Datasheet

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Soft Start

Overvoltage Protection

Undervoltage Lockout

Overtemperature Shutdown

TPS65130, TPS65131

SLVS493B – MARCH 2004 – REVISED SEPTEMBER 2004

DETAILED DESCRIPTION (continued)

Both converters have implemented soft-start functions. When each converter is enabled, the implemented switch

current limit ramps up slowly to its nominal programmed value in about 1 ms. Soft start is implemented to limit

the input current during start-up to avoid high peak currents at the battery which could interfere with other

systems connected to the same battery. Without soft start, uncontrolled input peak currents flow to charge up the

output capacitors and to supply the load during start-up. Their values could increase the implemented switch

current limit, which has serious impact to the converter itself and other parts of the system, by causing significant

voltage drops across the series resistance of the battery and its connections.

Both built-in converters have implemented overvoltage protection. If the feedback voltage under normal operation

exceeds the nominal value by typically 5%, the corresponding converter shuts down immediately to protect any

connected circuitry from possible damage.

An undervoltage lockout prevents the device from starting up and operating if the supply voltage at VIN is lower

than the programmed threshold shown in the electrical characteristic table. The device automatically shuts down

both converters when the supply voltage at VIN falls below this threshold. Nevertheless, parts of the control

circuits remain active, which is different than device shutdown using EN inputs. The undervoltage lockout

function is implemented to prevent device malfunction.

The device automatically shuts down both converters if the implemented internal temperature detector detects a

chip temperature above the programmed theshold shown in the electrical characteristics table. It automatically

starts operating again when the chip temperature falls below this threshold. A built-in hysteresis avoids undefined

operation caused by ringing from shutdown and prevents operating at a temperature close to the

overtemperature shutdown threshold.