The ISL6228 IC is a dual channel synchronous step-down PWM controller with Intersil's Robust Ripple Regulator (R3) technology to provide truly superior dynamic response to input voltage and output load transients. The integrated MOSFET driver and guide diode result in fewer components and a smaller implementation area.
Intersil's R3 technology combines the best features of fixed frequency and hysteretic pwm while eliminating many of their drawbacks. R3 technology utilizes an innovative modulator that synthesizes an AC ripple voltage signal VR, similar to the output inductive ripple current. The AC signal VR enters the window comparator, where the lower threshold is the error amplifier output VCOMP and the upper threshold is the programmable voltage reference VW, thus generating the PWM signal.
Voltage reference VW Sets the steady-state PWM frequency. Both sides of PWM can be modulated according to input voltage transients and output load transients, much faster than traditional fixed frequency PWM controllers. Unlike conventional hysteresis converters, each channel of the ISL6228 has an error amplifier that provides ±1% voltage regulation at the FB pin.
The ISL6228 features a 1.5ms digital soft boot that can be started to a pre-biased output voltage. Resistance dividers are used to program output voltage Settings. The ISL6228 operates in continuous conduction mode (CCM) under heavy loads and diode simulation mode (DEM) under light loads to improve light load efficiency. In CCM, the controller always operates as a synchronous rectifier. In DEM, the low-side MOSFeTs are allowed to remain off, preventing negative current from flowing into the low-side mosFets from the output inductance.
ISL6228 Pinout
ISL6228 Block Diagram
ISL6228 Typical Application
Features
● High-performance R3 technology
● Fast transient response
● ±1% adjustment accuracy :-40°C to +100°C
● Separate power level input tracks for each channel
● Wide input voltage range :+3.3V to +25V
● Output voltage range :+0.6V to +5V
● Diode simulation mode to improve light load efficiency
● Programmable PWM frequency :200kHz to 600kHz
● Pre-offset output startup capability
● Integrated MOSFET driver and bootstrap diode
● Internal digital soft boot
● A well-powered monitor
● Fail-safe
- Undervoltage protection
- Overvoltage protection for the soft pry bar
- Inductive DCR overcurrent protection
- Overtemperature protection
- Fault identification by PGOOD pull-down resistance
● Lead-free (RoHS compliant)
Applications
● Universal switch step-down regulator
● PCI fast graphics processing unit
● Auxiliary power guide
● VRM
● Network adapter
