Datasheet LT3651-4.1, LT3651-4.2 (Analog Devices) - 7
| Fabricante | Analog Devices |
| Descripción | Monolithic 4A High Voltage 1 Cell Li-Ion Battery Charger |
| Páginas / Página | 22 / 7 — PIN FUNCTIONS. NTC (Pin 1):. GND (Pins 6, 23, 31, 37):. SW (Pins 7, … |
| Formato / tamaño de archivo | PDF / 285 Kb |
| Idioma del documento | Inglés |
PIN FUNCTIONS. NTC (Pin 1):. GND (Pins 6, 23, 31, 37):. SW (Pins 7, 11-18, 22, 38):. ACPR (Pin 2):. TIMER (Pin 24):. BAT (Pin 3):
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LT3651-4.1/LT3651-4.2
PIN FUNCTIONS NTC (Pin 1):
Battery Temperature Monitor Pin. This
GND (Pins 6, 23, 31, 37):
Ground. These pins are the pin is used to monitor battery temperature. Typically a ground pins for the part. Pins 31 and 37 must be connected 10kΩ NTC (negative temperature coefficient) thermistor together. Pins 6 and 23 are connected via the leadframe to (B = 3380) is embedded with the battery and connected the exposed backside Pin 37. Solder the exposed backside from the NTC pin to ground. The pin sources 50µA into to the PCB for good thermal and electrical connection. the resistor and monitors the voltage across the therm-
SW (Pins 7, 11-18, 22, 38):
Switch Output Pin. These istor, regulating charging based on the voltage. If this pins are the output of the charger switches. An inductor function is not desired, leave the NTC pin unconnected. is connected between this pin and the SENSE pin. When
ACPR (Pin 2):
Open-Collector AC Present Status Pin. the switcher is active, the inductor is charged by the high This pin sinks current to indicate that VIN is valid and the side switch from VIN and discharged by the bottom side charger is on. Typically a resistor pull-up is used on this switch to GND. Solder the exposed backside, Pin 38, to pin. This pin can be pulled up to voltages as high as VIN the PCB for good thermal connection. when disabled, and can sink currents up to 10mA when
TIMER (Pin 24):
End-Of-Cycle Timer Programming Pin. enabled. A capacitor on this pin to ground determines the full
BAT (Pin 3):
Battery Voltage Monitor Pin. This pin moni- charge end-of-cycle time. Full charge end-of-cycle time is tors battery voltage. A Kelvin connection is made to the programmed with this capacitor. A 3 hour charge cycle is battery from this pin and a decoupling capacitor (CBAT) obtained with a 0.68µF capacitor. This timer also controls is placed from this pin to ground. the bad battery fault that is generated if the battery does not The charge function operates to achieve the final float reach the precondition threshold voltage within one-eighth voltage at this pin. The auto-restart feature initiates a new of a full cycle (22.5 minutes for a 3 hour charge cycle). charging cycle when the voltage at the BAT pin falls 2.5% The timer based termination is disabled by connecting the below this float voltage. Once the charge cycle is termi- TIMER pin to ground. With the timer function disabled, nated, the input bias current of the BAT pin is reduced to charging terminates when the charge current drops below a <0.1µA to minimize battery discharge while the charger C/10 rate, or approximately 10% of maximum charge rate. remains connected.
FAULT (Pin 25):
Open-Collector Fault Status Output. This
SENSE (Pin 4):
Charge Current Sense Pin. The charge pin indicates charge cycle fault conditions during a battery current is monitored with a sense resistor (RSENSE) con- charging cycle. Typically a resistor pull-up is used on this nected between this pin and the BAT pin. The inductor pin. This status pin can be pulled up to voltages as high current flows through RSENSE to the battery. The voltage as VIN when disabled, and can sink currents up to 10mA across this resistor sets the average charge current. The when enabled. A temperature fault causes this pin to be maximum average charge current (IMAX) corresponds to pulled low. If the internal timer is used for termination, 95mV across the sense resistor. a bad battery fault also causes this pin to be pulled low.
BOOST (Pin 5):
Bootstrapped Supply Rail for Switch If no fault conditions exist, the FAULT pin remains high Drive. This pin facilitates saturation of the high side switch impedance. transistor. Connect a 1µF or greater capacitor from the BOOST pin to the SW pin. The operating range of this pin is 2V to 4.5V, referenced to the SW pin when the switch is high. The voltage on the decoupling capacitor is refreshed through a rectifying diode, with the anode connected to either the battery output voltage or an external source, and the cathode connected to the BOOST pin. 365142ff For more information www.linear.com/LT3651-4.1 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Pin Functions Block Diagram Operation Applications Information Typical Applications Revision History Typical Application Related Parts
PIN FUNCTIONS NTC (Pin 1):
Battery Temperature Monitor Pin. This
GND (Pins 6, 23, 31, 37):
Ground. These pins are the pin is used to monitor battery temperature. Typically a ground pins for the part. Pins 31 and 37 must be connected 10kΩ NTC (negative temperature coefficient) thermistor together. Pins 6 and 23 are connected via the leadframe to (B = 3380) is embedded with the battery and connected the exposed backside Pin 37. Solder the exposed backside from the NTC pin to ground. The pin sources 50µA into to the PCB for good thermal and electrical connection. the resistor and monitors the voltage across the therm-
SW (Pins 7, 11-18, 22, 38):
Switch Output Pin. These istor, regulating charging based on the voltage. If this pins are the output of the charger switches. An inductor function is not desired, leave the NTC pin unconnected. is connected between this pin and the SENSE pin. When
ACPR (Pin 2):
Open-Collector AC Present Status Pin. the switcher is active, the inductor is charged by the high This pin sinks current to indicate that VIN is valid and the side switch from VIN and discharged by the bottom side charger is on. Typically a resistor pull-up is used on this switch to GND. Solder the exposed backside, Pin 38, to pin. This pin can be pulled up to voltages as high as VIN the PCB for good thermal connection. when disabled, and can sink currents up to 10mA when
TIMER (Pin 24):
End-Of-Cycle Timer Programming Pin. enabled. A capacitor on this pin to ground determines the full
BAT (Pin 3):
Battery Voltage Monitor Pin. This pin moni- charge end-of-cycle time. Full charge end-of-cycle time is tors battery voltage. A Kelvin connection is made to the programmed with this capacitor. A 3 hour charge cycle is battery from this pin and a decoupling capacitor (CBAT) obtained with a 0.68µF capacitor. This timer also controls is placed from this pin to ground. the bad battery fault that is generated if the battery does not The charge function operates to achieve the final float reach the precondition threshold voltage within one-eighth voltage at this pin. The auto-restart feature initiates a new of a full cycle (22.5 minutes for a 3 hour charge cycle). charging cycle when the voltage at the BAT pin falls 2.5% The timer based termination is disabled by connecting the below this float voltage. Once the charge cycle is termi- TIMER pin to ground. With the timer function disabled, nated, the input bias current of the BAT pin is reduced to charging terminates when the charge current drops below a <0.1µA to minimize battery discharge while the charger C/10 rate, or approximately 10% of maximum charge rate. remains connected.
FAULT (Pin 25):
Open-Collector Fault Status Output. This
SENSE (Pin 4):
Charge Current Sense Pin. The charge pin indicates charge cycle fault conditions during a battery current is monitored with a sense resistor (RSENSE) con- charging cycle. Typically a resistor pull-up is used on this nected between this pin and the BAT pin. The inductor pin. This status pin can be pulled up to voltages as high current flows through RSENSE to the battery. The voltage as VIN when disabled, and can sink currents up to 10mA across this resistor sets the average charge current. The when enabled. A temperature fault causes this pin to be maximum average charge current (IMAX) corresponds to pulled low. If the internal timer is used for termination, 95mV across the sense resistor. a bad battery fault also causes this pin to be pulled low.
BOOST (Pin 5):
Bootstrapped Supply Rail for Switch If no fault conditions exist, the FAULT pin remains high Drive. This pin facilitates saturation of the high side switch impedance. transistor. Connect a 1µF or greater capacitor from the BOOST pin to the SW pin. The operating range of this pin is 2V to 4.5V, referenced to the SW pin when the switch is high. The voltage on the decoupling capacitor is refreshed through a rectifying diode, with the anode connected to either the battery output voltage or an external source, and the cathode connected to the BOOST pin. 365142ff For more information www.linear.com/LT3651-4.1 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Pin Functions Block Diagram Operation Applications Information Typical Applications Revision History Typical Application Related Parts