10

LM5111

SNVS300H – JULY 2004 – REVISED SEPTEMBER 2016

www.ti.com

Product Folder Links: LM5111

Submit Documentation Feedback

Copyright © 2004–2016, Texas Instruments Incorporated

8.3 Feature Description

8.3.1 Undervoltage Lockout

An undervoltage lockout (UVLO) circuit is included in the LM5111, which senses the voltage difference between

VCC and the chip ground pin, VEE. When the VCC to VEE voltage difference falls below 2.8 V both driver channels

are disabled. The UVLO hysteresis prevents chattering during brown-out conditions and the driver resumes

normal operation when the VCC to VEE differential voltage exceeds approximately 3 V.

The LM5111-1, -2, and -3 devices hold both outputs in the low state in the UVLO condition. The LM5111-4 is

distinguished from the LM5111-3 by the active high output state of OUT_A during UVLO. When VCC is less than

the UVLO threshold voltage, OUT_A of the LM5111-4 will be locked in the high state while OUT_B will be

disabled in the low state. This configuration allows the LM5111-4 to drive a PFET through OUT_A and an NFET

through OUT_B with both FETs safely turned off during UVLO.

8.3.2 Output Stage

The two driver channels of the LM5111 are designed as identical cells. Transistor matching inherent to integrated

circuit manufacturing ensures that the AC and DC peformance of the channels are nearly identical. Closely

matched propagation delays allow the dual driver to be operated as a single with inputs and output pins

connected. The drive current capability in parallel operation is precisely 2× the drive of an individual channel.

Small differences in switching speed between the driver channels will produce a transient current (shoot-through)

in the output stage when two output pins are connected to drive a single load. Differences in input thresholds

between the driver channels will also produce a transient current (shoot-through) in the output stage. Fast

transition input signals are especially important while operating in a parallel configuration. The efficiency loss for

parallel operation has been characterized at various loads, supply voltages and operating frequencies. The

power dissipation in the LM5111 increases be less than 1% relative to the dual driver configuration when

operated as a single driver with inputs/ outputs connected.

8.4 Device Functional Modes

Table 2. Input/output Logic Table

LM5111-1M

LM5111-2M

LM5111-3M/LM5111-4M

IN A

IN B

OUT A

OUT B

IN A

IN B

OUT A

OUT B

IN A

IN B

OUT A

OUT B

L

L

L

L

L

L

H

H

L

L

H

L

L

H

L

H

L

H

H

L

L

H

H

H

H

L

H

L

H

L

L

H

H

L

L

L

H

H

H

H

H

H

L

L

H

H

L

H

In UVLO

L

L

In UVLO

L

L

In UVLO

L/H

L/L