ISL68236IRAZ datasheet(21/107 Pages) RENESAS

21 / 107 page

ISL68225, ISL68236

4. Operating the Device

R16DS0047EU0100 Rev.1.00

Page 21 of 106

Oct.1.20

Operating the Device

After the ISL68225 and ISL68236 initialize and a configuration is loaded, they are ready for operation.

The ISL68225 and ISL68236 have several performance enhancing features that enable them to meet the most

stringent voltage regulation and efficiency demands. The synthetic current modulator provides excellent transient

response to support the latest generation of ASICs and CPUs. Automatic phase dropping, diode emulation, and

PFM operation improve efficiency across the load range. The ISL68225 and ISL68236 support Smart Power

Stage (SPS) current sense and DCR/resistor current sense to enable optimal design. The devices also support a

full complement of high-resolution telemetry, including per-phase temperature sense when paired with select

Renesas SPS devices. The following sections provide more detail about using these features.

4.1

Input Voltage Sensing

Input voltage is monitored using the VINSEN pin. Connect the VINSEN pin as shown in Figure 7.

Input voltage is monitored continuously, and regulation is stopped anytime the sensed input voltage falls outside

the boundaries established by configuration settings associated with the parameters VIN ON, VIN OFF, VIN

Overvoltage Fault Limit, and VIN Undervoltage Fault Limit.

4.2

Lossless Input Current and Power Sensing

Input current telemetry is provided per rail using an input current synthesizer. By using the ability of the ISL68225

and ISL68236 to precisely determine their operational conditions, the input current can be synthesized to a high

degree of accuracy without the need for a lossy sense resistor. With a precise knowledge of input current and

voltage, the input power can be computed.

4.3

VMON Voltage Sensing

The VMON input pin provides a secondary input voltage sense with several selectable voltage ranges. The

VMON input pin can be used to inhibit rail operation when the sensed voltage falls outside the boundary

established by the configuration settings that are associated with the parameters VMON_ON and VMON_OFF. If

a rail is prevented from operating due to a VMON excursion, the rail restarts if the sensed voltage returns to the

specified range. Use of this feature is optional for each rail. A typical use case for this voltage sensing feature is

monitoring the bias supply voltage associated with the power stages and preventing operation if this voltage is

below the configured range. Connection of the VMON pin for sensing the 5V SPS bias voltage is shown in

Figure 8.

Figure 7. Input Voltage Sense Configuration

Figure 8. VMON Configuration

ISL68236IRAZ Datasheet(PDF) 21 Page - Renesas Technology Corp