ISL6217 Intersil Corporation, ISL6217 Datasheet - Page 13

• Manufacturer Part Number: ISL6217
• Description: Precision Multi-Phase Buck PWM Controller
• Manufacturer: Intersil Corporation

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current feedback is desired, a discrete Precision Current
Sense Resistor, R POWER , may be inserted between the
SOURCE of each channel’s lower MOSFET and ground.
The small R ISEN resistor, as described above, is then
replaced with a standard 1% resistor and connected from
the ISEN pin of the ISL6217 controller to the SOURCE of
the lower MOSFET.
Battery Feed-Forward Compensation - VBAT
The ISL6217 incorporates Battery Voltage Feed-Forward
Compensation, as shown in Figure 9. This compensation
provides a constant Pulse Width Modulator Gain
independent of battery voltage. An understanding of this
gain is required for proper loop compensation. The Battery
Voltage is connected directly to the ISL6217 by way of the
VBAT pin, and the gain of the system ramp modulator is a
constant 6.0.
FIGURE 9.
V
DROOP
_
+
R
C
DROOP
SIMPLIFIED BLOCK DIAGRAM OF THE ISL6217 VOLTAGE AND CURRENT CONTROL LOOPS FOR A TWO CHANNEL
REGULATOR. THE 38 LEAD TSSOP PACKAGE IS SHOWN.
SOFT
SOFT
EA+
ISL6217
FB
I
DROOP
IMVP-IV_
IMVP-IV+_
REFERENCE
AMPLIFIER
ERROR
-
+
13
R
2
C
2
C
1
BALANCE
BALANCE
+
+
COMP
R1
-
-
Σ
Σ
Σ
Σ
-
-
I
AVERAGE
V
V
ERROR2
ERROR1
+
+
AVERAGING
+
-
+
-
CURRENT
COMPARATOR
ISL6217
COMPARATOR
CURRENT
CURRENT
SENSING
SENSING
CIRCUIT
CIRCUIT
PWM 1
PWM 2
Fault Protection
The ISL6217 protects the CPU from damaging stress
levels. The overcurrent trip point is integral in preventing
output shorts of varying degrees from causing current
spikes that would damage a CPU. The output overvoltage
and Undervoltage detection features insure a safe window
of operation for the CPU.
Output Voltage Monitoring
VSEN is connected to the local CORE output voltage and
is used for PGOOD, Under-Voltage and overvoltage
sensing only. (Refer to “Block Diagram”) .
The voltage on VSEN is compared with two voltage levels
which indicate an overvoltage or undervoltage condition of
the output. Violating either of these conditions results in the
PGOOD pin toggling low to indicate a problem with the
output voltage.
C
DCPL
ISEN1
ISEN2
UG2
UG1
LG2
LG1
+
R
R
V
ISEN2
ISEN1
rdson
-
Q
Q
2
4
V
V
IN
IN
Q
Q
-
V
+
1
3
rdson
PHASE
PHASE
L
I
01
L1
L
I
L2
02
C
V
CORE
OUT
R
LOAD