Features: 1.8 to 5.5V Input Voltage Range Control Turn On 0.15-1.5A Adjustable Current Limit Undervoltage Lockout Thermal Shutdown <2µA Shutdown Current Auto Restart Blanking Reverse Current Latching RoHS Compliant Application: PDA Mobile Phone GPS Device MP3 Player Digital Camera Peripheral Port Hot Swap Supplies

General Instructions

The fpf2163, fpf2164, and fpf2165 are a series of switches that provide comprehensive protection for systems and loads that may encounter high current conditions. These devices contain a 0.12Ω current-limited p-channel MOSFET that can operate from an input voltage range of 1.8-5.5V. when the mosfet is off and the output voltage is higher than the input voltage. Switch control is achieved by a logic input (ON) that can be directly connected to a low voltage control signal. Each section contains a thermal shutdown switch to prevent overheating due to damage to the part under sustained overcurrent conditions. Operates in constant current mode when the switch current reaches the current limit to prevent excessive current that can cause damage. For the fpf2163 and fpf2164, if the constant current condition still exists after 30 minutes, the part will turn off the switch and pull the fault signal pin (flagb) low. The fpf2163 has an auto-restart feature that turns on again after 450ms if the turn-on pin is still active. The FPF2164 has no auto-restart feature, so the switch will remain off until the on-pin is cycled. The FPF2165 does not shut down after a current limit fault, but prefers to remain in constant current mode indefinitely. The minimum current limit is 150mA. These parts are provided as space saving 6-pin 2x2 MLPs.

Operating instructions: fpf2163, fpf2164 and fpf2165 are current-limiting type protection switches that may damage the system and load or be disturbed by strong currents. The core of each device is a 0.12Ω p-channel mosfet and a controller capable of operating over a wide input operating range of 1.8-5.5V. The controller protects against system faults through current limiting, undervoltage lockout, and thermal shutdown. The current limit is adjustable from 150mA to 1.5A through external resistor selection. On/Off Control The ON pin controls the state of the switch. When open high, the switch is on. Keeps active as long as there are no faults, the switch is on. Undervoltage or over 140°C on the VIN will override the open control to close the switch. Also, excessive current will cause switching between fpf2163 and fpf2164. FPF2163 has an auto restart function which will automatically turn on the switch again after 450ms. For the FPF2164, the ON pin must be toggled to turn on and off again. The FPF2165 will not respond to overcurrent conditions, but remains in constant current mode as long as it is on and off or undervoltage lockout has not been activated.

Fault reporting When overcurrent, input undervoltage, or overtemperature is detected, the signal lamp signals a fault to activate LO mode. For fpf2163 and fpf2164, flagb goes low at the end of the blanking time, while flagb FPF2165 goes low immediately. The flag remains low through the FPF2165's auto-restart time. For fpf2164, flagb is locked to lo and must be toggled to on to release it. For the FPF2165, flag B is low during the fault and returns to HI immediately after the fault ends. Flag is an open-drain mosfet that requires a pull-up resistor between Vin and FlagB. During shutdown, the disable flag B is pulled down to reduce the current consumption of the power supply. Current Limit The current limit ensures that the current through the switch does not exceed the maximum value, but is not limited to less than the minimum value. The current limited by the part is adjustable by selecting an external resistor connected to ISET. Find information on selecting resistors in the application information section. The fpf2163 and fpf2164 have a 30ms blank time during which the switch will nominally act as a constant current source. At the end of the blanking time, the switch closes.

The FPF2165 has no current limit blanking period, so it will maintain a constant current state until the ON pin is disabled or thermal shutdown turns off the switch. A heavy-load short-circuit detection feature is introduced in the prevent switch. Short to detect circuit status by observing the output voltage. If the switch load is heavy. When the output voltage is below VSCTH, the short-circuit detection threshold voltage, the current limit is readjusted and the short-circuit current limit is reduced to 62.5% of the current limit. This keeps the power dissipation of the part below a certain limit even under full short-circuit conditions at 5.5V input voltage. VSCTH is set to 1V. The switch is removed from the short circuit current limit mode when the output voltage is about 1.1V and the current limit is set to the current limit value. Undervoltage lockout if the input voltage falls below the undervoltage lockout threshold. The pin active input voltage rises above the undervoltage lockout threshold when on and will cause the switch to turn on in a controlled manner which limits current overcurrent. Reverse Current Blocking The entire fpf2163/65 series has reverse current blocking to protect the input source from output to input. For standard USB power designs, this is an important function to protect the USB host from damage due to reverse current on the VBU. On the other hand, when the load switch is turned, the current blocking function is activated and turned off. If the ON pin is LO and the output voltage is greater than the input voltage voltage, no current can flow from the output to the input. This flagb operates independently of the reverse current blocking function, if this occurs, the fault condition will not be reported that the function is activated. Thermal Shutdown Thermal shutdown protects the mold from excessively high temperatures generated internally or externally. In the overtemperature condition, flag B is activated and the switch is closed. If the mold temperature falls below the threshold temperature, the switch will automatically turn on again.

The following table can also be used to select resource sets. A typical application would be a single USB port. Use the table below to make an appropriate selection since the rset resistance is 394Ω. This will ensure that the port load can tow 525ma, but not more than 875ma. Likewise, for a two-port system, an RSET of 185Ω will always provide at least 1125mA, but no more than 1875mA

The input capacitor limits the input supply voltage drop caused by transients. When the switch is turned on to discharge the load capacitor or short circuit, a capacitor needs to be placed between the VIN and ground. A 0.1UF ceramic capacitor, CIN, placed close to the pin is usually sufficient. Higher cin-can values are used to further reduce voltage drop. The output capacitor should be at Vout and ground. This capacitor prevents parasitic plate inductance from driving the output voltage below ground when the switch is open. For the fpf2163 and fpf2164, the total output capacitance needs to be kept below the maximum value cout(max) to prevent switching off from recording an overcurrent condition. The maximum output capacitance can be determined by the following formula, That's more energy than the package can dissipate, but the component's thermal shutdown will activate to protect the component from damage caused by overheating. When using the FPF2164, care must be taken to manually reset the parts. This junction temperature can only increase up to the turn-off threshold. Once this temperature is reached, before the intersection, opening the switch is not going to drop the temperature. For the FPF2165, the output short circuit will make the part operate in constant current state worst case, This amount of power will activate thermal shutdown as long as the turn-on pin is active and a short exists. Board Layout For best performance, all traces should be as short as possible. To be most effective, input and output capacitors should be placed close to the device to minimize the effects of parasitics during normal and short-circuit operation that may have slight inductance. Using wide traces for VIN (vin), VIN (vout), and ground (gnd) will help minimize parasitic electrical effects while minimizing the thermal impedance of the enclosure to the environment. The middle pad (pin 7) should be connected to the ground plane for improved thermal performance of the load switch. Improper layout can cause junction temperature rise and trigger thermal shutdown protection. This problem occurs when the switch is set at a higher current limit and an overcurrent condition occurs. In this case, the power dissipation switch (Pd = (vin-vout) x ilim(max)) may exceed the maximum absolute power dissipation of 1.2W.