JAJSMS4F August 2021 – March 2024 TPS7H2211-SEP , TPS7H2211-SP
PRODUCTION DATA
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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, IF, 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
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 IF = 0.65 mA, ΔVOUT = 12 V, COUT = 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
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 IF current. It is recommended to ensure the resistor can handle the worst case power dissipation when the switch is enabled and VOUT ≈ VIN.