IP1837TRPBF International Rectifier, IP1837TRPBF Datasheet - Page 16

• Manufacturer Part Number: IP1837TRPBF
• Description: IC DC-DC REG SYNC BUCK LGA
• Manufacturer: International Rectifier
• Series: iPOWIR™r
• Type: Step-Down (Buck), PWM - Voltage Moder

Specifications of IP1837TRPBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.6 V ~ 12 V
• Current - Output: 35A
• Frequency - Switching: 250kHz ~ 1.5MHz
• Voltage - Input: 1.5 V ~ 16 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: *
• Package / Case: *
• Package: LGA - 7.7 x 7.7
• Circuit: Single Output
• Iout (a): 35
• Switch Freq (khz): 250 - 1500
• Input Range (v): 1.5 - 16
• Output Range (v): 0.6 - 0.75*Vin
• Internal Bias Ldo: Yes
• Ocp Otp Uvlo Pre-bias Soft Start And: Remote Sense + Body Tracking + Temp Comp OCP
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATING FREQUENCY
The switching frequency can be programmed between
250kHz – 1500kHz by connecting an external resistor from
R
versus R
T
SHUTDOWN
The iP1837 can be shutdown by pulling the Enable pin
below its 1 V threshold. This will tri‐state both, the high
side driver as well as the low side driver.
TEMPERATURE‐COMPENSATED
OVER‐CURRENT PROTECTION
The over current protection is performed by sensing
current through the R
method enhances the converter’s efficiency and reduces
cost by eliminating a current sense resistor. As shown in
Figure 11, an external resistor (R
between OCSet pin and the switch node (SW) which sets
the current limit set point.
ABLE
T
Figure 10: Theoretical operation waveforms during soft‐start
pin to Gnd. Table 1 tabulates the oscillator frequency
1:
S
T
.
WITCHING
16
Vss
Vout
Fsw (kHz)
POR
1000
1500
250
300
400
450
500
600
800
0.2V
F
March 3, 2011 | V1.24
t1
REQUENCY VS
DS(on)
0.8V
t2
of low side MOSFET. This
t3
R
.
T
E
OCSet
(kohm)
XTERNAL
88.7
73.2
54.9
48.7
44.2
36.5
27.4
22.1
14
) is connected
R
ESISTOR
Highly Integrated 35A Single‐input Voltage,
(R
T
)
Synchronous Buck Regulator
An internal current source sources current (I
the OCSet pin. The internal current source develops a
voltage across ROCSet. When the low side MOSFET is
turned on, the inductor current flows through Q2 and
results in a voltage at OCSet which is given by:
An over current is detected if the OCSet pin goes below
ground. Hence, at the current limit threshold, V
Then, for a current limit setting I
follows:
It should be noted that the iP1837 uses a temperature
compensated overcurrent protection scheme, i.e., I
varies with temperature with the same temperature
coeffecient as R
and is independent of temperature.
The value of Rocset calculated above is realized as a
parallel combination of an internal 2.7K resistor and an
external resistor connected between the Rocset and SW
pins. Table 2 shows the selection of the external Rocset
resistor for various values of the trip load current I
Vcc = 3.3V.
Control
Hiccup
V
OCSet
Figure 11: Connection of over‐current sensing resistor
R
OCSet

(

I
OCSet
R
DS(on)
DS

(
on
, so that I
I
R
+
-
OCSet
)
OCSet
*
I
IntV
)
Ltrip

Ltrip
CC
(
Q1
Q2
R
Ltrip
depends only on Rocset
DS
I
OCSet
,
(on
R
OCSet
PGnd
)

Vin
I
iP1837
is calculated as
L
)
OCSet
(3)
OCset
) out of
R
otrip
97600
=0.
OCSet
OCSet
SW
OCSet
(2)
at