When VIN is powered but the TPS7H2211 is disabled (EN is low), the internal FETs are disabled, creating a high impedance path from VIN to VOUT. However, there are parasitic leakage paths that could cause VOUT to slowly charge. The forward leakage current, I_F, indicates how much current flows from VIN to VOUT during this situation. This is typically 0.65 mA at VIN = 12 V but could be a maximum of 1.3 mA at 14 V.

Some applications may tolerate these leakage mechanisms while some applications may need to pay particular attention to this behavior. It is particularly relevant when VOUT is a high impedance node (and therefore the leakage current goes entirely to charging VOUT instead of being dissipated). By using the basic capacitor equation shown in Equation 8, the time for the voltage to rise to a given value can be theoretically calculated.

where

• Δt = time to charge to final value
• ΔV_OUT = change in output voltage; for a 0 V starting voltage, use V_IN

For example, with a 12-V input voltage and a 220-µF output capacitance, VOUT will typically charge to 12 V in 4.1 seconds (using I_F = 0.65 mA, ΔV_OUT = 12 V, C_OUT = 220 µF).

If the output voltage must remain below a certain value, a pull-down resistor can be utilized with a value as calculated by Equation 9.

where

• VOUT_{LKG_MAX} = maximum output voltage due to leakage current, I_F
• R_{PULL_DOWN} = external pull-down resistor from VOUT to GND

For example, placing a 1-kΩ resistor between VOUT and ground will ensure VOUT does not rise above 0.65-V typically or 1.3-V worse case due to the I_F current. It is recommended to ensure the resistor can handle the worst case power dissipation when the switch is enabled and VOUT ≈ VIN.