ZHCSMK6B September 2021 – November 2022 TPSM82864A , TPSM82866A
PRODUCTION DATA
The switch current limit prevents the device from high inductor current and from drawing excessive current from the battery or input voltage rail. Excessive current can occur with a heavy load or shorted output circuit condition. If the inductor current reaches the threshold ILIM, cycle by cycle, the high-side MOSFET is turned off and the low-side MOSFET is turned on until the inductor current ramps down to the low-side MOSFET current limit.
When the high-side MOSFET current limit is triggered 256 times, the device stops switching. The device then automatically re-starts with soft start after a typical delay time of 16 ms has passed. The device repeats this mode until the high load condition disappears. This HICCUP short-circuit protection reduces the current consumed from the input supply because the device only draws input current approximately 10% of the time during an overload condition. Figure 9-29 shows the hiccup short-circuit protection.
The low-side MOSFET also contains a negative current limit to prevent excessive current from flowing back through the inductor to the input. If the low-side sinking current limit is exceeded, the low-side MOSFET is turned off. In this scenario, both MOSFETs are off until the start of the next cycle. The negative current limit is only active in forced PWM mode.