LM5102 Waveforms

Operational Notes

The LM5102 offers a unique flexibility with independently

programmable delay of the rising edge for both high and low

side driver outputs independently. The delays are set with

resistors at the RT1 and RT2 pins, and can be adjusted from

100 ns to 600 ns. This feature reduces component count,

board space and cost compared to discrete solutions for

adjusting driver dead time. The wide delay programming

range provides the flexibility to optimize drive signal timing

for a wide range of MOSFETs and applications.

The RT pins are biased at 3V and current limited to 1 mA

maximum programming current. The time delay generator

will accommodate resistor values from 5k to 100k with

turn-on delay times that are proportional to the RT resis-

tance. In addition, each RT pin is monitored by a comparator

that will bypass the turn-on delay if the RT pin is pulled below

the timer elimination threshold (1.8V typical). Grounding the

RT pins programs the LM5102 to drive both outputs with

minimum turn-on delay.

STARTUP AND UVLO

Both top and bottom drivers include under-voltage lockout

(UVLO) protection circuitry which monitors the supply volt-

age (V

independently. The UVLO circuit inhibits each driver until

sufficient supply voltage is available to turn-on the external

MOSFETs, and the built-in hysteresis prevents chattering

during supply voltage transitions. When the supply voltage is

applied to V

20088903

(a)

20088904

(b)

FIGURE 3. Application Timing Waveforms

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