LM7480 datasheet(23/43 Pages) TI

23 / 43 page

SO 7637-2 Pulse 2 A can also be absorbed by input and output capacitors and its amplitude could be reduced

to 40-V peak by placing sufficient amount of capacitance at input and output. However for this 12-V design,

maximum system voltage is 50 V and a 60-V VDS rated MOSFET is selected.

The VGS rating of the MOSFET Q2 should be higher than that maximum HGATE-OUT voltage 15 V.

Inrush current through the MOSFET during input hot-plug into the 12-V battery is determined by output

capacitance. External capacitor on HGATE, CDVDT is used to limit the inrush current during input hot-plug or

startup. The value of inrush current determined by Equation 2 need to be selected to ensure that the MOSFET

Q2 is operating well within its safe operating area (SOA). To limit inrush current to 250 mA, value of CDVDT is

10.43 nF, closest standard value of 10.0 nF is chosen.

Duration of inrush current is calculated by

(7)

Calculated inrush current duration is 2.36 ms with 250-mA inrush current.

MOSFET BUK7Y4R8-60E having 60-V VDS and ±20-V VGS rating is selected for Q2. Power dissipation during

inrush is well within the MOSFET's safe operating area (SOA).

10.2.6 TVS Selection

A 600-W SMBJ TVS such as SMBJ33CA is recommended for input transient clamping and protection. For

detailed explanation on TVS selection for 12-V battery systems, refer to TVS Selection for 12-V Battery Systems.

10.2.7 Application Curves

Figure 10-2. Startup 12 V with EN Pulled to VIN

Figure 10-3. Startup 12 V showing Charge Pump

VCAP

www.ti.com

LM7480

SNOSDD8 – DECEMBER 2022

Submit Document Feedback

Product Folder Links: LM7480

LM7480 Datasheet(PDF) 23 Page - Texas Instruments