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LTC4055 Datasheet(PDF) 8 Page - Linear Technology |
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LTC4055 Datasheet(HTML) 8 Page - Linear Technology |
8 / 24 page LTC4085 8 4085fd IN (Pin 1): Input Supply. Connect to USB supply, VBUS. Input current to this pin is limited to either 20% or 100% of the current programmed by the CLPROG pin as deter- mined by the state of the HPWR pin. Charge current (to BAT pin) supplied through the input is set to the current programmed by the PROG pin but will be limited by the input current limit if charge current is set greater than the input current limit. OUT (Pin 2): Voltage Output. This pin is used to provide controlled power to a USB device from either USB VBUS (IN) or the battery (BAT) when the USB is not present. This pin can also be used as an input for battery charging when the USB is not present and a wall adapter is applied to this pin. OUT should be bypassed with at least 4.7μF to GND. CLPROG (Pin 3): Current Limit Program and Input Cur- rent Monitor. Connecting a resistor, RCLPROG, to ground programs the input to output current limit. The current limit is programmed as follows: I CL (A) = 1000V R CLPROG In USB applications the resistor RCLPROG should be set to no less than 2.1k. The voltage on the CLPROG pin is always proportional to the current flowing through the IN to OUT power path. This current can be calculated as follows: I IN(A) = V CLPROG R CLPROG • 1000 HPWR (Pin 4): High Power Select. This logic input is used to control the input current limit. A voltage greater than 1.2V on the pin will set the input current limit to 100% of the current programmed by the CLPROG pin. A voltage less than 0.4V on the pin will set the input current limit to 20% of the current programmed by the CLPROG pin. A 2μA pull-down is internally applied to this pin to ensure it is low at power up when the pin is not being driven externally. SUSP (Pin 5): Suspend Mode Input. Pulling this pin above 1.2V will disable the power path from IN to OUT. The sup- ply current from IN will be reduced to comply with the USB specification for suspend mode. Both the ability to charge the battery from OUT and the ideal diode function (from BAT to OUT) will remain active. Suspend mode will reset the charge timer if VOUT is less than VBAT while in suspend mode. If VOUT is kept greater than VBAT, such as when a wall adapter is present, the charge timer will not be reset when the part is put in suspend. A 2μA pull-down is internally applied to this pin to ensure it is low at power up when the pin is not being driven externally. TIMER (Pin 6): Timer Capacitor. Placing a capacitor, CTIMER, to GND sets the timer period. The timer period is: t TIMER(Hours) = C TIMER •RPROG • 3Hours 0.1μF • 100k Charge time is increased if charge current is reduced due to undervoltage current limit, load current, thermal regulation and current limit selection (HPWR). Shorting the TIMER pin to GND disables the battery charg- ing functions. PIN FUNCTIONS |
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Similar Description - LTC4055 |
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