to a 20uA weak current pulldown. The end-of-charge threshold is 10% of the constant current charge current.
When the battery voltage drops to a recharge threshold of 4When it is below 1V, the APS4054 automatically starts a new charging cycle. The high-precision voltage reference, error amplifier and resistor divider network inside the chip ensure that the accuracy of the modulation voltage at the battery end is within 1%, which meets the requirements of lithium-ion batteries and lithium-polymer batteries. When the input voltage is lower than the undervoltage lockout threshold voltage or the input voltage is lower than the battery voltage, the charger enters a low-power sleep mode where the current drawn on the battery side is less than 2ua.
The intelligent temperature control circuit inside the APS4054 automatically reduces the charging current when the junction temperature of the chip exceeds 115, which allows users to maximize the power handling power of the chip without worrying about damage to the chip or external components due to overheating. In this way, the user can design the charge current without considering the worst-case scenario, but only according to the typical situation, because in the worst-case scenario, the APS4054 will automatically reduce the charging current.
8. Application Notes.
1. Charging termination.
The charging process ends when the charging current drops to 1 10 of the set value after the final float voltage is reached. This condition is detected by monitoring the PROG pin with an internal filtered comparator, and charging terminates when the PROG pin voltage drops below 100mV for more than 2ms. The APS4054 goes into standby mode, at which point the input supply current drops to 30 A.
2. Intelligent recharging.
In standby mode, the APS4054 monitors the BAT pin voltage only if the BAT pin voltage falls below the recharge threshold voltage of 4When 1V (corresponding to 80% 90% of the battery capacity), a new charging cycle will be started and the battery will be recharged, which avoids unnecessary repeated charging of the battery and effectively prolongs the service life of the battery.
3. Increase thermal regulation resistance.
Reducing the voltage drop between the VCC and BAT terminals of the IC can significantly reduce the consumption in the IC. This has the effect of increasing the charging current when thermally conditioning. This can be achieved by connecting a 0 in series between the input power supply and the VCC3 The power resistance or forward conduction voltage drop is less than 05V diode, thus dissipating some of the power.
4. Charging current soft start.
The APS4054 has a built-in soft-start circuit. When a charge cycle is initiated, the charging current will gradually rise from zero to a constant current charging current in a time of 20us.
5. Charging status indicator.
CHRG is the output terminal of open drain status indication, and CHRG has three status indications: strong current pulldown (about 10mA), weak current pulldown (20UA), and high impedance state. When the charger is in the charging state, the CHRG is forcibly pulled to a low level, and after the charging is over, the CHRG pull-down current becomes 20UA, and when the VCC input voltage is lower than the undervoltage lockout threshold or the voltage difference between the VCC and BAT pins is less than 30mV, the CHRG pin is in a high-impedance state. When the status indication function is not in use, the CHRG is floated or grounded.
6. Intelligent temperature control.
The APS4054 has an integrated intelligent temperature control function that automatically reduces the charging current when the chip temperature is higher than 115. This feature allows the user to increase the upper limit of the power handling capacity of a given board without the risk of damaging the APS4054. The charging current can be set based on the typical, not worst-case, ambient temperature, provided that the charger will automatically reduce the current under worst-case conditions.
7. Manual shutdown.
If the PROG pin is floated, the APS4054 is put into shutdown mode. The battery leakage current will drop to less than 1 A, and the supply current will drop to less than 30 A.
9. Packaging, SOT23-5L
10. Attention.