isl6306 Intersil Corporation, isl6306 Datasheet - Page 16

• Manufacturer Part Number: isl6306
• Description: 4-phase Pwm Controller With 8-bit Dac Code Capable Of Precision Rds On Or Dcr Differential Current Sensing
• Manufacturer: Intersil Corporation

NOTE: *Channels 3 and 4 are optional for 2 or 3 phases design.
Channel current balance is essential in achieving the
thermal advantage of multiphase operation. With good
current balance, the power loss is equally dissipated over
multiple devices and a greater area.
Voltage Regulation
The compensation network shown in Figure 8 assures 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 ISL6306 to include the combined tolerances of each of
these elements.
The output of the error amplifier, V
sawtooth waveform to generate the PWM signals. The PWM
signals control the timing of the Intersil MOSFET drivers and
regulate the converter output to the specified reference
voltage. The internal and external circuitry, which control
voltage regulation, are illustrated in Figure 8.
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
FIGURE 7. CHANNEL-1 PWM FUNCTION AND CURRENT-
V
COMP
FILTER
BALANCE ADJUSTMENT
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
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I
ER
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f(jω)
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Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
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For information regarding Intersil Corporation and its products, see www.intersil.com
I
AVG
SAWTOOTH SIGNAL
16
÷ N
COMP
+
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, is compared to the
Σ
PWM1
I
I
I
4
3
2
*
*
ISL6306
The ISL6306 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
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 VID7
through VID0. The DAC decodes the 8 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.
FIGURE 8. OUTPUT VOLTAGE AND LOAD-LINE
R
FB
EXTERNAL CIRCUIT
V
V
OUT
OUT
+
-
V
DROOP
C
R
REF
-
+
C
REGULATION WITH OFFSET ADJUSTMENT
R
C
REF
C
IDROOP
RGND
COMP
VDIFF
VSEN
DAC
REF
FB
ISL6306 INTERNAL CIRCUIT
I
AVG
DIFFERENTIAL
REMOTE-SENSE
AMPLIFIER
ERROR AMPLIFIER
+
-
+
-
December 8, 2006
V
COMP
DIFF
FN9226.1
, is