The ISL6228 IC is a dual channel synchronous-buck PWM
controller featuring Intersil's Robust Ripple Regulator (R3)
technology that delivers truly superior dynamic response to
input voltage and output load transients. Integrated
MOSFET drivers and bootstrap diodes result in fewer
components and smaller implementation area.
Intersil’s R3 technology combines the best features of fixedfrequency and hysteretic PWMs while eliminating many of
their shortcomings. R3 technology employs an innovative
modulator that synthesizes an AC ripple voltage signal VR,
analogous to the output inductor ripple current. The AC signal
VR enters a window comparator where the lower threshold is
the error amplifier output VCOMP, and the upper threshold is a
programmable voltage reference VW, resulting in generation
of the PWM signal. The voltage reference VW sets the
steady-state PWM frequency. Both edges of the PWM can be
modulated in response to input voltage transients and output
load transients, much faster than conventional fixedfrequency PWM controllers. Unlike a conventional hysteretic
converter, each channel of the ISL6228 has an error amplifier
that provides ±1% voltage regulation at the FB pin.
The ISL6228 has a 1.5ms digital soft-start and can be
started into a pre-biased output voltage. A resistor divider is
used to program the output voltage setpoint. The ISL6228
operates in continuous-conduction-mode (CCM) in heavy
load, and in diode-emulation-mode (DEM) in light load to
improve light-load efficiency. In CCM, the controller always
operates as a synchronous rectifier. In DEM, the low-side
MOSFET is permitted to stay off, blocking negative current
flow into the low-side MOSFET from the output inductor.

Features
• High performance R3 technology
• Fast transient response
• ±1% regulation accuracy: -40°C to +100°C
• Individual power stage input rail for each channel
• Wide input voltage range: +3.3V to +25V
• Output voltage range: +0.6V to +5V
• Diode emulation mode for increased light load efficiency
• Programmable PWM frequency: 200kHz to 600kHz
• Pre-biased output start-up capability
• Integrated MOSFET drivers and bootstrap diode
• Internal digital soft-start
• Power good monitor
• Fault protection
- Undervoltage protection
- Soft crowbar overvoltage protection
- Inductor DCR overcurrent protection
- Over-temperature protection
- Fault identification by PGOOD pull-down resistance
• Pb-free (RoHS compliant)

Applications
• General purpose switching buck regulators
• PCI express graphical processing unit
• Auxiliary power rail
• VRM
• Network adaptor