LTC4120/LTC4120-4.2 PIN FUNCTIONS where hPROG is typically 988. Keep parasitic capacitance as IN when disabled, and can sink currents up to 5mA on the PROG pin to a minimum. when enabled. An NTC temperature fault causes this pin CHRG (Pin 14): Open-Drain Charge Status Output Pin. to be pulled low. A bad battery fault also causes this pin Typically pulled up through a resistor to a reference volt- to be pulled low. If no fault conditions exist, the FAULT age, the CHRG pin indicates the status of the battery char- pin remains high impedance. ger. The pin can be pulled up to voltages as high as IN RUN (Pin 16): Run Pin. When RUN is pulled below VEN when disabled, and can sink currents up to 5mA when and its hysteresis, the device is disabled. In disabled enabled. When the battery is being charged, the CHRG mode, battery charge current is zero and the CHRG and pin is pulled low. When the termination timer expires or FAULT pins assume high impedance states. If the voltage the charge current drops below 10% of the programmed at RUN is pulled below VSD, the device is in shutdown value, the CHRG pin is forced to a high impedance state. mode. When the voltage at the RUN pin rises above VEN, FAULT (Pin 15): Open-Drain Fault Status Output Pin. the INTVCC LDO turns on. When the INTVCC LDO rises Typically pulled up through a resistor to a reference volt- above its UVLO threshold the charger is enabled. The age, this status pin indicates fault conditions during a RUN pin should be tied to a resistive divider from VIN to charge cycle. The pin can be pulled up to voltages as high program the input voltage at which charging is enabled. Do not float the RUN pin. BLOCK DIAGRAM C2S LTC4120 ENABLE IN INTV LDO CC 3 1 CINTVCC RUN INTV 2.2µF CC 16 + ENABLE BOOST C 2 IN 10µF 2.45V – CBST C2P + 22nF PWM SW INTV 0.9V CC 4 – • SHUTDOWN L BAT + R LSW DUVLO GND IN – 80mV – 5 33µH INTVCC CHGSNS V DHC IN(DHC) + 8 6 DHC R IN SNS – 0.3Ω IN FREQ I BAT TH C-EA 9 7 RNOM INTV C FAULT CC IN INTVCC BAT INTV 10k CC RFB1 22µF 15 FB 1.2V + – 10 IN ENABLE 588k + – + V R FB(REG) FB2 T 10k CHRG CNTRL LOWBAT UVCL V-EA FBG 11 14 ENABLE Li-Ion INTVCC PROG NTC 13 12 NTC HOT DZ RPROG COLD DISABLE – BAT + LOWBAT 2.21V 4120 F01 Figure 1. Block Diagram Rev. G 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Test Circuit Operation Applications Information Package Description Revision History Typical Application Related Parts
