ISL6564 Datasheet, PDF (15/27 Pages) Intersil Corporation – Multi-Phase PWM Controller with Linear 6-bit DAC Capable of Precision rDS(ON) or DCR Differential Current Sensing

ISL6564
EXTERNAL CIRCUIT
R_C C_{C COMP}
R_REF
C_REF
DAC
REF
FB
+
IDROOP
R_{FB VDROOP}
-
VDIFF
ISL6564 INTERNAL CIRCUIT
I_AVG
+
-
V_COMP
ERROR AMPLIFIER
V_OUT+
VSEN
+
V_OUT-
RGND
-
DIFFERENTIAL
REMOTE-SENSE
AMPLIFIER
FIGURE 8. OUTPUT VOLTAGE AND LOAD-LINE
REGULATION WITH OFFSET ADJUSTMENT
The ISL6564 incorporates an internal differential remote-
sense amplifier in the feedback path. The amplifier removes
the voltage error encountered when measuring the output
voltage relative to the local controller ground reference point
resulting in a more accurate means of sensing output
voltage. Connect the microprocessor sense pins to the non-
inverting input, VSEN, and inverting input, RGND, of the
remote-sense amplifier. The remote-sense output, V_DIFF, is
connected to the inverting input of the error amplifier through
an external resistor.
A digital to analog converter (DAC) generates a reference
voltage based on the state of logic signals at pins VID4
through VID12.5. The DAC decodes the a 6-bit logic signal
(VID) into one of the discrete voltages shown in Table 1.
Each VID input offers a 45µA pull-up to an internal 2.5V
source for use with open-drain outputs. The pull-up current
diminishes to zero above the logic threshold to protect
voltage-sensitive output devices. External pull-up resistors
can augment the pull-up current sources if case leakage into
the driving device is greater than 45µA.
Load-Line 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.
TABLE 1. VOLTAGE IDENTIFICATION (VID) CODES
VID5 VID4 VID3 VID2 VID1 VID0
VDAC
400 200 100 50
25
12.5
mV mV mV mv
mV
mV
1
1
1
1
1
1
OFF
1
1
1
1
1
0
1.3000V
1
1
1
1
0
1
1.2875V
1
1
1
1
0
0
1.2750V
1
1
1
0
1
1
1.2625V
1
1
1
0
1
0
1.2500V
1
1
1
0
0
1
1.2375V
1
1
1
0
0
0
1.2250V
1
1
0
1
1
1
1.2125V
1
1
0
1
1
0
1.2000V
1
1
0
1
0
1
1.1875V
1
1
0
1
0
0
1.1750V
1
1
0
0
1
1
1.1625V
1
1
0
0
1
0
1.1500V
1
1
0
0
0
1
1.1375V
1
1
0
0
0
0
1.1250v
1
0
1
1
1
1
1.1125V
1
0
1
1
1
0
1.1000V
1
0
1
1
0
1
1.0875V
1
0
1
1
0
0
1.0750V
1
0
1
0
1
1
1.0625V
1
0
1
0
1
0
1.0500V
1
0
1
0
0
1
1.0375V
1
0
1
0
0
0
1.0250V
1
0
0
1
1
1
1.0125V
1
0
0
1
1
0
1.0000V
1
0
0
1
0
1
0.9875V
1
0
0
1
0
0
0.9750V
1
0
0
0
1
1
0.9625V
1
0
0
0
1
0
0.9500V
1
0
0
0
0
1
0.9375V
1
0
0
0
0
0
0.9250V
0
1
1
1
1
1
0.9125V
0
1
1
1
1
0
0.9000V
0
1
1
1
0
1
0.8875V
0
1
1
1
0
0
0.8750V
15
FN9156.2
December 27, 2004