Electronic Components Datasheet Search |
|
LTC4075X Datasheet(PDF) 10 Page - Linear Technology |
|
LTC4075X Datasheet(HTML) 10 Page - Linear Technology |
10 / 16 page LTC4075/LTC4075X 10 4075Xfa *Any external sources that hold the ITERM pin above 100mV will prevent the LTC4075 from terminating a charge cycle. The termination condition is detected by using an internal filtered comparator to monitor the ITERM pin. When the ITERM pin voltage drops below 100mV* for longer than tTERMINATE (typically 1.5ms), charging is terminated. The charge current is latched off and the LTC4075 enters standby mode. When charging, transient loads on the BAT pin can cause the ITERM pin to fall below 100mV for short periods of time before the DC charge current has dropped below the programmed termination current. The 1.5ms filter time (tTERMINATE) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. Once the average charge current drops below the programmed termination threshold, the LTC4075 terminates the charge cycle and ceases to provide any current out of the BAT pin. In this state, any load on the BAT pin must be supplied by the battery. Low Battery Charge Conditioning (Trickle Charge) This feature ensures that near-dead batteries are gradually charged before reapplying full charge current . If the BAT pin voltage is below 2.9V, the LTC4075 supplies 1/10th of the full charge current to the battery until the BAT pin rises back above 2.9V. For example, if the charger is programmed to charge at 800mA from the wall adapter input and 500mA from the USB input, the charge current during trickle charge mode would be 80mA and 50mA, respectively. The LTC4075X does not include the trickle charge feature; it outputs full charge current to the battery when the BAT pin voltage is below 2.9V. The LTC4075X is useful in applications where the trickle charge current may be insufficient to supply the load during low battery voltage conditions. Automatic Recharge In standby mode, the charger sits idle and monitors the battery voltage using a comparator with a 6ms filter time (tRECHRG). A charge cycle automatically restarts when the battery voltage falls below 4.1V (which corresponds to approximately 80%-90% battery capacity). This ensures that the battery is kept at, or near, a fully charged condi- tion and eliminates the need for periodic charge cycle initiations. If the battery is removed from the charger, a sawtooth waveform of approximately 100mV appears at the battery output. This is caused by the repeated cycling between termination and recharge events. This cycling results in pulsing at the ⎯C⎯H⎯R⎯G output; an LED connected to this pin will exhibit a blinking pattern, indicating to the user that a battery is not present. The frequency of the sawtooth is dependent on the amount of output capacitance. Manual Shutdown The ENABLE pin has a 2M Ω pulldown resistor to GND. The definition of this pin depends on which source is supplying power. When the wall adapter input is supplying power, logic low enables the charger and logic high disables it (the pulldown defaults the charger to the charging state). The opposite is true when the USB input is supplying power; logic low disables the charger and logic high enables it (the default is the shutdown state). The DCIN input draws 20µA when the charger is in shut- down. The USBIN input draws 18µA during shutdown if no power is applied to DCIN, but draws only 10µA when VDCIN > VUSBIN. Charge Current Soft-Start and Soft-Stop The LTC4075 includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. When a charge cycle is initiated, the charge current ramps from zero to full-scale current over a period of 250µs. Likewise, internal circuitry slowly ramps the charge current from full-scale to zero in a period of approximately 30µs when the charger shuts down or self terminates. This minimizes the transient current load on the power supply during start-up and shut-off. Status Indicators The charge status output ( ⎯C⎯H⎯R⎯G)hastwostates:pull-down and high impedance. The pull-down state indicates that the LTC4075 is in a charge cycle. Once the charge cycle has terminated or the LTC4075 is disabled, the pin state becomes high impedance. The pull-down state is capable of sinking up to 10mA. OPERATIO |
Similar Part No. - LTC4075X_15 |
|
Similar Description - LTC4075X_15 |
|
|
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 |