CHL8550_15 Datasheet, PDF (10/15 Pages) International Rectifier – High‐Efficiency Variable Gate MOSFET Driver

High‐Efficiency Variable Gate MOSFET Driver _CHL8550
GENERAL DESCRIPTION
The CHL8550 is a high‐efficiency, fast MOSFET driver with
large source and sink current capability. It can reliably
drive the external high‐ and low‐side N‐channel MOSFETs
with large input capacitance at switching frequencies up to
1MHz. The patented IR Active Tri‐Level (ATL) feature allows
complete control over enable and disable of both MOSFETs
using the PWM input signal from the controller. The timing
and voltage levels of ATL are shown in Figure 6.
During normal operation the PWM transitions between
low and high voltage levels to drive the low‐ and high‐side
MOSFETs. The PWM signal falling edge transition to a low
voltage threshold initiates the high‐side driver turn off
after a short propagation delay, t_PDL(HS). The dead time
control circuit monitors the HI_GATE and switch voltages
to ensure the high‐side MOSFET is turned off before the
LO_GATE voltage is allowed to rise to turn on the low‐side
MOSFET.
The PWM rising edge transition through the high‐side turn
on threshold, initiates the turn off of the low‐side MOSFET
after a small propagation delay, t_PDL(LS). The adaptive
dead time circuit provides the appropriate dead time by
determining if the falling LO_GATE voltage threshold has
been crossed before allowing the HI_GATE voltage to rise
and turn on the high‐side MOSFET, t_PDH(HS).
10 December 6, 2011 | FINAL | V1.05