EN

VIN

ON

OFF

0.3

µA, min

R >1.3 V/0.3

µA

TPS6205x

5 V

EN

VIN

VIN

0

Typically 0.3

Enable to Internal Circuitry

TPS62050, TPS62051, TPS62052, TPS62054, TPS62056

SLVS432F – SEPTEMBER 2002 – REVISED JUNE 2015

www.ti.com

9.3 Feature Description

9.3.1 Enable and Overtemperature Protection

A logic low on EN forces the TPS6205x devices into shutdown. In shutdown, the power switch, drivers, voltage

reference, oscillator, and all other functions are turned off. The supply current is reduced to less than 2 µA in the

shutdown mode. When the device is in thermal shutdown, the bandgap is forced to stay on even if the device is

set into shutdown by pulling EN to GND. As soon as the temperature drops below the threshold, the device

automatically starts again.

If an output voltage is present when the device is disabled, which could be an external voltage source or super

cap, the reverse leakage current is specified under Electrical Characteristics. Pulling the enable pin high starts up

the TPS6205x devices with the soft-start as described in Soft-Start. If the EN pin is connected to any voltage

Figure 2. Internal Circuit of the ENABLE Pin

The EN pin can be used in a pushbutton configuration as shown in Figure 3. The external resistor to GND must

be capable of sinking 0.3 µA with a minimum voltage drop of 1.3 V to keep the system enabled when both

switches are open. When the ON-button is pressed, the device is enabled and the current through the external

resistor keeps the voltage level high to ensure that the device stays on when the ON-button is released. When

the OFF-button is pressed, the device is switched off and the current through the external resistor is zero. The

device therefore stays off even when the OFF-button is released.

Figure 3. Pushbutton Configuration for the EN-Pin

9.3.2 Low-Battery Detector (Standard Version)

The low-battery output (LBO) is an open-drain type which goes low when the voltage at the low battery input

(LBI) falls below the trip point of 1.21 V ±1.5%. The voltage at which the low-battery warning is issued is adjusted

with a resistive divider as shown in Figure 5. TI recommends the sum of the resistors R1 and R2 to be in the

100-k

Ω to 1-MΩ range for high-efficiency at low output current. An external pullup resistor at LBO can either be

connected to OUT, or any other voltage rail in the voltage range of 0 V to 6 V. During start-up, the LBO output

signal is invalid for the first 500 µs. LBO is high impedance when the device is disabled. If the low-battery

comparator function is not used, connect LBI to ground. The low-battery detector is disabled when the device is

disabled. Leave the LBO pin unconnected, or connect to GND when not used.

8

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