TPS63000
TPS63001
TPS63002
www.ti.com
SLVS520–MARCH 2006
DETAILED DESCRIPTION (continued)
Device Enable
The device is put into operation when EN is set high. It is put into a shutdown mode when EN is set to GND. In
shutdown mode, the regulator stops switching, all internal control circuitry is switched off and the load is
disconnected from the input. This also means that the output voltage can drop below the input voltage during
shutdown. During start-up of the converter, the duty cycle and the peak current are limited in order to avoid high
peak currents flowing from the input.
Softstart and Short Circuit Protection
When the device enables, the device starts operating. The average current limit is ramping up from an initial
400mA following the output voltage increasing. At an output voltage of about 1.2 V the current limit is at its
nominal value. If the output voltage does not increase, the current limit will not increase. There is no timer
implemented. Thus the output voltage overshoot at startup is kept at a minimum as well as the inrush current at
the input. The device ramps up the output voltage in a controlled manner even if a very large capacitor is
connected at the output. When the output voltage does not increase above 1.2 V the device is assuming a short
circuit at the output and keeps the current limit low to protect itself and the application. At a short at the output
during operation the current limit also will be decreased accordingly. At 0 V at the output for example the output
current will not exceed abaout 400 mA.
Undervoltage Lockout
An undervoltage lockout function prevents device start-up if the supply voltage on VINA is lower than
approximately its threshold (see electrical characteristics table). When in operation the device automatically
enters the shutdown mode if the voltage on VINA drops below the undervoltage lockout threshold. The device
automatically restarts if the input voltage recovers to the minimum operating input voltage.
Overtemperature Protection
The device has a built in temperature sensor which monitors the internal IC 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. There is a built in
hysteresis to avoid instable operation at IC temperatures at the overtemperature threshold.
7
Submit Documentation Feedback
TI [ TEXAS INSTRUMENTS ]
