IP1837TRPBF International Rectifier, IP1837TRPBF Datasheet - Page 20

• 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

DESIGN PROCEDURE
APPLICATION INFORMATION
Design Example
The following example is a typical application for iP1837.
The application circuit is shown on page 1.
ENABLING THE IP1837
As explained earlier, the precise threshold of the Enable
lends itself well to implementation of a UVLO for the
Bus Voltage.
For a typical Enable threshold of V
For a V
choice.
PROGRAMMING THE FREQUENCY
For F
s
V
V
I
ΔV
ΔV
F
V
= 600 kHz, select R
R
o
s
in
o
= 35A
in
in
= 1.8V
= 600kHz
2
= 12V (13.2V max)
o
o
(min)
(min)
(transient) ≤ ±90mV for ΔIo = 10.5A @ 2.5A/µs
(ripple) ≤ ±13.5mV (±0.75%)

R
= 10.2V, R
*
20
1
V
R
in(
1
R

min
iP1837
March 3, 2011 | V1.24
2
V
R
Enable
EN
)
2
1

= 49.9K and R

V
t
= 36.5 kΩ, using Table 1.
V
EN
EN

1.2
EN
= 1.2 V
2
= 7.5K is a good
Vin
R
R
(6)
(7)
1
2
Highly Integrated 35A Single‐input Voltage,
Synchronous Buck Regulator
OUTPUT VOLTAGE PROGRAMMING
Output voltage is programmed by the reference voltage
and external voltage divider. If the remote sense feature is
used, the divider is connected to the Vosp and Vosm pins.
If only local sensing is used for feedback, with the remote
sense amplifier used only in the over‐voltage protection,
circuit, the resistive divider should be connected to the
Fb pin.
For this design, with high output current requirements, we
choose to use the true differential remote sense feature.
The Fb pin is the inverting input of the error amplifier,
which is internally referenced to 0.6V. This references the
output of the remote sense amplifier to 0.6V also. In order
to satisfy this condition, the voltage between the Vosp and
Vosm pins of the error amplifier should be 0.6V when the
output is at its desired value. The output voltage is defined
by using the following equation:
when an external resistor divider is connected to the
output as shown in Figure 16.
Equation (8) can be rewritten as:
R
Figure 16: Typical application of the iP1837
V
top
o
for programming the output voltage


V
ref
R
iP1837
bot






1
Vosp





V
R
R
o
V

bot
top
ref
V
ref








Vout
iP1837
R
R
top
bot
(9)
(8)
97600