FB

PG

VIN

8

LBO

GND

SYNC

EN

LBI

PGND

TPS62051

SW

1

6

7

3

2

9

5

4

10

R3

R4

R1

R2

R5

R6

R7

1 Cell Li-lon

L1 = 10

µH

6.8 pF

LBI

ENABLE

LBO

VIN

Bandgap

LBI

Comparator

Enable to Internal Circuitry

TPS62050, TPS62051, TPS62052, TPS62054, TPS62056

www.ti.com

SLVS432F – SEPTEMBER 2002 – REVISED JUNE 2015

Feature Description (continued)

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

The TPS62051 device 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 4. 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 5 shows how an additional external hysteresis can be

implemented.

Figure 5. Enhanced LBI With Increased Hysteresis

9.3.4 Undervoltage Lockout

The undervoltage lockout (UVLO) circuit prevents the device from misoperation at low input voltages. The circuit

prevents the converter from turning on the switch or rectifier MOSFET under undefined conditions.

Copyright © 2002–2015, Texas Instruments Incorporated

Submit Documentation Feedback

9

Product Folder Links: TPS62050 TPS62051 TPS62052 TPS62054 TPS62056