Datasheet

TPS61200

TPS61201

TPS61202

SLVS577D –MARCH 2007–REVISED MARCH 2013

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Softstart and Short-Circuit Protection

During start-up of the converter, the duty cycle and the peak current are limited in order to avoid high peak

currents drawn from the battery. After being enabled, the device starts operating. At first, it keeps the main output

VOUT disconnected, and charges the capacitor at VAUX. Once the capacitor at VAUX is charged to about 2.5 V,

the device switches to normal operation. This means VOUT is turned on and the capacitor at VOUT is charged,

while the load connected to the device is supplied. To ramp up the output voltage in a controlled way, the

average current limit is set to 400 mA and rises proportional to the increase of the output voltage. 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 does not increase. There is no timer implemented. Thus the output voltage overshoot at startup, as well as

the inrush current, is kept at a minimum. The device ramps up the output voltage in a controlled manner even if a

large capacitor is connected at the output. When the output voltage does not increase above 1.2 V, the device

assumes a short-circuit at the output, and keeps the current limit low to protect itself and the application. When

there is a short at the output during operation, the current limit is decreased accordingly.

The device can also start into a Prebias on the outputs.

Current Limit

The device current limit limits the average current in the inductor. In a boost connector, this is the input current. If

an excessive load requires an input current greater than the average current limit, the device limits the input

current by reducing the output power delivered. In this case, the output voltage decreases.

Undervoltage Lockout

An undervoltage lockout function prevents the main output at VOUT from being supplied if the voltage at the

UVLO pin drops below 0.25 V. When using a resistive divider at the voltage to be monitored, for example the

supply voltage, any threshold for the monitored voltage can be programmed. If in undervoltage lockout mode, the

device still maintains its supply voltage at VAUX, and it is not turned off until EN is programmed low. This

undervoltage lockout function is implemented in order to prevent the malfunctioning of the converter.

Thermal Shutdown

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 unstable operation at IC temperatures at the thermal shutdown threshold.

Product Folder Links: TPS61200 TPS61201 TPS61202