6556B Data Sheet,Content,Features Block Diagram Application Diagram Pin outs Functional Pin Description Operation,Features, Precision Multi-Phase Core Voltage Regulation- Differential Remote Voltage Sensing- 0.5% System Accuracy Over Temperature and Life- Adjustable Reference-Voltage Offset Precision rDS(ON) Current Sensing- Integrated Programmable Temperature Compensation- Accurate Load-Line Programming- Accurate Channel-Current Balancing- Low-Cost, Lossless Current Sensing Microprocessor Voltage Identification Input- Dynamic VID Technology- 6-Bit VID Input- 0.8375V to 1.600V in 12.5mV Steps Enable Function Over current Protection (OCP) Over voltage Protection (OVP) 2, 3, or 4 Phase Operation up to 1.5MHz per Phase,Block Diagram,Application,Multi-Phase,2-Phase,Multi-Phase,3-Phase,4-Phase,Pinouts,Pinouts,Pin function,VCC - Supplies all the power necessary to operate the chip.The controller starts to operate when the voltage on this pinexceeds the rising POR threshold(4.31V) and shuts down when thevoltage on this pin drops below the falling POR threshold(3.82V).Connect this pin directly to a +5V supply or through a series300 resistor to a +12V supply. GND - Bias and reference ground for the IC. EN - This pin is a threshold-sensitive enable input for thecontroller. Connecting the 12V supply to EN through anappropriate resistor divider provides a means to synchronizepower-up of the controller and the MOSFET driver ICs.When EN is driven above 1.24V, the ISL6556B is activedepending on status of ENLL, the internal POR, and pendingfault states. Driving EN below 1.14V will clear all fault statesand prime the ISL6556 to soft-start when re-enabled.,Pin function,FS - A resistor, placed from FS to ground will set the switching frequency. There is an inverse relationship between the value of the resistor and the switching frequency. (80KHz-1500KHz)VID4, VID3, VID2, VID1, VID0, and VID12.5 - These are the inputs to the internal DAC that provides the reference voltage for output regulation.VDIFF, VSEN, and RGND - VSEN and RGND form the precision differential remote-sense amplifier. This amplifier converts the differential voltage of the remote output to a single-ended voltage referenced to local ground. VDIFF is the amplifiers output and the input to the regulation and protection circuitry. Connect VSEN and RGND to the sense pins of the remote load.,Pin function,FB and COMP - Inverting input and output of the erroramplifier respectively. FB is connected to VDIFF through aresistor. A negative current, proportional to output current ispresent on the FB pin. A properly sized resistor betweenVDIFF and FB sets the load line (droop). The droop scalefactor is set by the ratio of the ISEN resistors and the lowerMOSFET rDS(ON). COMP is tied back to FB through anexternal R-C network to compensate the regulator. REF - The REF input pin is the positive input of the Error Amp. It is internally connected to DAC through a 1kresistor. A capacitor is used to between REF pin and ground tosmooth the voltage transition during Dynamic VID operations. TCOMP - Temperature compensation scaling input. Aresistor from this pin to ground sets the temperaturecompensation scales of internal thermal sense circuitry. It used to modify the droop current output to FB to adjust for MOSFET rDS(ON) variations with temperature.,Pin function,PWM1, PWM2, PWM3, PWM4 - Pulse-width modulation outputs. Connect these pins to the PWM input pins of the Intersil driver IC. Tie PWM3 to VCC to configure for 2-phase operation. Tie PWM4 to VCC to configure for 3-phase operation. PGOOD the sign of the end of soft-start per the microprocessor specification. It is an open-drain logic output that is low impedance until the soft-start is completed. It will be pulled low again once the undervoltage point is reached. OFS - The OFS pin provides a means to program a dc current for generating a offset voltage across the droop resistor between FB andVDIFF. The offset current is generated via an external resistor and precision internal voltage references. The polarity of the offset is selected by connecting the resistor to GND or VCC. For no offset, the OFS pin should be left unterminated.,Pin function,ISEN1, ISEN2, ISEN3, ISEN4 - Current sense inputs. The ISEN1, ISEN2, ISEN3, and ISEN4 pins are held to a virtual ground such that a resistor connected between them and the drain terminal of the associated lowerMOSFET will carry a current proportional to the current flowing throughthe related channel. The current is determined by the negative voltage developed across the lower MOSFETs rDS(ON) which is the channel current scaled by the inverse of the rDS(ON). The current is used as a reference for channel balancing, protection, and load-line regulation (via the FB pin). Inactive channels should have their respective current sense inputs left open. OVP - Overvoltage protection pin. This pin pulls to VCC and is latched when an overvoltage condition is detected. Connect this pin to the gate of an SCR or MOSFET tied from VIN or VOUT to ground to prevent damage to the load. This pin may be pulled as high as 15V to ground with an external resistor. However, it is only capable of pulling low when VCC is above 2V.,