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LTC4090-3 Datasheet(PDF) 10 Page - Linear Technology |
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LTC4090-3 Datasheet(HTML) 10 Page - Linear Technology |
10 / 30 page LTC4090-3 10 40903fb For more information www.linear.com/LTC4090-3 CLPROG (Pin 14): 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: ICL(A)= 1000V RCLPROG In USB applications, the resistor RCLPROG should be set to no less than 2.1k. The voltage on the CLPROG pin is alwaysproportionaltothecurrentflowingthroughtheINto OUT power path. This current can be calculated as follows: IIN(A)= VCLPROG RCLPROG •1000 HPWR(Pin15):HighPowerSelect.Thislogicinputisused 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 current is internally connected to this pin to ensure it is low at power up when the pin is not being driven externally. SUSP (Pin 16): Suspend Mode Input. Pulling this pin above 1.2V will disable the power path from IN to OUT. The supply current from IN will be reduced to comply with the USB specification for suspend mode. Both the ability to charge the battery from HVIN and the ideal diode function (from BAT to OUT) will remain active. Suspend mode will reset the charge timer if OUT is less than BAT while in suspend mode. If OUT is kept greater than BAT, such as when the high voltage input is present, the charge timer will not be reset when the part is put in suspend. A 2µA pull-down current is internally connected to this pin to ensure it is low at power up when the pin is not being driven externally. TIMER (Pin 17): Timer Capacitor. Placing a capacitor, CTIMER, to GND sets the timer period. The timer period is: tTIMER(hours)= CTIMER •RPROG •3hours 0.1µF •100k Charge time is increased if charge current is reduced due to load current, thermal regulation and current limit selection (HPWR low). Shorting the TIMER pin to GND disables the battery charging functions. HVOUT (Pin 18): Voltage Output of the High Voltage Regulator. When sufficient voltage is present at HVOUT, the low voltage power path from IN to OUT will be dis- connected and the HVPR pin will be pulled low to indicate that a high voltage wall adapter has been detected. The LTC4090 high voltage regulator will maintain just enough differential voltage between HVOUT and BAT to keep the battery charger MOSFET out of dropout (typically 300mV from OUT to BAT). HVOUT should be bypassed with at least 22µF to GND. BOOST (Pin 19): This pin is used to provide drive voltage, higher than the input voltage, to the internal bipolar NPN power switch. SW (Pin 20): The SW pin is the output of the internal high voltage power switch. Connect this pin to the inductor, catch diode and boost capacitor. HVIN(Pin21):HighVoltageRegulatorInput.TheHVINpin supplies current to the internal high voltage regulation and to the internal high voltage power switch. The presence of a high voltage input takes priority over the USB VBUS input (i.e., when a high voltage input supply is detected, the USB IN to OUT path is disconnected). This pin must be locally bypassed. HVEN (Pin 22): High Voltage Regulator Enable Input. The HVEN pin is used to disable the high voltage input path. Tie to ground to disable the high voltage input or tie to at least 2.3V to enable the high voltage path. If this feature is not used, tie HVEN to the HVIN pin. This pin can also be used to soft-start the high voltage regulator; see the Applications Information section for more information. Exposed Pad (Pin 23): Ground. The exposed package pad is ground and must be soldered to the PC board for proper functionality and for maximum heat transfer (use several vias directly under the LTC4090-3). PIN FUNCTIONS |
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Similar Description - LTC4090-3_15 |
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