Datasheet LT3652 (Analog Devices) - 7

LT3652
PIN FUNCTIONS VIN (Pin 1):
Charger Input Supply. VIN operating range to be pul ed low. If the internal timer is used for termina- is 4.95V to 32V. VIN must be 3.3V greater than the pro- tion, a bad battery fault also causes this pin to be pul ed grammed output battery float voltage (VBAT(FLT)) for reli- low. If no fault conditions exist, the FAULT pin remains able start-up. (VIN – VBAT(FLT)) ≥ 0.75V is the minimum high-impedance. operating voltage, provided (VBOOST – VSW) ≥ 2V. IVIN ~
TIMER (Pin 6):
End-Of-Cycle Timer Programming Pin. 85µA after charge termination. If a timer-based charge termination is desired, connect
VIN_REG (Pin 2):
Input Voltage Regulation Reference. a capacitor from this pin to ground. Full charge end-of- Maximum charge current is reduced when this pin is below cycle time (in hours) is programmed with this capacitor 2.7V. Connecting a resistor divider from VIN to this pin following the equation: enables programming of minimum operational VIN voltage. t This is typical y used to program the peak power voltage EOC = CTIMER • 4.4 • 106 for a solar panel. The LT3652 servos the maximum charge A bad battery fault is generated if the battery does not current required to maintain the programmed operational achieve the precondition threshold voltage within one- VIN voltage, through maintaining the voltage on VIN_REG eighth of tEOC, or: at or above 2.7V. If the voltage regulation feature is not t used, connect the pin to V PRE = CTIMER • 5.5 • 105 IN. A 0.68µF capacitor is typical y used, which generates a
SHDN (Pin 3):
Precision Threshold Shutdown Pin. The timer EOC at three hours, and a precondition limit time of enable threshold is 1.2V (rising), with 120mV of input 22.5 minutes. If a timer-based termination is not desired, hysteresis. When in shutdown mode, all charging functions the timer function is disabled by connecting the TIMER are disabled. The precision threshold al ows use of the pin to ground. With the timer function disabled, charging SHDN pin to incorporate UVLO functions. If the SHDN pin terminates when the charge current drops below a C/10 is pul ed below 0.4V, the IC enters a low current shutdown threshold, or I mode where V CHG(MAX)/10 IN current is reduced to 15µA. Typical SHDN pin input bias current is 10nA. If the shutdown function
VFB (Pin 7):
Battery Float Voltage Feedback Reference. The is not desired, connect the pin to V charge function operates to achieve a final float voltage of IN. 3.3V on this pin. Output battery float voltage (V
CHRG (Pin 4):
Open-Collector Charger Status Output; BAT(FLT)) is programmed using a resistor divider. V typical y pul ed up through a resistor to a reference volt- BAT(FLT) can be programmed up to 14.4V. age. This status pin can be pul ed up to voltages as high as V The auto-restart feature initiates a new charging cycle IN when disabled, and can sink currents up to 10mA when enabled. During a battery charging cycle, if required when the voltage at the VFB pin falls 2.5% below the float charge current is greater than 1/10 of the programmed voltage reference. maximum current (C/10), CHRG is pul ed low. A tem- The VFB pin input bias current is 110nA. Using a resistor perature fault also causes this pin to be pul ed low. After divider with an equivalent input resistance at the VFB pin C/10 charge termination or, if the internal timer is used of 250k compensates for input bias current error. for termination and charge current is less than C/10, the CHRG pin remains high-impedance. Required resistor values to program desired VBAT(FLT) follow the equations:
FAULT (Pin 5):
Open-Collector Charger Status Output; typical y pul ed up through a resistor to a reference volt- R1 = (VBAT(FLT) • 2.5 • 105)/3.3 (Ω) age. This status pin can be pul ed up to voltages as high R2 = (R1 • 2.5 • 105)/(R1 - (2.5 • 105)) (Ω) as VIN when disabled, and can sink currents up to 10mA R1 is connected from BAT to V when enabled. This pin indicates fault conditions during a FB, and R2 is connected from V battery charging cycle. A temperature fault causes this pin FB to ground. 3652fe For more information www.linear.com/LT3652 7 Document Outline Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Package Description Typical Application Related Parts