[FAQ] LM5109: Differences between LM5109A and LM5109B

Part Number: LM5109

There have been questions regarding the differences between the LM5109A and LM5109B 100V high-side low-side drivers.

The pinout, available packages and parameter specifications are the same for the LM5109A and LM5109B. So the LM5109B is a drop in replacement for the LM5109A.

The LM5109B has design changes that ensure that the HO level shifter properly initializes the HO output to the default low state when VDD drops below the UVLO threshold, in the event that the HB to HS bias is still above the HB UVLO threshold. The LM5109A has some conditions where VDD could droop or sag below UVLO and the HO output may not be properly initialized to the low state.

TI recommends using the LM5109B instead of the LM5109A based on this improvement to the device.

The LM5109 gate driver was set to NRND, not recommended for new designs, some time ago. So the LM5109B is the recommended device to use over the LM5109 and LM5109A.

Richard Herring

1 Reply