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LM5111

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SNVS300H – JULY 2004 – REVISED SEPTEMBER 2016

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10 Power Supply Recommendations

10.1 Bias Supply Voltage

The recommended bias supply voltage range for LM5111 is from 3.5 V to 14 V. The upper end of this range is

driven by the 15-V absolute maximum voltage rating of the VCC. TI recommends keeping proper margin to allow

for transient voltage spikes. A local bypass capacitor must be placed between the VCC and VEE pins, and this

capacitor must be placed as close to the device as possible. TI recommends a low ESR, ceramic surface mount

capacitor. TI recommends using 2 capacitors across VCC and VEE: a 100-nF ceramic surface-mount capacitor

for high frequency filtering placed very close to VCC and VEE pin, and another surface-mount capacitor, 220 nF

to 10 µF, for IC bias requirements.

11 Layout

11.1 Layout Guidelines

Attention must be given to board layout when using LM5111. Some important considerations include:

•

A Low ESR/ESL capacitor must be connected close to the IC and between the VCC and VEE pins to support

high peak currents being drawn from VCC during turnon of the MOSFET.

•

Proper grounding is crucial. The drivers need a very low impedance path for current return to ground avoiding

inductive loops. The two paths for returning current to ground are a) between LM5111 VEE pin and the ground

of the circuit that controls the driver inputs, b) between LM5111 VEE pin and the source of the power

MOSFET being driven. All these paths should be as short as possible to reduce inductance and be as wide

as possible to reduce resistance. All these ground paths should be kept distinctly separate to avoid coupling

between the high current output paths and the logic signals that drive the LM5111. A good method is to

dedicate one copper plane in a multi-layered PCB to provide a common ground surface.

•

With the rise and fall times in the range of 10 ns to 30 ns, care is required to minimize the lengths of current

carrying conductors to reduce their inductance and EMI from the high di/dt transients generated by the

LM5111.

•

The LM5111 footprint is compatible with other industry standard drivers including the TC4426/27/28 and

UCC27323/4/5.

•

If either channel is not being used, the respective input pin (IN_A or IN_B) should be connected to either VEE

or VCC to avoid spurious output signals.