TPS62085

TPS62086

TPS62087

SLVSB70 – OCTOBER 2013

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An internal pull-down resistor of 400 k

Ω is connected to the EN pin when the EN pin is LOW. The pull-down

resistor is disconnected when the EN pin is High.

SOFT START

The TPS62085, TPS62086, and TPS62087 have an internal soft start circuitry which monotonically ramps up the

output voltage and reaches the nominal output voltage during a soft start time of typical 0.8 ms. This avoids

excessive inrush current and creates a smooth output voltage slope. It also prevents excessive voltage drops of

primary cells and rechargeable batteries with high internal impedance. The device is able to start into a pre-

biased output capacitor. The device starts with the applied bias voltage and ramps the output voltage to its

nominal value.

SWITCH CURRENT LIMIT AND HICCUP SHORT CIRCUIT PROTECTION

The switch current limit prevents the devices from high inductor current and from drawing excessive current from

the battery or input voltage rail. Excessive current might occur with a shorted/saturated inductor or a heavy

turned off and the low-side MOSFET is turned on to ramp down the inductor current. Once this switch current

limits is triggered 32 times, the devices stop switching and enables the output discharge. The devices then

automatically start a new startup after a typical delay time of 66 µs has passed. This is named HICCUP short

circuit protection. The devices repeat this mode until the high load condition disappears.

POWER GOOD

The TPS62085, TPS62086, and TPS62087 have a power good output. The power good goes high impedance

once the output is above 95% of the nominal voltage, and is driven low once the output voltage falls below

typically 90% of the nominal voltage. The PG pin is an open drain output and is specified to sink up to 1 mA. The

power good output requires a pull-up resistor connecting to any voltage rail less than 6 V. The power good goes

low when the devices are disabled or in thermal shutdown. When the devices are in UVLO, the PG pin is high

impedance.

The PG signal can be used for sequencing of multiple rails by connecting it to the EN pin of other converters.

Leave the PG pin unconnected when not used.

UNDER VOLTAGE LOCKOUT

To avoid mis-operation of the device at low input voltages, an under voltage lockout is implemented, which shuts

THERMAL SHUTDOWN

the device temperature falls below the threshold by 20°C, the device returns to normal operation automatically.

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Product Folder Links: TPS62085 TPS62086 TPS62087