iru3137 International Rectifier Corp., iru3137 Datasheet - Page 3

• Manufacturer Part Number: iru3137
• Description: 8-pin Synchronous Pwm Controller
• Manufacturer: International Rectifier Corp.

PARAMETER
Error Amp
Fb Voltage Input Bias Current
Fb Voltage Input Bias Current
Transconductance
Oscillator
Frequency
Ramp-Amplitude Voltage
Output Drivers
Rise Time
Fall Time
Dead Band Time
Max Duty Cycle
Min Duty Cycle
Note 1: Guaranteed by design but not tested in production.
PIN DESCRIPTIONS
PIN#
Rev. 1.0
06/22/04
1
2
3
4
5
6
7
8
PIN SYMBOL
SS / SD
Comp
HDrv
LDrv
Vcc
Gnd
Fb
Vc
This pin is connected directly to the output of the switching regulator via resistor divider to
provide feedback to the Error amplifier.
This pin provides biasing for the internal blocks of the IC as well as power for the low side
driver. A minimum of 1 F, high frequency capacitor must be connected from this pin to
ground to provide peak drive current capability.
Output driver for the synchronous power MOSFET.
This pin serves as the ground pin and must be connected directly to the ground plane. A
high frequency capacitor (0.1 to 1 F) must be connected from VCC and Vc pins to this
pin for noise free operation.
Output driver for the high side power MOSFET. This pin should not go negative (below
ground), this may cause problem for the gate drive circuit. It can happen when the inductor
current goes negative (Source/Sink), soft-start at no load and for the fast load transient
from full load to no load. To prevent negative voltage at gate drive, a low forward voltage
drop diode might be connected between this pin and ground.
This pin is connected to a voltage that must be at least 4V higher than the bus voltage of
the switcher (assuming 5V threshold MOSFET) and powers the high side output driver. A
minimum of 1 F, high frequency capacitor must be connected from this pin to ground to
provide peak drive current capability.
Compensation pin of the error amplifier. An external resistor and capacitor network is
typically connected from this pin to ground to provide loop compensation.
This pin provides soft-start for the switching regulator. An internal current source charges
an external capacitor that is connected from this pin to ground which ramps up the output
of the switching regulator, preventing it from overshooting as well as limiting the input
current. The converter can be shutdown by pulling this pin below 2.8V.
PIN DESCRIPTION
SYM
V
Freq
T
T
GM
T
I
I
RAMP
Tr
FB1
FB2
OFF
T
ON
DB
f
SS=3V, Fb=1V
SS=0V, Fb=1V
Note 1
C
C
Fb=0.7V, Freq=200KHz
Fb=1.5V
L
L
=3000pF (10% to 90%)
=3000pF (90% to 10%)
TEST CONDITION
www.irf.com
MIN
600
180
85
TYP
1.25
850
100
0.1
50
35
35
90
MAX
1100
240
70
70
IRU3137
0
UNITS
KHz
mho
ns
ns
ns
%
%
V
A
A
3