ISL62881_14 Datasheet, PDF (15/35 Pages) Intersil Corporation – Single-Phase PWM Regulator for IMVP-6.5 Mobile CPUs and GPUs

ISL62881, ISL62881B
VID6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
VID5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
TABLE 1. VID TABLE (Continued)
VID4
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
VID3
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
VID2
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
VID1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
VID0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
V_O
(V)
0.5375
0.5250
0.5125
0.5000
0.4875
0.4750
0.4625
0.4500
0.4375
0.4250
0.4125
0.4000
0.3875
0.3750
0.3625
0.3500
0.3375
0.3250
0.3125
0.3000
0.2875
0.2750
0.2625
0.2500
0.2375
0.2250
0.2125
0.2000
0.1875
0.1750
0.1625
0.1500
0.1375
0.1250
0.1125
0.1000
0.0875
0.0750
0.0625
0.0500
0.0375
0.0250
VID6
1
1
1
1
1
1
1
1
1
VID5
1
1
1
1
1
1
1
1
1
TABLE 1. VID TABLE (Continued)
VID4
1
1
1
1
1
1
1
1
1
VID3
0
1
1
1
1
1
1
1
1
VID2
1
0
0
0
0
1
1
1
1
VID1
1
0
0
1
1
0
0
1
1
VID0
1
0
1
0
1
0
1
0
1
V_O
(V)
0.0125
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
RDROOP
FB
VDROOP
IDROOP
VCCSENSE
VR LOCAL VO
“CATCH” RESISTOR
COMP
E/A
Σ
DAC
VDAC
X1
INTERNAL TO IC
VIDS
RTN
VSS
VID<0:6>
VSSSENSE
“CATCH”
RESISTOR
FIGURE 12. DIFFERENTIAL SENSING AND LOAD LINE
IMPLEMENTATION
As the load current increases from zero, the output voltage will
droop from the VID table value by an amount proportional to the
load current to achieve the load line. The ISL62881 can sense
the inductor current through the intrinsic DC Resistance (DCR)
resistance of the inductors as shown in Figure 1 or through
resistors in series with the inductors as shown in Figure 2. In both
methods, capacitor C_n voltage represents the inductor total
currents. A droop amplifier converts C_n voltage into an internal
current source with the gain set by resistor R_i. The current source
is used for load line implementation, current monitor and
overcurrent protection.
Figure 12 shows the load line implementation. The ISL62881
drives a current source I_droop out of the FB pin, described by
Equation 1.
I_droop
=
2_----x_----V_---C----n-
R_i
(EQ. 1)
When using inductor DCR current sensing, a single NTC element
is used to compensate the positive temperature coefficient of the
copper winding thus sustaining the load line accuracy with
reduced cost.
I_droop flows through resistor R_droop and creates a voltage drop,
as shown in Equation 2.
V_droop = R_droop × I_droop
(EQ. 2)
15
FN6924.3
June 16, 2011