LTC4002ES8-8.4#TRPBF

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1. Describe

LTC®4002 is a complete battery charger controller for One (4.2V) or two (8.4V) lithium-ion batteries. Use one 500kHz switching frequency, LTC4002ES8-8.4#TRPBF provides a Small, simple and efficient lithium-ion fast charging solution Batteries from various power supply voltages. An external The sense resistor sets the charging current with an accuracy of ±5%. An internal resistor divider and precision reference setting The final float voltage of each battery is 4.2V, and the accuracy is ±1%. When the input power is removed, the LTC4002 automatically enters a low-current sleep mode, thereby reducing battery power The leakage current is 10µA. Internal comparator detection When the internal timer is set, the end of charge condition is approaching The total charging time and the termination of the charging cycle. Rear At the end of the charging cycle, if the battery voltage is lower than Each battery is 4.05V, and a new charging cycle will start automatically. LTC4002 uses 8-lead SO and 10-lead DFN Bag.

2. Feature

    1. Wide input power range:

        - 4.7V to 22V-4.2 version

        - 8.9V to 22V-version 8.4

    2. High-efficiency current mode PWM controller with 500kHz switching frequency

    3. ±1% charging voltage accuracy

    4. Charge end current detection output

    5. 3 hours charge termination timer

    6. Constant switching frequency for minimum noise

    7. ±5% charge current accuracy

    8. Low 10µA reverse battery leakage current

    9. Automatic battery charging

  10. Automatically shut down when the input power is removed

  11. Low-voltage battery automatic trickle charging

  12. Battery temperature sensing and charging certification

  13. Stable ceramic output capacitor

  14. 8-pin SO and 10-pin DFN packages

3. Application

    1. Portable computer

    2. Charging stand

    3. Handheld instrument

4. Pin configuration

5. Pin function

  1. COMP (Pin 1/Pin 1): Compensation, Soft-Start and Shutdown Control Pin. The COMP pin is the control signal of the inner loop of the current mode PWM. Charging begins when the COMP pin reaches 800mV. The recommended compensation components are a 0.47µF (or larger) capacitor and a 2.2k series resistor. A 100µA current into the compensation capacitor also sets the soft-start slew rate. Pulling the COMP pin below 360mV will shut down the charger.

  2. VCC (Pin 2/Pin 2): Positive Supply Voltage Input. VCC can range from VBAT(FLT) + 0.5V to 22V. A 0.1µF or higher capacitor is required at the VCC pin with the lead length kept to a minimum. A 10µF low ESR capacitor is also required at the source pins of the power P-channel MOSFET.

  3. GATE (Pin 3/Pin 3): Gate Drive Output. Driver Output for the P-Channel MOSFET. The voltage at this pin is internally clamped to 8V below VCC, allowing a low voltage MOSFET with gate-to-source breakdown voltage of 8V or less to be used.

  4. PGND, SGND, Exposed Pad, GND (Pins 4, 5, 11/Pin 4): IC Ground. The exposed pad (DFN) must be soldered to PCB ground to provide both electrical contact and optimum thermal performance.

  5. CHRG (Pin 6/Pin 5): Open-Drain Charge Status Output. When the battery is being charged, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge current drops below the End-of-Charge threshold for more than 120µs, the N-channel MOSFET turns off and a 25µA current source is connected from the CHRG pin to GND. When the timer runs out or the input supply is removed, the 25µA current source is turned off and the CHRG pin becomes high impedance.

  6. BAT (Pin 7/Pin 6): Battery Sense Input. A bypass capacitor of 22µF is required to minimize ripple voltage. An internal resistor divider, which is disconnected in sleep mode, sets the final float voltage at this pin. If the battery connection is opened when charging, an overvoltage circuit will limit the charger output voltage to 10% above the programmed float voltage. When VBAT is within 250mV of VCC, the LTC4002 is forced into sleep mode, dropping ICC to 10µA.

  7. SENSE (Pin 8/Pin 7): Current Amplifier Sense Input. A sense resistor, RSENSE, must be connected between the SENSE and BAT pins. The maximum charge current is equal to 100mV/RSENSE.

  8. NTC (Pin 9/Pin 8): NTC (Negative Temperature Coefficient) Thermistor Input. With an external 10kΩ NTC thermistor to ground, this pin senses the temperature of the battery pack and stops the charger when the temperature is out of range. When the voltage at this pin drops below 355mV at hot temperature or rises above 2.465V at cold temperature, charging is suspended and the internal timer stops. The CHRG pin output is not affected during this hold state. To disable the temperature qualification function, ground the NTC pin.

  9. NC (Pin 10/NA): No Connect.

6. operate

LTC4002 is a constant current, constant voltage Li-ion battery charger controller using current mode PWM buck (buck) switch architecture. cost The current is set by the external sense resistor (RSENSE) Across the SENSE and BAT pins. The last battery float The voltage is set internally to 4.2V per battery. For batteries, such as Li-ion batteries that require accurate final float voltage, The internal 2.465V reference, voltage amplifier and resistor divider provide ±1% accuracy adjustment. When the voltage on the VCC pin rises, a charging cycle begins Above the UVLO level and greater than or equal to 250mV battery voltage. At the beginning of the charging cycle, If the battery voltage is lower than the trickle charge threshold, the 4.2 version is 2.9V, and the 8.4 version is 5V, the charger enters the trickle charge mode. Trickle charge The current is internally set to 10% of the full-scale current. if The battery voltage is low for 30 minutes, the battery It is considered to be faulty and the charging cycle is terminated. When the battery voltage exceeds the trickle charge threshold, the charger enters a full-scale constant current Charging mode. In the constant current mode, the charging current is determined by the external sense resistor RSENSE and a Internal 100mV reference; IBAT = 100mV/RSENSE. When the battery voltage is close to the set value Floating voltage, the charging current will start to drop. When the current drops to 25% (version 4.2) or 10% (8.4 Version) full-scale charge current, the internal comparator turns off the internal pull-down N-channel MOSFET At the CHRG pin and connect the weak current source to Grounding indicates that charging is about to end. An internal 3-hour timer determines the total charging time. After a timeout occurs, the charging cycle is terminated And the CHRG pin is forced to be high impedance. Reboot Charge cycle, remove and reapply input voltage or Turn off the charger temporarily. In addition, the new charge If the battery voltage is lower than The charging threshold voltage of each battery is 4.05V. When the input voltage is present, the charger can be turned off Reduce by pulling the COMP pin low (ICC = 3mA). when. . . when The input voltage does not exist, the charger enters the sleep state