Electronic Components Datasheet Search |
|
LTC4050 Datasheet(PDF) 10 Page - Linear Technology |
|
LTC4050 Datasheet(HTML) 10 Page - Linear Technology |
10 / 16 page 10 LTC4065/LTC4065A 4065fb OPERATIO typical, not worst-case, ambient temperatures for a given application with the assurance that the charger will auto- matically reduce the current in worst-case conditions. The charge cycle begins when the following conditions are met: the voltage at the VCC pin exceeds 3.6V and approxi- mately 80mV above the BAT pin voltage, a program resistor is present from the PROG pin to ground and the EN pin (LTC4065 only) is pulled below the shutdown thresh- old (typically 0.82V). If the BAT pin voltage is below 2.9V, the charger goes into trickle charge mode, charging the battery at one-tenth the programmed charge current to bring the cell voltage up to a safe level for charging. If the BAT pin voltage is above 4.1V, the charger will not charge the battery as the cell is near full capacity. Otherwise, the charger goes into the fast charge constant-current mode. When the BAT pin approaches the final float voltage (4.2V), the LTC4065 enters constant-voltage mode and the charge current begins to decrease. When the current drops to 10% of the full-scale charge current, an internal comparator turns off the N-channel MOSFET on the CHRG pin and the pin assumes a high impedance state. An internal timer sets the total charge time, tTIMER (typi- cally 4.5 hours). When this time elapses, the charge cycle terminates and the CHRG pin assumes a high impedance state. To restart the charge cycle, remove the input voltage and reapply it, momentarily force the EN pin above VMS (typically 0.82V) for LTC4065, or momentarily float the PROG pin and reconnect it (LTC4065A). The charge cycle will automatically restart if the BAT pin voltage falls below VRECHRG (typically 4.1V). When the input voltage is not present, the battery drain current is reduced to less than 4 µA. The LTC4065 can also be shut down by pulling the EN pin above the shutdown threshold voltage. To put LTC4065A in shutdown mode, float the PROG pin. This reduces input quiescent current to less than 20 µAandbatterydraincurrenttolessthan1µA. Programming Charge Current The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge current is 1000 times the current out of the PROG pin. The program resistor and the charge current are calculated using the following equations: R V I I V R PROG CHG CHG PROG == 1000 1 1000 •, The charge current out of the BAT pin can be determined at any time by monitoring the PROG pin voltage and using the following equation: I V R BAT PROG PROG = • 1000 Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in undervoltage lockout until VCC rises above 3.6V and approximately 80mV above the BAT pin voltage. The 3.6V UVLO circuit has a built-in hysteresis of approximately 0.6V and the automatic shut- down threshold has a built-in hysteresis of approximately 50mV. During undervoltage lockout conditions, maxi- mum battery drain current is 4 µA and maximum supply current is 11 µA. Shutdown Mode The LTC4065 can be disabled by pulling the EN pin above the shutdown threshold (approximately 0.82V). The LTC4065A can be disabled by floating the PROG pin. In shutdown mode, the battery drain current is reduced to less than 1 µA and the supply current to about 20µA. Timer and Recharge The LTC4065 has an internal termination timer that starts when an input voltage greater than the undervoltage lockout threshold is applied to VCC, or when leaving shutdown the battery voltage is less than the recharge threshold. At power-up or when exiting shutdown, if the battery voltage is less than the recharge threshold, the charge time is set to 4.5 hours. If the battery voltage is greater than the recharge threshold at power-up or when exiting shut- down, the timer will not start and charging is prevented since the battery is at or near full capacity. |
Similar Part No. - LTC4050 |
|
Similar Description - LTC4050 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |