ISL6316 Intersil Corporation, ISL6316 Datasheet - Page 15

• Manufacturer Part Number: ISL6316
• Description: Enhanced 4-Phase PWM Controller
• Manufacturer: Intersil Corporation

NOTE: *Channels 3 and 4 are optional.
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 ISL6316 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 is illustrated in Figure 8.
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FIGURE 7. CHANNEL-1 PWM FUNCTION AND CURRENT-
V
COMP
FILTER
BALANCE ADJUSTMENT
+
I
ER
-
+
f(jω)
I
1
-
I
AVG
SAWTOOTH SIGNAL
15
÷ N
COMP
+
-
, is compared to the
Σ
PWM1
I
I
I
4
3
2
*
*
ISL6316
The ISL6316 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
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 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
DIFF
FB
, is connected to the inverting input
ISL6316 INTERNAL CIRCUIT
I
AVG
DIFFERENTIAL
REMOTE-SENSE
AMPLIFIER
ERROR AMPLIFIER
+
-
+
-
V
August 31, 2005
COMP
FN9227.0