Half-Br Driver
A half-bridge driver translates control signals into appropriate gate drives for the upper and lower power switches. The high-side drive follows a changing switch-node reference. The cited LTC7063 includes adjustable dead time and shoot-through protection. Check the selected driver's functions rather than assuming the same protections from a family label.
The driver shifts or isolates the control signal as needed and charges each power-switch gate relative to its own source/emitter reference. Bootstrap circuits are one way to supply a floating driver, but their recharge conditions must be satisfied. The cited LTC7063 example uses floating grounds and adjustable dead time; those features should not be assumed for a different device without checking its documentation.
In plain terms
Two doors connect a room to different floors. The controller must coordinate when each opens, and leave a safe handover interval so they do not accidentally connect the floors together.
Why designers use it
- Coordinate two power switches in an appropriate half-bridge converter.
- Provide gate drive referenced to the switching node for the high-side device.
- Choose timing, transient immunity and protection functions suited to the power stage.
Best for
- Half-bridge power stages
- Motor-drive switching stages
- Appropriate power converters
Key specifications
- Gate-drive supply: Match driver and power-switch limits (Input logic voltage and output gate voltage are different requirements.)
- Peak source/sink current: Check the specified load and supply (Peak gate current is not continuous load current or a universal switching-time guarantee.)
- Protection and timing: Device-specific (Check UVLO, propagation delay, shutdown state and any required external protection.)
When not to use it
- When required operating voltage, transient immunity, gate drive or isolation exceeds the chosen device's ratings.
- When the proposed bootstrap circuit cannot recharge during the intended switching sequence.
Common mistakes
- Assuming every driver automatically prevents simultaneous conduction of both power switches.
- Comparing bootstrap capacitance directly with gate charge without accounting for allowable voltage droop and other current consumption.
- Ignoring driver return paths, switching-node transients or the transistor's gate-voltage limits.
Where you will find it
- Analog Devices presents an LTC7063-based 2:1 step-down converter with a remote load. The article explains its bootstrap arrangement, floating driver references and adjustable dead time.
- The article compares related LTC706x variants with different input-signal formats. Even closely related driver names do not establish identical control interfaces.
A short history
Half-bridge circuits need drive signals referenced to different power-switch terminals. The cited Analog Devices article explains voltage/current requirements, transient immunity and dead time, then demonstrates the LTC7063's floating-ground architecture. A floating reference is not by itself a galvanic-isolation barrier.
Good to know
- Dead time is an intentional handover pause, not simply an unwanted delay to remove.
- A floating gate-drive reference and a galvanically isolated signal path solve different problems.