ISL62883IRTZ Intersil, ISL62883IRTZ Datasheet - Page 17

• Manufacturer Part Number: ISL62883IRTZ
• Description: IC REG PWM 3PHASE BUCK 40TQFN
• Manufacturer: Intersil

Specifications of ISL62883IRTZ

• Applications: Controller, Intel IMVP-6.5™
• Voltage - Input: 5 V ~ 21 V
• Number Of Outputs: 1
• Voltage - Output: 0.0125 V ~ 1.5 V
• Operating Temperature: -40°C ~ 100°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Since the slave ripple capacitor voltages mimic the
inductor currents, R
excellent current balancing during steady state and
dynamic operations. Figure 12 shows current balancing
performance of the ISL62883 evaluation board with load
transient of 12A/51A at different rep rates. The inductor
currents follow the load current dynamic change with the
output capacitors supplying the difference. The inductor
currents can track the load current well at low rep rate,
but cannot keep up when the rep rate gets into the
hundred-kHz range, where it’s out of the control loop
bandwidth. The controller achieves excellent current
balancing in all cases.
CCM Switching Frequency
The R
sets the sets the VW windows size, therefore sets the
switching frequency. When the ISL62883 is in continuous
conduction mode (CCM), the switching frequency is not
absolutely constant due to the nature of the R
modulator. As explained in the Multiphase R
section, the effective switching frequency will increase
during load insertion and will decrease during load
release to achieve fast response. On the other hand, the
switching frequency is relatively constant at steady state.
Variation is expected when the power stage condition,
such as input voltage, output voltage, load, etc. changes.
The variation is usually less than 15% and doesn’t have
any significant effect on output voltage ripple magnitude.
Equation 17 gives an estimate of the frequency-setting
resistor R
300kHz switching frequency. Lower resistance gives
higher switching frequency.
Phase Count Configurations
The ISL62883 can be configured for 3-, 2- or 1-phase
operation.
For 2-phase configuration, tie the PWM3 pin to 5V.
Phase-1 and Phase-2 PWM pulses are 180° out-of-phase.
In this configuration, the ISEN3/FB2 pin (pin 9) serves
the FB2 function.
For 1-phase configuration, tie the PWM3 and ISEN2 pins
to 5V. In this configuration, only Phase-1 is active. The
ISEN3/FB2, ISEN2, and ISEN1 pins are not used because
there is no need for either current balancing or FB2
function.
R
fset
fset
(
kΩ
)
fset
resistor between the COMP and the VW pins
=
(
value. 8kΩ R
Period μs
3
(
™ modulator can naturally achieve
) 0.29
–
17
fset
)
×
gives approximately
2.65
ISL62883, ISL62883B
3
™ Modulator
3
™
(EQ. 17)
Modes of Operation
Table 2 shows the ISL62883 operational modes,
programmed by the logic status of the PSI# and the
DPRSLPVR pins. In 3-phase configuration, the ISL62883
enters 2-phase CCM for (PSI# = 0 and DPRSLPVR = 0)
by dropping PWM3 and operating phases 1 and 2 180°
out-of-phase. It also reduces the overcurrent and the
way-overcurrent protection levels to 2/3 of the initial
values. The ISL62883 enters 1-phase DE mode when
DPRSLPVR = 1. It drops phases 2 and 3, and reduces
the overcurrent and the way-overcurrent protection
levels to 1/3 of the initial values.
In 2-phase configuration, the ISL62883 enters 1-phase
CCM for (PSI# = 0 and DPRSLPVR = 0). It drops phase 2
and reduces the overcurrent and the way-overcurrent
protection levels to 1/2 of the initial values. The
ISL62883 enters 1-phase DE mode when DPRSLPVR = 1
by dropping phase 2.
In 1-phase configuration, the ISL62883 does not change
the operational mode when the PSI# signal changes
status. It enters 1-phase DE mode when DPRSLPVR = 1.
Dynamic Operation
The ISL62883 responds to VID changes by slewing to the
new voltage at 5mV/µs slew rate. As the output
approaches the VID command voltage, the dv/dt
moderates to prevent overshoot. Geyserville-III
transitions commands one LSB VID step (12.5mV) every
2.5µs, controlling the effective dv/dt at 5mv/µs. The
ISL62883 is capable of 5mV/µs slew rate.
3-phase
Configuration
2-phase
Configuration
1-phase
Configuration
CONFIGURATION
TABLE 2. ISL62883 MODES OF OPERATION
PSI#
0
0
1
1
0
0
1
1
0
0
1
1
DPRSLPVR
0
1
0
1
0
1
0
1
0
1
0
1
2-phase CCM
1-phase DE
3-phase CCM
1-phase DE
1-phase CCM
1-phase DE
2-phase CCM
1-phase DE
1-phase CCM
1-phase DE
1-phase CCM
1-phase DE
OPERATIONAL
MODE
FN6891.3