IP1837TRPBF International Rectifier, IP1837TRPBF Datasheet - Page 17

• 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

An overcurrent detection trips the OCP comparator,
latches OCP signal and cycles the soft start function in
hiccup mode. The hiccup is performed by shorting the
soft‐start capacitor to ground and counting the number of
switching cycles. The Soft Start pin is held low until 4096
cycles have been completed.
Following this, the OCP signal resets and the converter
recovers. After every soft start cycle, the converter stays in
this mode until the overload or short circuit is removed.
For the iP1837, the Sync FET is turned OFF on the falling
edge of a PWMSet or Clock signal that has a duration of
25% of the switching period.
For operation at the maximum duty cycle, the OCP circuit
samples current for 40 ns, starting 40 ns after the low drive
signal for the Sync FET > 70% of PVcc.
T
For operating duty cycles less than the maximum duty
cycle of 75%, the OCP circuit still samples current for
typically 40ns, but starts sampling 40 ns after the rising
edge of PWMSet .
ABLE
2:
O
VERCURRENT SETTING VS
17
I
otrip
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
(A)
March 3, 2011 | V1.24
External Rocset (kohm)
.
E
XTERNAL
Open
4.02
4.42
4.87
6.04
7.68
8.66
11.5
13.7
16.2
26.1
35.7
54.9
113
5.4
6.8
10
20
R
OCSET
Highly Integrated 35A Single‐input Voltage,
Synchronous Buck Regulator
Thus, for low duty cycle operation, the inductor current is
sensed close to the valley. This allows a longer delay after
the falling edge of the switch node, than the corresponding
delay for an over‐current sensing scheme which samples
the current at the peak of the inductor current. This longer
delay serves to filter out any noise on the switch node and
hence on the OCSet pin, making this method more
immune to false tripping.
THERMAL SHUTDOWN
Temperature sensing is provided inside iP1837.
The trip threshold is typically set to 145
trip threshold is exceeded, thermal shutdown turns
off both MOSFETs and discharges the soft start capacitor.
Automatic restart is initiated when the sensed
temperature drops within the operating range. There
is a 20
TRIMMABLE RISING EDGE DEADBAND
The iP1837 has a rising edge deadband that is post‐
package trimmable. It is typically trimmed to 5ns‐10ns
which is an optimal range to minimize switching transition
loss and at the same time, prevent cross conduction.
REMOTE VOLTAGE SENSING
True differential remote sensing in the feedback loop is
critical to high current applications where the output
voltage across the load may differ from the output voltage
measured locally across an output capacitor at the output
inductor, and to applications that require die voltage
sensing.
The Vosp and Vosm pins of the iP1837 form the inputs to
a remote sense differential amplifier with high speed, low
input offset (post‐package trimmed to +/‐3mV) and low
input bias current which ensure accurate voltage sensing
and fast transient response in such applications.
It should be noted, however, that the output Voso of the
difference amplifier also forms the input toa power good
comparator and overvoltage comparator, both referenced
to an upper threshold of 0.7V as discussed in the next
section. Hence, in applications where Vo > 0.6V, it is
necessary to use a resistive divider network after Vo to
attenuate the sensed output voltage signal between the
remote Vo and the remote ground to 0.6V, which is then
applied between Vosp and Vosm.
o
C hysteresis in the thermal shutdown threshold.
o
C. When the
iP1837
97600