MOSFET driver features adaptive-dead-time and shoot-through protection for 1/2-bridge

January 09, 2014 // By Julien Happich
Micrels’ MIC4605 is an 85V Half-bridge MOSFET driver featuring adaptive-dead-time and shoot-through protection. The adaptive-dead-time circuitry actively monitors the Half-bridge to minimise the time between high and low side MOSFET transitions, which maximises power efficiency.

The 5.5V to 16V operating supply range further increases system efficiency. Anti-shoot-through circuitry prevents erroneous inputs and noise from turning both MOSFETs on at the same time. The Adaptive-Dead-Time (ADT) circuitry actively monitors the MOSFETs in the Half Bridge switch circuit allowing only one MOSFET to be active at a time, thus assuring no cross conduction condition that can destroy the Half Bride circuit. The ADT circuitry also keeps the transitions between High side and Low Side MOSFET as short possible to minimise power losses due to long dead-time the degrade the power efficiency. The ADT circuitry eliminates the need to design in dead-time margin and time delay between HI and LI inputs to protect against cross conduction reducing the headroom requirements of the microcontroller. In addition, the 85V operating voltage offers  margin for protection against voltage spikes which are present in motor drive and power supply applications.

The MIC4605 features 30 nsec propagation delay times and 35 nsec driver rise/fall times for a 1 nF capacitive load. For MIC4605 -1, TTL inputs provide independent control of the low-side and high-side gate drivers. The MIC4605 -2 has a single PWM input for both low-side and high-side gate drivers. The outputs do not overlap in either mode. An internal, high-voltage Schottky diode charges the high-side, gate-drive bootstrap (external) capacitor. The IC is available in an 8-pin SOIC package and a 0-pin 2.5 × 2.5mm TDFN package. Both packages have an operating junction temperature range of –40°C to +125°C.