TPS1HC100-Q1
ZHCSLK6A –JULY 2021 –REVISED DECEMBER 2021
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Current Sense
Voltage
VSNSFH
ADC Full Scale Range, VADC,max
Headroom, VHR
Over Current
Max Measurable Current
Max Nominal Current
1
Normal
RSNS
Open Load Current, VADC,min
Sense Current
图8-2. Voltage Indication on the Current-Sense Pin
The maximum current the system wants to read, ILOAD,max, must be below the current limit threshold because
after the current limit threshold is tripped the VSNS value goes to VSNSFH. Additionally, currents being measured
must be below 6 A to ensure that the current sense output is not saturated.
VBAT
VBB
Iout/K
Iout/KILIM
VSNSFH
Iout
Voltage
Scaling
–
+
DIAG_EN
VOUT
CURRENT
CLAMP
Vcl,th
SNS
ILIM
RSNS
RILIM
图8-3. Current-Sense and Current-Limit Block Diagram
Because this scheme adapts based on the voltage coming in from the MCU, there is no need to have a Zener
diode on the SNS pin to protect from high voltages.
8.3.2 Programmable Current Limit
A high-accuracy current limit allows higher reliability, which protects the power supply during short circuit or
power up. Also, a current limit can save system costs by reducing PCB traces, connector size, and the capacity
of the preceding power stage.
Current limiting offers protection from over-stressing to the load and integrated power FET. The current limit
regulates the output current to the set value, and pulls up the SNS pin to VSNSFH and asserts the FLT pin as
diagnostic reports. The three current-limit thresholds are:
• External programmable current limit –an external resistor, RILIM, is used to set the channel current limit.
When the current through the device exceeds ICL (current limit threshold), a closed loop steps in immediately.
VGS voltage regulates accordingly, leading to the VDS voltage regulation. When the closed loop is set up, the
current is clamped at the set value. The external programmable current limit provides the capability to set the
current-limit value by application.
Additionally, this value can be dynamically changed by changing the resistance on the ILIM pin. This
information can be seen in the Applications section.
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