ISL6565ACBZ Intersil, ISL6565ACBZ Datasheet - Page 16

• Manufacturer Part Number: ISL6565ACBZ
• Description: IC CTRLR PWM MULTIPHASE 28-SOIC
• Manufacturer: Intersil

Specifications of ISL6565ACBZ

• Pwm Type: Voltage Mode
• Number Of Outputs: 1
• Frequency - Max: 1.5MHz
• Duty Cycle: 66.7%
• Voltage - Supply: 4.75 V ~ 5.25 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: 0°C ~ 105°C
• Package / Case: 28-SOIC (7.5mm Width)
• Frequency-max: 1.5MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The ISL6565A, ISL6565B checks the VID inputs six times
every switching cycle. If the VID code is found to have
changed, the controller waits half of a complete cycle before
executing a 12.5mV change. If during the half-cycle wait
period, the difference between the DAC level and the new
VID code changes sign, no change is made. If the VID code
is more than 1 bit higher or lower than the DAC (not
recommended), the controller will execute 12.5mV changes
six times per cycle until VID and DAC are equal. It is
important to carefully control the rate of VID stepping in 1-bit
increments.
In order to ensure the smooth transition of output voltage
during VID change, a VID step change smoothing network is
required for an ISL6565A, ISL6565B based voltage
regulator. This network is composed of a 1kΩ internal
resistor between the output of DAC and the capacitor C
between the REF pin and ground. The selection of C
based on the time duration for 1 bit VID change and the
allowable delay time.
Assuming the microprocessor controls the VID change at 1
bit every T
given by Equation 15.
As an example, for a VID step change rate of 5µs per bit, the
value of C
Temperature Compensation
MOSFET r
changes in value due to temperature. Since output voltage
positioning is derived from the channel current sensed
across these two elements, any variation in resistance
results in a corresponding error in the output voltage.
The temperature coefficient, α, of the r
parameter that determines how much the resistance varies
with temperature. As temperature increases above ambient,
the average sensed current, I
the temperature coefficient and temperature rise as shown in
Equation 16.
With this resulting error, I
sum of two parts, the average sensed current at ambient
temperature and the resulting error current, I
temperature rise.
In order to compensate for this error current, the ISL6565A,
ISL6565B includes a temperature compensation circuit that
injects a current, I
C
I
I
AVG
ERR T ( )
REF
=
=
I
=
0.004X T
AVG T
REF
VID
DS(ON)
I
AVG T
(
, the relationship between C
is 22nF based on Equation 15.
AMBIENT
(
VID
AMBIENT
TCOMP
and inductor DCR are both susceptible to
)
⋅
, into the FB pin. This current is
AVG
[
)
1
⋅
+
α
16
AVG
α T T
can now be described as the
⋅
(
(
T T
, changes in proportion to
–
–
AMBIENT
AMBIENT
DS(ON)
REF
ERR
)
)
or DCR is the
]
and T
, due to the
ISL6565A, ISL6565B
(EQ. 16)
(EQ. 17)
VID
REF
(EQ. 15)
REF
is
is
,
created by pushing the average sense current through a
selectable external resistor, R
As shown in Figure 10, the voltage drop developed across
R
K
This gain creates the temperature compensation current,
I
Select R
entire range of operating temperature. The resulting droop
current accurately represents the load current; achieving a
linear, temperature-independant load line.
Initialization
Prior to initialization, proper conditions must exist on the
enable inputs and VCC. When the conditions are met, the
controller begins soft-start. Once the output voltage is within
the proper window of operation, the controller asserts
PGOOD.
Enable and Disable
While in shutdown mode, the PWM outputs are held in a
high-impedance state to assure the drivers remain off. The
following input conditions must be met before the ISL6565A,
ISL6565B is released from shutdown mode.
I
TCOMP
TCOMP
1. The bias voltage applied at VCC must reach the internal
TC
FIGURE 10. TEMPERATURE COMPENSATION CIRCUITRY
TCOMP
power-on reset (POR) rising threshold. Once this
threshold is reached, proper operation of all aspects of
the ISL6565A, ISL6565B is guaranteed. Hysteresis
between the rising and falling thresholds assure that once
enabled, the ISL6565A, ISL6565B will not inadvertently
turn off unless the bias voltage drops substantially (see
Electrical Specifications).
, which is determined by the internal IC temperature.
V
R
, that is injected into the FB pin.
DROOP
TCOMP
TCOMP
=
is then sensed and multiplied by a known gain,
I
DROOP
+
K
-
VDIFF
TC
TCOMP
⋅
R
(
such that I
T 25
FB
FB
–
ISL6565A, ISL6565B
) I
⋅
AVG
TCOMP
K
TCOMP
⋅
TC
R
TCOMP
equals I
I
AVG
.
I
I
TCOMP
AVG
ERR
December 1, 2005
over the
(EQ. 18)
FN9135.4