ISL6217 Datasheet, PDF (13/19 Pages) Intersil Corporation – Precision Multi-Phase Buck PWM Precision Multi-Phase Buck PWM Positioning IMVP-IV™ and IMVP-IV+

ISL6217
current feedback is desired, a discrete Precision Current
Sense Resistor, RPOWER, may be inserted between the
SOURCE of each channel’s lower MOSFET and ground.
The small RISEN 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.
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.
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.
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.
EA+
_
V_{DROOP RDROOP}
+
SOFT
C_SOFT
R1
C₂
FB R₂ C₁ ^COMP
C_DCPL
V_IN
ERROR
AMPLIFIER
-
+
I_DROOP
IMVP-IV_
IMVP-IV+_
REFERENCE
BALANCE
+ ^{Σ V}ERROR1 ⁺
-
-
PWM 1
CIRCUIT
COMPARATOR
+
Σ
-
CURRENT
SENSING
I_{AVERAGE CURRENT}
AVERAGING
-
Σ⁺
CURRENT
SENSING
ISL6217
+ ^- VERROR2
Σ
BALANCE
+
PWM 2
-
CIRCUIT
COMPARATOR
UG1
Q₁ L01
LG1
ISEN1
Q₂
R_ISEN1
I_L1
PHASE
ISEN2
UG2
R_ISEN2
+V_rdson- _VIN
PHASE
Q³
L ₀₂
LG2
-
V_rdson ^IL2
Q_{4 +}
V_CORE
C_OUT R_LOAD
FIGURE 9. SIMPLIFIED BLOCK DIAGRAM OF THE ISL6217 VOLTAGE AND CURRENT CONTROL LOOPS FOR A TWO CHANNEL
REGULATOR. THE 38 LEAD TSSOP PACKAGE IS SHOWN.
13