JAJSU64A April 2024 – August 2024 TPS7H4011-SP
PRODMIX
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Sometimes, the HS1 current limit is not sufficient to protect the device. For example, a short circuit may be so aggressive that even if the high side is only on for the minimum on time, tON, the current would continue to rise. To mitigate this risk, the TPS7H4011 implements a secondary overcurrent protection in the form of high-side overcurrent protection 2 (HS2).
The HS2 current limit is reached when the current through the high side MOSFET meets or exceeds IOC_HS2. To prevent sustained current increase, the next four high-side cycles are skipped while the low side MOSFET remains on in order to discharge the inductor. The simplified waveforms of this operation are shown in Figure 8-18.
Just as the voltage on the ILIM pin sets the high-side 1 current limit, it also sets the high-side 2 current limit. Table 8-5 shows the resulting high-side 2 current limit values that result from utilizing the same suggested resistor divider values as the high-side 1 current limit in Table 8-4.
IOUT
(MAX SUGGESTED DC) (A) |
IOC_HS2
(TYP) (A) |
RILIM_TOP
(kΩ) |
RILIM_BOT
(kΩ) |
---|---|---|---|
3 | 6.6 | ∞ | 0 |
6 | 11.1 | 100 | 49.9 |
9 | 17 | 49.9 | 100 |
12 | 23.9 | 0 | ∞ |