9.2.5 Controlled Power Down (Quick Output Discharge) using TPS2595x5

When the TPS2595x5 device is disabled, the output voltage is left floating and the power-down profile is entirely dictated by the load. In some applications, this can lead to undesired activity because the load is not powered down to a defined state. Controlled output discharge can ensure the load is completely turned off and is not in an undefined operational state. The QOD pin in the TPS2595x5 device can be connected to the OUT pin to facilitate the Quick Output Discharge function, as shown in Figure 62. When the TPS2595x5 device is disabled, the QOD pin is pulled low and provides a quick discharge path for the output capacitor. The output voltage discharge rate is dictated by the output capacitor C_OUT, the total discharge path resistance (internal plus external), and the load.

Figure 62. Circuit Implementation with Quick Output Discharge Function using TPS2595x5

Figure 63. Output Voltage Discharge using TPS259535 without QOD [V_IN = 5 V, EN = H → L, C_OUT = 100 µF, R_LOAD = 1000 Ω, R_QODEXT = OPEN]

Figure 64. Output Voltage Discharge using TPS259535 with QOD [V_IN = 5 V, EN = H → L, C_OUT = 100 µF, R_LOAD = 1000 Ω, R_QODEXT = Short]