ISL6316IRZ-T Intersil, ISL6316IRZ-T Datasheet - Page 14

• Manufacturer Part Number: ISL6316IRZ-T
• Description: IC CTRLR PWM 4PHASE ENH 40-QFN
• Manufacturer: Intersil

Specifications of ISL6316IRZ-T

• Pwm Type: Voltage Mode
• Number Of Outputs: 1
• Frequency - Max: 275kHz
• 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: -40°C ~ 85°C
• Package / Case: 40-VFQFN, 40-VFQFPN
• Frequency-max: 275kHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

With the internal low-offset current amplifier, the capacitor
voltage V
Therefore the current out of ISEN+ pin, I
to the inductor current.
Equation 5 shows that the ratio of the channel current to the
sensed current I
resistor and the DCR of the inductor.
RESISTIVE SENSING
For accurate current sense, a dedicated current-sense
resistor R
as the current sense element (see Figure 5). This technique is
more accurate, but reduces overall converter efficiency due to
the additional power loss on the current sense element
R
Equation 6 shows the ratio of the channel current to the
sensed current I
I
I
SEN
SEN
SENSE
ISL6316 INTERNAL CIRCUIT
=
=
SAMPLE
HOLD
I
I
.
L
L
FIGURE 4. DCR SENSING CONFIGURATION
C
SENSE
&
I
n
I
⋅
⋅
SEN
is replicated across the sense resistor R
----------------- -
R
R
-----------------------
DCR
R
ISL6605
ISEN
SENSE
ISEN
=
SEN
SEN
in series with each output inductor can serve
PWM(n)
I
L
.
----------------- -
R
is driven by the value of the sense
DCR
ISEN
+
-
V
IN
14
ISEN-(n)
ISEN+(n)
INDUCTOR
R
L
I
L
s ( )
V
SEN
L
V
DCR
C
-
C
(s)
, is proportional
-
R
(PTC)
ISEN(n)
C
ISEN
V
OUT
OUT
(EQ. 5)
(EQ. 6)
.
ISL6316
MOSFET r
The controller can also sense the channel load current by
sampling the voltage across the lower MOSFET r
Figure 6). The amplifier is ground-reference by connecting the
ISEN- pin to the source of the lower MOSFET. ISEN+ pin is
connected to the PHASE node through the current sense
resistor R
voltage drop across the r
is conducting. The resulting current out of the ISEN+ pin is
proportional to the channel current I
Equation 7 shows the ratio of the channel current to the
sensed current I
Both inductor DCR and MOSFET r
as the temperature increases. Therefore the sensed current
will increase as the temperature of the current sense element
increases. In order to compensate the temperature effect on
the sensed current signal, a Positive Temperature Coefficient
(PTC) resistor can be selected for the sense resistor R
I
SEN
FIGURE 6. MOSFET r
FIGURE 5. SENSE RESISTOR IN SERIES WITH INDUCTORS
ISL6316 INTERNAL CIRCUIT
SAMPLE
HOLD
=
ISL6316 INTERNAL CIRCUIT
&
I
n
I
I
L
SEN
ISEN
SAMPLE
r
----------------------
I
DS(ON)
HOLD
SEN
DS ON
R
I
&
ISEN
n
=
(
. The voltage across R
SEN
=
I L
)
I
r
------------------------- -
+
L
-
SENSING
DS ON
R
.
R SENSE
------------------------- -
ISEN
R
(
ISEN
DS(ON)
DS(ON)
+
)
-
ISEN-(n)
ISEN+(n)
CURRENT-SENSING CIRCUIT
EXTERNAL CIRCUIT
R
ISEN-(n)
ISEN+(n)
(PTC)
of the lower MOSFET while it
L
ISEN
DS(ON)
L.
ISEN
R
I
SENSE
L
V
is equivalent to the
value will increase
IN
I L x
+
-
R
ISEN(n)
C
N-CHANNEL
MOSFETs
December 12, 2006
r
V
DS ON
OUT
DS(ON)
OUT
I
L
(
ISEN
FN9227.1
)
(EQ. 7)
(see
,