Specifications
18 mA
2 mA
22.5 mA
27.5 mA
Normal Operation
Region
80% Tolerance
25 mA
10% Tolerance
10
mA
On state, Open load/
Short to Battery
TPS1H100-Q1
SLVSCM2A –OCTOBER 2014–REVISED JANUARY 2014
www.ti.com
8.3.4.1 Short to GND/Overload Detection
In the on state, the short to GND fault is reported as the low status output or V
CS,h
on CS, when current limit is
triggered. The smaller one of the internal or external set value is applied for the actual current limit. It is in auto-
recovery when the fault condition is cleared. If not cleared, thermal shutdown triggers to protect the power FET.
8.3.4.2 Open Load Detection
In the on state, for version A, if the current flowing through the output is less than I
ol,on
, the device recognizes an
open load fault. For version B, diagnostics are diagnosed by reading the voltage on the CS pin, it is judged by
the user. As a benefit from high accuracy current sense down to very-small current range, this device can
achieve very-low open load detection threshold, which respectively expands the normal operation region. TI
suggests 10 mA as the upper limit for the open-load detection threshold and 25 mA as the lower limit for the
normal operation current. In Figure 35, 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.
Figure 35. 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. When open load, the output voltage is
close to the supply voltage, V
S
– V
OUT
< V
ol,off
. For version A, the ST pin will go low to indicate the fault to MCU.
For version B, the CS pin will be pulled up to V
CS,h
. There is always a leakage current I
ol,off
present on the output,
due to internal logic control path or external humidity, corrosion, and so forth. Thus, TI recommends an external
pullup resistor to offset the leakage current. This pullup current should be less than output load current to avoid
misdetection in the normal operation mode. To reduce the standby current, TI recommends to always use a
switch for the pullup resistor. TI recommends R
pu
≤ 15 kΩ.
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