IR3513ZMTRPBF International Rectifier, IR3513ZMTRPBF Datasheet - Page 14

• Manufacturer Part Number: IR3513ZMTRPBF
• Description: IC CTRL XPHASE3 POL 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3513ZMTRPBF

• Applications: Processor
• Current - Supply: 3mA
• Voltage - Supply: 8 V ~ 16 V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: *
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Body Braking
In a conventional synchronous buck converter, the minimum time required to reduce the current in the inductor in
response to a load step decrease is;
The slew rate of the inductor current can be significantly increased by turning off the synchronous rectifier in
response to a load step decrease. The switch node voltage is then forced to decrease until conduction of the
synchronous rectifier’s body diode occurs. This increases the voltage across the inductor from Vout to Vout +
V
decrease is now;
Since the voltage drop in the body diode is often higher than the output voltage, the inductor current slew rate can
be increased by 2X or more. This patent pending technique is referred to as “body braking” and is accomplished
through the “body braking comparator”. If the error amplifier’s output voltage drops below the VREF voltage or a
programmable voltage, this comparator turns off the low side gate driver.
Lossless Average Inductor Current Sensing
Inductor current can be sensed by connecting a series resistor and a capacitor network in parallel with the inductor
and measuring the voltage across the capacitor, as shown in Figure 6. The equation of the sensing network is,
Usually the resistor Rcs and capacitor Ccs are chosen so that the time constant of Rcs and Ccs equals the time
constant of the inductor which is the inductance L over the inductor DCR (R
voltage across Ccs is proportional to the current through L, and the sense circuit can be treated as if only a sense
resistor with the value of R
inductor DC current, but affects the AC component of the inductor current.
BODYDIODE
Page 14
. The minimum time required to reduce the current in the inductor in response to a load transient
TM
L
was used. The mismatch of the time constants does not affect the measurement of
REPLACEMENT PRODUCT – IR3513ZMTRPBF
v
NOT RECOMMENDED FOR NEW DESIGNS
C
Figure 5 - PWM Operating Waveforms
(
s
)
=
v
L
T
T
(
SLEW
SLEW
s
)
1
+
=
=
sR
L
L
V
1
CS
O
( *
( *
C
+
I
I
CS
V
MAX
MAX
BODYDIODE
V
=
O
−
−
i
L
I
I
(
MIN
MIN
s
)
1
)
)
+
R
sR
L
+
CS
sL
C
CS
L
). If the two time constants match, the
May 11, 2008
IR3513