TPS1HC30-Q1
ZHCSP75A –JULY 2022 –REVISED DECEMBER 2022
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Current (A)
ICL_ENPS
ICL_LINPK
ICL
INOM
tRETRY
Thermal Shutdown
Time (s)
图8-14. Overload Behavior
In all of these cases, the internal thermal shutdown is safe to hit repetitively. There is no device risk or lifetime
reliability concerns from repeatedly hitting this thermal shutdown level.
8.3.4.2 Open-Load and Short-to-Battery Detection
When the main channel is enabled, faults are diagnosed by reading the voltage on the SNS or FLT pin and
judged by the user. A benefit of high-accuracy current sense is that this device can achieve a very low open-load
detection threshold, which correspondingly expands the normal operation region. TI suggests 15 mA as the
upper limit for the open-load detection threshold and 30 mA as the lower limit for the normal operation current. In
图 8-15, the recommended open-load detection region is shown as the dark-shaded region and the light-shaded
region is for normal operation. As a guideline, do not overlap these two regions.
Normal Operation
Region
27.5 mA
10% Tolerance
25 mA
22.5 mA
18 mA
80% Tolerance
On State, Open Load/
Short to Battery
10 mA
2 mA
图8-15. On-State Open-Load Detection and Normal-Operation Diagram
In the off state, if a load is connected, the output voltage is pulled to 0 V. In the case of an open load, the output
voltage is close to the supply voltage, VBB – VOUT < Vol,off. The FLT pin goes low to indicate the fault to the
MCU, and the SNS pin is pulled up to VSNSFH. There is always a leakage current Iol,off present on the output, due
to the internal logic control path or external humidity, corrosion, and so forth. Thus, TI implemented an internal
pullup resistor to offset the leakage current. This pullup current must be less than the output load current to avoid
false detection in the normal operation mode. To reduce the standby current, TI implemented a switch in series
with the pullup resistor controlled by the DIAG_EN pin. The pullup resistor value is Rpu = 150 kΩ.
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