Datasheet

Undervoltage Lockout
Overvoltage Protection
Overtemperature Protection
TPS61220
TPS61221
TPS61222
SLVS776 – JANUARY 2009 ............................................................................................................................................................................................... www.ti.com
An implemented undervoltage lockout function stops the operation of the converter if the input voltage drops
below the typical undervoltage lockout threshold. This function is implemented in order to prevent malfunctioning
of the converter.
If, for any reason, the output voltage is not fed back properly to the input of the voltage amplifier, control of the
output voltage will not work anymore. Therefore an overvoltage protection is implemented to avoid the output
voltage exceeding critical values for the device and possibly for the system it is supplying. For this protection the
TPS6122x output voltage is also monitored internally. In case it reaches the internally programmed threshold of
6.5 V typically the voltage amplifier regulates the output voltage to this value.
If the TPS6122x is used to drive LEDs, this feature protects the circuit if the LED fails.
The device has a built-in temperature sensor which monitors the internal IC junction temperature. If the
temperature exceeds the programmed threshold (see electrical characteristics table), the device stops operating.
As soon as the IC temperature has decreased below the programmed threshold, it starts operating again. To
prevent unstable operation close to the region of overtemperature threshold, a built-in hysteresis is implemented.
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