SNVS349E February 2005 – August 2016 LM5105
PRODUCTION DATA.
7 Detailed Description
7.1 Overview
The LM5105 is a single PWM input Gate Driver with Enable that offers a programmable dead time. The dead time is set with a resistor at the RDT pin and can be adjusted from 100 ns to 600 ns. The wide dead-time programming range provides the flexibility to optimize drive signal timing for a wide range of MOSFETS and applications.
The RDT pin is biased at 3 V and current-limited to 1-mA maximum programming current. The time delay generator accommodates resistor values from 5 k to 100 k with a dead time that is proportional to the RDT resistance. Grounding the RDT pin programs the LM5105 to drive both outputs with minimum dead time.
7.2 Functional Block Diagram
7.3 Feature Description
7.3.1 Start-Up and UVLO
Both top and bottom drivers include undervoltage lockout (UVLO) protection circuitry, which monitors the supply voltage (VDD) and bootstrap capacitor voltage (HB – HS) independently. The UVLO circuit inhibits each driver until sufficient supply voltage is available to turn on the external MOSFETs, and the UVLO hysteresis prevents chattering during supply voltage transitions. When the supply voltage is applied to the VDD pin of LM5105, the top and bottom gates are held low until VDD exceeds the UVLO threshold, typically about 6.9 V. Any UVLO condition on the bootstrap capacitor disables only the high-side output (HO).
7.4 Device Functional Modes
Table 1 lists the functional modes for LM5105.
Table 1. Function Table
| EN | IN PIN | LO PIN | HO PIN |
|---|---|---|---|
| L | Any | L | L |
| H | H | L | H |
| H | L | H | L |