TPS709 datasheet(13/43 Pages) TI2

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7.3.3 Undervoltage Lockout (UVLO)

The TPS709 uses an undervoltage lockout (UVLO) circuit to keep the output shut off until the internal circuitry

operates properly.

7.3.4 Reverse-Current Protection

The TPS709 has integrated reverse-current protection. Reverse-current protection prevents the flow of current

from the OUT pin to the IN pin when output voltage is higher than input voltage. The reverse-current protection

circuitry places the power path in high impedance when the output voltage is higher than the input voltage. This

setting reduces leakage current from the output to the input to 10 nA, typical. The reverse current protection is

always active regardless of the enable pin logic state or if the OUT pin voltage is greater than 1.8 V. Reverse

current can flow if the output voltage is less than 1.8 V and if input voltage is less than the output voltage.

If voltage is applied to the input pin, then the maximum voltage that can be applied to the OUT pin is the lower of

three times the nominal output voltage or 6.5 V. For example, if the 1.2-V output voltage version is used, then the

maximum reverse bias voltage that can be applied to the OUT pin is 3.6 V. If the 5.0-V output voltage version is

used, then the maximum reverse bias voltage that can be applied to the OUT pin is 6.5 V.

7.4 Device Functional Modes

The TPS709 has the following functional modes:

1. Enabled: When the enable pin (EN) goes above 0.9 V, the device is enabled. EN is pulled high by a 300-nA

current source; therefore, EN can be left floating to enable the device. Do not connect EN to VIN. The EN

pin is clamped by a 6.5-V Zener diode. Do not exceed the 7-V absolute maximum rating on the enable pin or

excessive current flowing into the Zener clamp will destroy the device.

2. Disabled: When EN goes below 0.4 V, the device is disabled. During this time, OUT is high impedance and

the current into IN (I(SHUTDOWN)) is typically 150 nA.

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TPS709

SBVS186H – MARCH 2012 – REVISED JULY 2021

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