Datasheet

NCL30051
http://onsemi.com
15
A boost circuit comprised of D
boost
and C
boost
generates
the supply voltage for the high side driver. Once HDRVlo
turns on, the HVS pin is effectively grounded through the
external power switch. This allows C
boost
to charge to V
CC
.
Once HDRVlo turns off, HVS floats high and D
boost
is
reversed biased. An undervoltage detector monitors the
HBoost voltage. Once the HBoost voltage is greater than
V
Boost(UV)
, typically, 6.1 V, the high side driver is enabled.
The low side driver generally starts before the high side
driver because the boost voltage is generated by the low
side driver switch transitions.
The half−bridge low side driver source and sink
impedances are typically 75 and 15 W, respectively. The
half−bridge high side driver source and sink impedances
are typically 75 and 15 W, respectively. Depending on the
external MOSFETs gate charge requirements, an external
driver may be needed to drive the low and high side power
switches.
Analog and Power Ground
The NCL30051 has an analog ground, GND, and a power
ground, PGND, terminal. GND is used for analog
connections such as VREF and OSC. PGND is used for
high current connections such as the gate drivers. It is
recommended to have independent analog and power
ground planes and connect them at a single point,
preferably at the ground terminal of the system. This will
prevent high current flowing on PGND from injecting
noise in GND. The PGND connection should be as short
and wide as possible to reduce inductance−induced spikes.