TPS62080, TPS62080A, TPS62081, TPS62082

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SLVSAE8E – SEPTEMBER 2011 – REVISED APRIL 2015

Feature Description (continued)

8.3.4 Soft-Start

After enabling the device, an internal soft-start circuitry monotonically ramps up the output voltage and reaches

the nominal output voltage during a soft start time (100 µs typical). This avoids excessive inrush current and

creates a smooth output voltage rise slope. It also prevents excessive voltage drops of primary cells and

rechargeable batteries with high internal impedance.

If the output voltage is not reached within the soft start time, such as in the case of heavy load, the converter

enters regular operation. Consequently, the inductor current limit operates as described below. The TPS6208x is

able to start into a pre-biased output capacitor. The converter starts with the applied bias voltage and ramps up

the output voltage to its nominal value.

8.3.5 Undervoltage Lockout

To avoid mis-operation of the device at low input voltages, an undervoltage lockout is implemented that shuts

8.3.6 Thermal Shutdown

temperature falls below the threshold minus hysteresis, the device returns to normal operation automatically.

8.3.7 Inductor Current Limit

The Inductor Current Limit prevents the device from high inductor current and drawing excessive current from the

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

load/shorted output circuit condition.

The incorporated inductor peak current limit measures the current in the high-side and low-side power MOSFET.

Once the high-side switch current limit is tripped, the high-side MOSFET is turned off and the low-side MOSFET

is turned on to reduce the inductor current. When the inductor current drops down to the low-side switch current

limit, the low-side MOSFET is turned off and the high-side switch is turned on again. This operation repeats until

the inductor current does not reach the high-side switch current limit. Due to internal propagation delays, the real

current limit value can exceed the static current limit in Electrical Characteristics.

8.4 Device Functional Modes

8.4.1 Enabling and Disabling the Device

The device is enabled by setting the EN input to a logic HIGH. Accordingly, a logic LOW disables the device. If

the device is enabled, the internal power stage starts switching and regulates the output voltage to the

programmed threshold. The EN input must be terminated with a resistance less than 1M

Ω pulled to VIN or GND.

8.4.2 Power Save Mode

As the load current decreases the TPS6208x enters Power Save Mode operation. During Power Save Mode, the

converter operates with reduced switching frequency in PFM mode and with a minimum quiescent current

maintaining high efficiency. Power Save Mode occurs when the inductor current becomes discontinuous. It is

frequency over the whole load current range is shown in Figure 21 and Figure 22.

8.4.3 Snooze Mode

The TPS6208x offers a Snooze Mode function. If Snooze Mode is enabled by an external logic signal setting the

MODE pin to HIGH, the device's quiescent current consumption is reduced to typically 6.5 µA. As a result, the

high efficiency range is extended towards the range of lowest output currents below 2 mA. See the efficiency

figures in Application Curves.

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