Datasheet

LBI

ENABLE

LBO

VIN

Bandgap

LBI

Comparator

Enable to Internal Circuitry

TPS62052, TPS62054

TPS62056, TPS62050, TPS62051

www.ti.com

SLVS432E –SEPTEMBER 2002–REVISED JUNE 2011

Connecting the SYNC pin to the GND pin enables the power-save mode. The converter operates in the PWM

mode at moderate to heavy loads and in the PFM mode during light loads maintaining high efficiency over a wide

load current range.

Power Good Comparator

The power good (PG) comparator has an open drain output capable of sinking typically 1 mA. The PG function is

only active when the device is enabled (EN = high). When the device is disabled (EN = low), the PG pin is pulled

to GND.

The PG output is only valid after a 250 µs delay after the device is enabled and the supply voltage is greater

than 2.7 V. Power good is low during the first 250 µs after shutdown and in shutdown.

The PG pin floats high when the output voltage exceeds typically 98.5% of its nominal value. Leave the PG pin

unconnected, or connect to GND when not used.

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 21. The sum of the resistors R1 and R2 is recommended to be in the

100-kΩ 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.

ENABLE/Low-Battery Detector (Enhanced Version) TPS62051 Only

The TPS62051 offers an enhanced LBI functionality to provide a precise, user programmable undervoltage

shutdown. No additional supply voltage supervisor (SVS) is needed to provide this function.

When the enable (EN) pin is pulled high, only the internal bandgap voltage reference is switched on to provide a

reference source for the LBI comparator. As long as the voltage at LBI is less than the LBI trip point, all other

internal circuits are shut down, reducing the supply current to 5 µA. As soon as input voltage at LBI rises above

the LBI trip point of 1.21 V, the device is completely enabled and starts switching.

Figure 20. Block Diagram of ENABLE/LBI Functionality for TPS62051

The logic level of the LBO pin is not defined for the first 500 µs after EN is pulled high.

When the enhanced LBI is used to supervise the battery voltage and shut down the TPS62051 at low input

voltages, the battery voltage rises again when the current drops to zero. The implemented hysteresis on the LBI

pin may not be sufficient for all types of batteries. Figure 21 shows how an additional external hysteresis can be

implemented.

Product Folder Links: TPS62052 TPS62054 TPS62056 TPS62050 TPS62051