LM5045MHXSLASHNOPB datasheet(34/47 Pages) TI2

34 / 47 page

LM5045

SNVS699H – FEBRUARY 2011 – REVISED JANUARY 2015

www.ti.com

9 Power Supply Recommendations

The LM5045 can be used to control power levels up to 1 kW. Therefore the current levels can be considerable.

Care should be taken that components with the correct current rating are chosen. This would include magnetic

components, power MOSFETS and diodes, connectors and wire sizes. Input and output capacitors should have

the correct ripple current rating. The use of a multilayer PCB is recommended with a copper area chosen to

ensure the LM5045 is operating below its maximum junction temperature.

Full power loading should never be attempted with providing with providing adequate cooling.

10 Layout

10.1 Layout Guidelines

The LM5045 current sense and PWM comparators are very fast and respond to short duration noise pulses. The

components at the CS, COMP, SLOPE, RAMP, SS, SSSR, RES, UVLO, OVP, RD1, RD2, and RT pins should

be physically close as possible to the IC, thereby minimizing noise pickup on the PC board trace inductance.

Eliminating or minimizing via’s in these critical connections are essential. Layout consideration is critical for the

current sense filter. If a current sense transformer is used, both leads of the transformer secondary should be

routed to the sense filter components and to the IC pins. The ground side of the transformer should be

connected via a dedicated PC board trace to the AGND pin, rather than through the ground plane. If the current

sense circuit employs a sense resistor in the drive transistor source, low inductance resistors should be used. In

this case, all the noise sensitive, low-current ground trace should be connected in common near the IC, and then

a single connection made to the power ground (sense resistor ground point).

The gate drive outputs of the LM5045 should have short, direct paths to the power MOSFETs to minimize

inductance in the PC board. The boot-strap capacitors required for the high side gate drivers should be located

very close to the IC and connected directly to the BST and HS pins. The VCC and REF capacitors should also

be placed close to their respective pins with short trace inductance. Low ESR and ESL ceramic capacitors are

recommended for the boot-strap, VCC and the REF capacitors. The two ground pins (AGND, PGND) must be

connected together directly underneath the IC with a short, direct connection, to avoid jitter due to relative ground

bounce.

Submit Documentation Feedback

Product Folder Links: LM5045

LM5045MHX/NOPB Datasheet(PDF) 34 Page - Texas Instruments