LM5176PWPR datasheet(19/45 Pages) TI2

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The COMP output voltage (VCOMP) range limits the possible VIN and IOUT ranges for a given design. In buck

mode, the maximum VIN for which the converter can regulate the output at no load is when VCOMP reaches 0.3 V.

Equation 7 gives VCOMP as a function of VIN at no load in CCM buck mode:

OUT

COMP(BUCK)

SENSE

BUCK

SLOPE

2 S V

6 A

1.6 V

1 D

2 L1 F

P ˜

(7)

Where DBUCK in Equation 7 is the buck duty cycle given by:

OUT

BUCK

(8)

A larger L1, lower slope ripple (higher CSLOPE), smaller sense resistor (RSENSE), and higher frequency can

increase the maximum VIN range for buck operation.

For boost mode, the minimum VIN for which the converter can regulate the output at full load is when VCOMP

reaches 3 V. Equation 9 gives VCOMP as a function of VIN in boost mode:

OUT

COMP(BOOST)

SENSE

OUT

BOOST

SLOPE

2 S V

5 A

1.6 V

2 L1 F

P ˜

(9)

Where DBOOST in Equation 9 is the boost duty cycle given by:

BOOST

OUT

(10)

A larger L1, lower slope ripple (higher CSLOPE), smaller sense resistor (RSENSE), and higher frequency can

extend the minimum VIN range for boost operation.

7.3.14 Integrated Gate Drivers

The LM5176 provides four N-channel MOSFET gate drivers: two floating high-side gate drivers at the HDRV1

and HDRV2 pins, and two ground referenced low-side drivers at the LDRV1 and LDRV2 pins. Each driver is

capable of sourcing 1.8-A and sinking 2.2-A peak current. In buck operation, LDRV1 and HDRV1 are switched

by the PWM controller while HDRV2 remains continuously on. In boost operation, LDRV2 and HDRV2 are

switched while HDRV1 remains continuously on.

The low-side gate drivers are powered from VCC and the high-side gate drivers HDRV1 and HDRV2 are

powered from bootstrap capacitors CBOOT1 (between BOOT1 and SW1) and CBOOT2 (between BOOT2 and

SW2), respectively. The CBOOT1 and CBOOT2 capacitors are charged through external Schottky diodes connected

to the VCC pin as shown in Figure 8-1.

In most applications, ceramic capacitors of 16-V or higher voltage rating and values between 0.1 µF and 0.22 µF

are sufficient for CBOOT1 and CBOOT2.

7.3.15 Thermal Shutdown

The LM5176 is protected by a thermal shutdown circuit that shuts down the device when the internal junction

temperature exceeds 165°C (typical). The soft-start capacitor is discharged when thermal shutdown is triggered

and the gate drivers are disabled. The converter automatically restarts when the junction temperature drops by

the thermal shutdown hysteresis of 15°C below the thermal shutdown threshold.

7.4 Device Functional Modes

Refer to Section 7.3.3 for the description of EN/UVLO pin function. Section 7.4.1 lists the shutdown, standby,

and operating modes for LM5176 as a function of EN/UVLO and VCC voltages.

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LM5176

SNVSAI1D – JUNE 2017 – REVISED AUGUST 2021

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