LM5574, LM5574-Q1

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SNVS478F – JANUARY 2007 – REVISED APRIL 2013

PIN DESCRIPTIONS (continued)

Pin(s)

Name

Description

Application Information

15

PRE

Pre-charge assist for the bootstrap

This open drain output can be connected to SW pin to aid

capacitor

charging the bootstrap capacitor during very light load conditions

or in applications where the output may be pre-charged before

the LM5574 is enabled. An internal pre-charge MOSFET is

turned on for 250ns each cycle just prior to the on-time interval

of the buck switch.

16

BST

Boost input for bootstrap capacitor

An external capacitor is required between the BST and the SW

pins. A 0.022µF ceramic capacitor is recommended. The

capacitor is charged from Vcc via an internal diode during the

off-time of the buck switch.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

Absolute Maximum Ratings

(1) (2)

76V

BST to GND

90V

PRE to GND

76V

SW to GND (Steady State)

-1.5V

76V

14V

BST to SW

14V

OUT to GND

Limited to Vin

SYNC, SS, FB, RAMP to GND

7V

Human Body Model

2kV

Storage Temperature Range

-65°C to +150°C

(1)

Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical Characteristics.

(2)

If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and

specifications.

(3)

The human body model is a 100pF capacitor discharged through a 1.5k

Ω resistor into each pin.

Operating Ratings

(1)

6V to 75V

Operation Junction Temperature

−40°C to + 125°C

(1)

Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical Characteristics.

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