ISL6313B Datasheet, PDF (17/33 Pages) Intersil Corporation – Two-Phase Buck PWM Controller with Integrated MOSFET Drivers for Intel VR11 and AMD Applications

ISL6313B
TABLE 4. AMD 6-BIT VOLTAGE IDENTIFICATION CODES
VID5 VID4 VID3 VID2 VID1 VID0 VDAC
0
1
1
1
0
0
0.8500
0
1
1
1
0
1
0.8250
0
1
1
1
1
0
0.8000
0
1
1
1
1
1
0.7750
1
0
0
0
0
0
0.7625
1
0
0
0
0
1
0.7500
1
0
0
0
1
0
0.7375
1
0
0
0
1
1
0.7250
1
0
0
1
0
0
0.7125
1
0
0
1
0
1
0.7000
1
0
0
1
1
0
0.6875
1
0
0
1
1
1
0.6750
1
0
1
0
0
0
0.6625
1
0
1
0
0
1
0.6500
1
0
1
0
1
0
0.6375
1
0
1
0
1
1
0.6250
1
0
1
1
0
0
0.6125
1
0
1
1
0
1
0.6000
1
0
1
1
1
0
0.5875
1
0
1
1
1
1
0.5750
1
1
0
0
0
0
0.5625
1
1
0
0
0
1
0.5500
1
1
0
0
1
0
0.5375
1
1
0
0
1
1
0.5250
1
1
0
1
0
0
0.5125
1
1
0
1
0
1
0.5000
1
1
0
1
1
0
0.4875
1
1
0
1
1
1
0.4750
1
1
1
0
0
0
0.4625
1
1
1
0
0
1
0.4500
1
1
1
0
1
0
0.4375
1
1
1
0
1
1
0.4250
1
1
1
1
0
0
0.4125
1
1
1
1
0
1
0.4000
1
1
1
1
1
0
0.3875
1
1
1
1
1
1
0.3750
Voltage Regulation
The integrating compensation network shown in Figure 7
insures that the steady-state error in the output voltage is
limited only to the error in the reference voltage (output of
the DAC) and offset errors in the OFS current source,
remote-sense and error amplifiers. Intersil specifies the
guaranteed tolerance of the ISL6313B to include the
combined tolerances of each of these elements.
The output of the error amplifier, V_COMP, is used by the
modulator to generate the PWM signals. The PWM signals
control the timing of the Internal MOSFET drivers and
regulate the converter output so that the voltage at FB is
equal to the voltage at REF. This will regulate the output
voltage to be equal to Equation 8. The internal and external
circuitry that controls voltage regulation is illustrated in
Figure 7.
V_OUT = V_REF – V_OFS – V_DROOP
(EQ. 8)
The ISL6313B incorporates differential remote-sense
amplification in the feedback path. The differential sensing
removes the voltage error encountered when measuring the
output voltage relative to the controller ground reference
point resulting in a more accurate means of sensing output
voltage.
EXTERNAL CIRCUIT
COMP
ISL6313B INTERNAL CIRCUIT
C_C
R_C
FB
REF
C_REF
R_FB
+
(V_DROOP + V_OFS)
-
+
V_OUT
-
VSEN
RGND
I_AVG
I_OFS
-
V_COMP
+ _ERROR
AMPLIFIER
2k
∑
+
+
VID
DAC
FIGURE 7. OUTPUT VOLTAGE AND LOAD-LINE
REGULATION WITH OFFSET ADJUSTMENT
Load-Line (Droop) Regulation
Some microprocessor manufacturers require a precisely-
controlled output resistance. This dependence of output
voltage on load current is often termed “droop” or “load line”
regulation. By adding a well controlled output impedance,
the output voltage can effectively be level shifted in a
direction which works to achieve the load-line regulation
required by these manufacturers.
17
FN6809.0
November 6, 2008